开窗函数--Postgres

博客翻译自https://mode.com/resources/sql-tutorial/sql-window-functions

• 开窗函数

    从这儿开始吗？这篇是使用SQL进行数据分析教程的一部分，查看教程开始。这片文章使用的数据来自于华商顿特区的首都共享单车项目。这个项目的网站上会发布详细的骑行历史数据。数据是在2014年2月份下载的，但是这些数据仅是收集的2012年第一季度的数据。每一行代表一次骑行。大部分的字段是见文知意的，除了  rider_type  ：“Registered”代表共享单车项目的月会员，“Casual“代表骑行者购买了3天的会员。 start_dt  和  end_dt  经过清洗从原始格式转成SQL日期格式--他们以时间戳的格式储存在这张表中。

• 开窗函数介绍 

    PostgreSQL的文件很好的解释了开窗函数的定义：

        开窗函数横跨表的行集进行计算，这些行和当前行存在某种关联。这种计算可以和聚合函数的计算进行对比。但是，不像聚合函数，开窗函数不会把许多行聚合成一行输出，而是每一行         都会获得一个结果。背后的原理是，开窗函数不止可以获取查询的结果的当前行，而是整个行集。

实际应用中最常见的例子就是求合计：

SELECT duration,
       SUM（duration) OVER(ORDER BY start_dt) AS running_total
FROM bike_trip

---

 

start_dt	duration	running_total
20120101 00:04	475	475
20120101 00:10	1145	2782
20120101 00:10	1162	2782
20120101 00:15	485	3738
20120101 00:15	471	3738
20120101 00:17	358	4096
20120101 00:18	1754	5850
20120101 00:22	259	6109
20120101 00:24	516	6625
20120101 00:25	913	7538
20120101 00:29	1097	8635
20120101 00:30	490	9125
20120101 00:32	1045	11205
20120101 00:32	1035	11205
20120101 00:33	1060	14063
20120101 00:33	1039	14063
20120101 00:33	443	14063
20120101 00:33	316	14063
20120101 00:34	506	14569

 

上面的查询没有用 GROUP BY 而创建了一个聚合行 running_total .让我们分解上面查询语句的语法看看它是如何运行的。

• 开窗函数基础语法

    上面聚合函数的第一部分 SUM(duration) ，看起来跟一般聚合函数没什么区别。增加 over 标明他是一个开窗函数。你可以将上面的聚合函数这样理解“按照 start_dt 的顺序，从整个行集的首行开始到尾行对 duration 进行 sum() 运算。
如果你想将窗口范围从整个结果数据集收窄到数据集内的独立的组，你可以使用 PARTITION BY 去实现：

SELECT start_station,
       duration,
       SUM（duration) OVER(PARTITION  BY start_station ORDER BY start_dt) 
       AS running_total
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

start_station	start_dt	duration	running_total
10th & Monroe St NE	20120101 13:01	933	933
10th & Monroe St NE	20120101 14:26	1032	1965
10th & Monroe St NE	20120101 16:41	1159	3124
10th & Monroe St NE	20120101 16:55	1138	4262
10th & Monroe St NE	20120101 21:14	670	4932
10th & Monroe St NE	20120102 12:19	1597	6529
10th & Monroe St NE	20120102 18:07	865	7394
10th & Monroe St NE	20120103 08:17	1517	8911
10th & Monroe St NE	20120103 08:26	1287	10198
10th & Monroe St NE	20120103 09:13	641	10839
10th & Monroe St NE	20120103 14:05	627	11466
10th & Monroe St NE	20120103 14:15	858	12324
10th & Monroe St NE	20120103 16:01	1225	13549
10th & Monroe St NE	20120104 08:38	1355	14904
10th & Monroe St NE	20120104 08:43	633	15537
10th & Monroe St NE	20120104 08:54	1393	16930
10th & Monroe St NE	20120104 15:49	5158	22088
10th & Monroe St NE	20120104 17:35	1266	23354
10th & Monroe St NE	20120105 01:14	1437	24791
10th & Monroe St NE	20120105 08:33	925	25716
10th & Monroe St NE	20120105 08:37	1379	27095
10th & Monroe St NE	20120105 08:52	1175	28270
10th & Monroe St NE	20120105 09:56	695	28965
10th & Monroe St NE	20120105 14:03	117	29082
10th & Monroe St NE	20120105 14:05	573	29655
10th & Monroe St NE	20120105 17:14	1099	30754
10th & Monroe St NE	20120106 08:22	1478	32232
10th & Monroe St NE	20120106 08:31	853	33085
10th & Monroe St NE	20120106 08:46	1230	34315
10th & Monroe St NE	20120106 08:58	898	35213
10th & Monroe St NE	20120106 09:12	768	35981
10th & Monroe St NE	20120106 11:06	1495	37476
10th & Monroe St NE	20120106 16:46	1226	38702
10th & Monroe St NE	20120106 17:34	1681	40383
10th & Monroe St NE	20120106 17:55	660	41043
10th & Monroe St NE	20120107 09:59	974	42017
10th & Monroe St NE	20120107 11:58	725	42742
10th & Monroe St NE	20120107 14:06	1111	43853
10th & Monroe St NE	20120107 14:08	1203	45056
10th & Monroe St NE	20120107 14:42	1573	46629
10th & Monroe St NE	20120107 14:58	328	46957
10th & Monroe St NE	20120107 15:08	4673	51630
10th & Monroe St NE	20120107 16:30	1625	58165
10th & Monroe St NE	20120107 16:30	1650	58165
10th & Monroe St NE	20120107 16:30	1630	58165
10th & Monroe St NE	20120107 16:30	1630	58165
10th & Monroe St NE	20120107 16:35	979	59144
10th & Monroe St NE	20120107 16:37	927	60071
10th & Monroe St NE	20120107 16:44	795	61964
10th & Monroe St NE	20120107 16:44	1098	61964
10th & Monroe St NE	20120107 18:55	1997	63961
10th & Monroe St NE	20120107 22:12	800	64761
10th & U St NW	20120101 00:57	817	817
10th & U St NW	20120101 01:25	1130	1947
10th & U St NW	20120101 02:26	605	2552
10th & U St NW	20120101 03:03	1839	4391
10th & U St NW	20120101 03:08	429	4820
10th & U St NW	20120101 03:09	273	5093
10th & U St NW	20120101 03:11	603	5696
10th & U St NW	20120101 03:14	1163	6859
10th & U St NW	20120101 03:25	337	7196
10th & U St NW	20120101 03:26	706	7902
10th & U St NW	20120101 03:42	618	8520
10th & U St NW	20120101 04:26	422	8942
10th & U St NW	20120101 12:15	485	9427
10th & U St NW	20120101 12:52	663	10751
10th & U St NW	20120101 12:52	661	10751
10th & U St NW	20120101 14:08	1086	12918
10th & U St NW	20120101 14:08	1081	12918
10th & U St NW	20120101 14:12	412	13330
10th & U St NW	20120101 15:03	606	13936
10th & U St NW	20120101 15:22	755	14691
10th & U St NW	20120101 15:31	629	15320
10th & U St NW	20120101 15:32	476	15796
10th & U St NW	20120101 15:50	512	16308
10th & U St NW	20120101 18:33	477	16785
10th & U St NW	20120101 19:29	399	17184
10th & U St NW	20120101 20:30	393	17577
10th & U St NW	20120101 22:01	521	18627
10th & U St NW	20120101 22:01	529	18627
10th & U St NW	20120101 22:07	335	18962
10th & U St NW	20120102 00:06	395	19357
10th & U St NW	20120102 00:27	548	20472
10th & U St NW	20120102 00:27	567	20472
10th & U St NW	20120102 00:52	299	20771
10th & U St NW	20120102 01:35	402	21173
10th & U St NW	20120102 11:44	232	21405
10th & U St NW	20120102 11:49	371	21776
10th & U St NW	20120102 12:12	1031	22807
10th & U St NW	20120102 13:16	628	23435
10th & U St NW	20120102 13:18	318	23753
10th & U St NW	20120102 13:53	740	24493
10th & U St NW	20120102 14:06	435	24928
10th & U St NW	20120102 14:36	417	25345
10th & U St NW	20120102 15:08	729	26074
10th & U St NW	20120102 15:12	1260	27334
10th & U St NW	20120102 15:16	646	27980
10th & U St NW	20120102 15:49	746	29430
10th & U St NW	20120102 15:49	704	29430
10th & U St NW	20120102 16:19	75	29505
10th & U St NW	20120102 16:21	395	29900
10th & U St NW	20120102 16:29	2559	32965
10th & U St NW	20120102 16:29	506	32965
10th & U St NW	20120102 16:36	443	33408
10th & U St NW	20120102 16:52	664	34072
10th & U St NW	20120102 17:19	323	34395
10th & U St NW	20120102 17:32	157	34552
10th & U St NW	20120102 17:35	280	34832
10th & U St NW	20120102 18:08	646	35478
10th & U St NW	20120102 19:31	401	35879
10th & U St NW	20120102 21:08	756	36635
10th & U St NW	20120102 22:15	515	37150
10th & U St NW	20120103 00:40	184	37334
10th & U St NW	20120103 06:43	746	38080
10th & U St NW	20120103 06:52	187	38267
10th & U St NW	20120103 08:09	1035	39302
10th & U St NW	20120103 08:12	581	39883
10th & U St NW	20120103 08:15	461	40344
10th & U St NW	20120103 08:19	789	41133
10th & U St NW	20120103 08:27	757	41890
10th & U St NW	20120103 08:38	933	42823
10th & U St NW	20120103 09:14	620	43443
10th & U St NW	20120103 09:17	619	44062
10th & U St NW	20120103 09:53	858	44920
10th & U St NW	20120103 10:03	421	45341
10th & U St NW	20120103 11:33	973	47299
10th & U St NW	20120103 11:33	985	47299
10th & U St NW	20120103 12:18	387	47686
10th & U St NW	20120103 13:03	521	48207
10th & U St NW	20120103 13:34	150	48357
10th & U St NW	20120103 13:56	312	48669
10th & U St NW	20120103 15:56	732	49401
10th & U St NW	20120103 16:26	365	49766
10th & U St NW	20120103 17:15	691	50457
10th & U St NW	20120103 18:15	382	50839
10th & U St NW	20120103 18:16	389	51228
10th & U St NW	20120103 18:32	384	51612
10th & U St NW	20120103 18:48	272	51884
10th & U St NW	20120103 19:06	610	52494
10th & U St NW	20120103 19:17	640	53134
10th & U St NW	20120103 20:13	358	53492
10th & U St NW	20120104 00:08	470	53962
10th & U St NW	20120104 06:44	734	54696
10th & U St NW	20120104 07:07	831	55527
10th & U St NW	20120104 07:53	535	56062
10th & U St NW	20120104 08:10	469	56531
10th & U St NW	20120104 08:16	688	57219
10th & U St NW	20120104 08:43	639	57858
10th & U St NW	20120104 09:03	365	58223
10th & U St NW	20120104 09:04	571	58794
10th & U St NW	20120104 09:17	1131	59925
10th & U St NW	20120104 09:29	318	60243
10th & U St NW	20120104 09:38	986	61229
10th & U St NW	20120104 12:03	592	61821
10th & U St NW	20120104 15:37	403	62224
10th & U St NW	20120104 16:34	599	62823
10th & U St NW	20120104 17:22	680	63503
10th & U St NW	20120104 17:33	1181	64684
10th & U St NW	20120104 17:35	328	65012
10th & U St NW	20120104 18:36	697	66046
10th & U St NW	20120104 18:36	337	66046
10th & U St NW	20120104 18:58	499	66545
10th & U St NW	20120104 19:31	373	66918
10th & U St NW	20120104 19:56	349	67267
10th & U St NW	20120104 20:14	301	67568
10th & U St NW	20120104 20:18	336	67904
10th & U St NW	20120104 20:59	304	68208
10th & U St NW	20120104 21:42	446	68654
10th & U St NW	20120104 23:12	190	68844
10th & U St NW	20120104 23:46	401	69245
10th & U St NW	20120105 01:25	512	69757
10th & U St NW	20120105 06:41	474	70231
10th & U St NW	20120105 06:44	785	71016
10th & U St NW	20120105 06:50	215	71231
10th & U St NW	20120105 07:36	719	71950
10th & U St NW	20120105 08:01	528	72478
10th & U St NW	20120105 08:11	467	73380
10th & U St NW	20120105 08:11	435	73380
10th & U St NW	20120105 08:21	314	73694
10th & U St NW	20120105 08:24	720	74414
10th & U St NW	20120105 08:32	775	75189
10th & U St NW	20120105 08:35	277	75466
10th & U St NW	20120105 08:57	524	75990
10th & U St NW	20120105 09:11	282	76272
10th & U St NW	20120105 09:23	1075	77347
10th & U St NW	20120105 10:15	469	77816
10th & U St NW	20120105 10:20	403	78219
10th & U St NW	20120105 11:41	474	78693
10th & U St NW	20120105 14:21	427	79120
10th & U St NW	20120105 15:15	308	79428
10th & U St NW	20120105 16:45	347	79775
10th & U St NW	20120105 17:17	823	80598
10th & U St NW	20120105 17:22	616	81214
10th & U St NW	20120105 17:33	576	81790
10th & U St NW	20120105 18:07	355	82145
10th & U St NW	20120105 18:28	301	82446
10th & U St NW	20120105 18:30	998	83444
10th & U St NW	20120105 18:38	348	83792
10th & U St NW	20120105 19:02	1173	84965
10th & U St NW	20120105 19:11	1154	86119
10th & U St NW	20120105 19:16	601	86720
10th & U St NW	20120105 19:26	377	87097
10th & U St NW	20120105 19:42	215	87312
10th & U St NW	20120105 19:54	813	88923
10th & U St NW	20120105 19:54	798	88923
10th & U St NW	20120105 19:55	752	89675
10th & U St NW	20120105 21:37	1048	90723
10th & U St NW	20120106 00:46	453	91622
10th & U St NW	20120106 00:46	446	91622
10th & U St NW	20120106 06:43	341	91963
10th & U St NW	20120106 06:45	680	92643
10th & U St NW	20120106 07:39	597	93240
10th & U St NW	20120106 07:48	221	93461
10th & U St NW	20120106 08:13	463	93924
10th & U St NW	20120106 08:14	310	94234
10th & U St NW	20120106 08:24	1520	95754
10th & U St NW	20120106 08:32	415	96169
10th & U St NW	20120106 08:44	801	96970
10th & U St NW	20120106 08:46	722	97692
10th & U St NW	20120106 08:49	292	97984
10th & U St NW	20120106 08:51	380	98874
10th & U St NW	20120106 08:51	510	98874
10th & U St NW	20120106 09:05	415	99289
10th & U St NW	20120106 09:07	843	100132
10th & U St NW	20120106 09:17	691	100823
10th & U St NW	20120106 09:20	4668	105491
10th & U St NW	20120106 09:22	947	106438
10th & U St NW	20120106 09:25	578	107016
10th & U St NW	20120106 09:26	504	107520
10th & U St NW	20120106 09:55	951	108471
10th & U St NW	20120106 10:35	846	109317
10th & U St NW	20120106 11:17	379	109696
10th & U St NW	20120106 11:53	336	110032
10th & U St NW	20120106 12:01	582	110614
10th & U St NW	20120106 14:58	758	111372
10th & U St NW	20120106 15:23	423	111795
10th & U St NW	20120106 15:37	903	112698
10th & U St NW	20120106 15:42	303	113156
10th & U St NW	20120106 15:42	155	113156
10th & U St NW	20120106 16:16	3653	116809
10th & U St NW	20120106 16:17	3636	120445
10th & U St NW	20120106 16:43	491	120936
10th & U St NW	20120106 17:15	1398	122334
10th & U St NW	20120106 17:19	450	123111
10th & U St NW	20120106 17:19	327	123111
10th & U St NW	20120106 17:42	377	123488
10th & U St NW	20120106 17:48	489	123977
10th & U St NW	20120106 17:49	476	124453
10th & U St NW	20120106 17:58	510	124963
10th & U St NW	20120106 18:08	398	125361
10th & U St NW	20120106 18:16	1222	126583
10th & U St NW	20120106 18:21	761	128120
10th & U St NW	20120106 18:21	776	128120
10th & U St NW	20120106 18:30	859	128979
10th & U St NW	20120106 18:37	450	129429
10th & U St NW	20120106 18:55	156	129585
10th & U St NW	20120106 19:09	380	129965
10th & U St NW	20120106 20:01	335	130300
10th & U St NW	20120106 20:14	338	130638
10th & U St NW	20120106 20:18	587	131225
10th & U St NW	20120106 20:39	1272	132497
10th & U St NW	20120106 21:27	417	132914
10th & U St NW	20120106 21:28	254	133168
10th & U St NW	20120106 21:29	627	133795
10th & U St NW	20120106 21:42	550	134345
10th & U St NW	20120106 21:54	193	134538
10th & U St NW	20120106 21:57	237	134775
10th & U St NW	20120106 22:02	451	135702
10th & U St NW	20120106 22:02	476	135702
10th & U St NW	20120106 22:54	605	136307
10th & U St NW	20120106 23:09	429	137162
10th & U St NW	20120106 23:09	426	137162
10th & U St NW	20120106 23:10	1143	138305
10th & U St NW	20120106 23:52	878	139183
10th & U St NW	20120107 00:10	313	139496
10th & U St NW	20120107 00:45	429	140364
10th & U St NW	20120107 00:45	439	140364
10th & U St NW	20120107 01:13	177	140541
10th & U St NW	20120107 01:30	227	140993
10th & U St NW	20120107 01:30	225	140993
10th & U St NW	20120107 01:53	297	141290
10th & U St NW	20120107 01:59	170	141460
10th & U St NW	20120107 02:05	576	142036
10th & U St NW	20120107 02:14	222	142258
10th & U St NW	20120107 02:54	976	143234
10th & U St NW	20120107 04:07	827	144061
10th & U St NW	20120107 08:28	637	144698
10th & U St NW	20120107 08:33	308	145006
10th & U St NW	20120107 08:52	144	145150
10th & U St NW	20120107 09:01	574	145724
10th & U St NW	20120107 09:16	160	145884
10th & U St NW	20120107 09:31	1096	146980
10th & U St NW	20120107 11:08	308	147568
10th & U St NW	20120107 11:08	280	147568
10th & U St NW	20120107 11:18	290	147858
10th & U St NW	20120107 11:21	354	148212
10th & U St NW	20120107 11:29	733	148945
10th & U St NW	20120107 11:50	540	149485
10th & U St NW	20120107 12:06	1025	151540
10th & U St NW	20120107 12:06	1030	151540
10th & U St NW	20120107 12:13	499	152039
10th & U St NW	20120107 12:28	716	152755
10th & U St NW	20120107 12:31	1116	155036
10th & U St NW	20120107 12:31	1165	155036
10th & U St NW	20120107 13:15	328	155364
10th & U St NW	20120107 13:44	7978	171326
10th & U St NW	20120107 13:44	7984	171326
10th & U St NW	20120107 13:58	638	171964
10th & U St NW	20120107 14:08	428	172392
10th & U St NW	20120107 14:16	3536	175928
10th & U St NW	20120107 14:56	473	176401
10th & U St NW	20120107 15:21	639	177040
10th & U St NW	20120107 15:40	490	178020
10th & U St NW	20120107 15:40	490	178020
10th & U St NW	20120107 15:53	297	178317
10th & U St NW	20120107 16:08	985	179302
10th & U St NW	20120107 16:19	3280	182582
10th & U St NW	20120107 16:21	357	182939
10th & U St NW	20120107 16:52	499	184003
10th & U St NW	20120107 16:52	565	184003
10th & U St NW	20120107 17:07	571	184574
10th & U St NW	20120107 17:14	811	185385
10th & U St NW	20120107 17:34	535	186465
10th & U St NW	20120107 17:34	545	186465
10th & U St NW	20120107 17:37	874	187339
10th & U St NW	20120107 18:05	534	188771
10th & U St NW	20120107 18:05	898	188771
10th & U St NW	20120107 18:09	420	189191
10th & U St NW	20120107 18:32	133	189324
10th & U St NW	20120107 18:33	216	189540
10th & U St NW	20120107 19:12	209	189936
10th & U St NW	20120107 19:12	187	189936
10th & U St NW	20120107 19:44	679	190615
10th & U St NW	20120107 20:39	917	191532
10th & U St NW	20120107 21:25	303	191835
10th & U St NW	20120107 21:28	596	192431
10th & U St NW	20120107 21:29	561	192992
10th & U St NW	20120107 22:06	428	193420
10th & U St NW	20120107 22:32	787	194207
10th & U St NW	20120107 22:38	227	194434
10th & U St NW	20120107 22:51	523	194957
10th & U St NW	20120107 23:29	615	195572
10th & U St NW	20120107 23:43	646	196218
10th St & Constitution Ave NW	20120101 13:41	1383	2775
10th St & Constitution Ave NW	20120101 13:41	1392	2775
10th St & Constitution Ave NW	20120101 13:49	2061	4836
10th St & Constitution Ave NW	20120101 13:50	2008	6844
10th St & Constitution Ave NW	20120101 13:57	1389	8233
10th St & Constitution Ave NW	20120101 14:08	1395	9628
10th St & Constitution Ave NW	20120101 14:10	620	10248
10th St & Constitution Ave NW	20120101 14:11	1810	13885
10th St & Constitution Ave NW	20120101 14:11	1827	13885
10th St & Constitution Ave NW	20120101 15:02	415	14300
10th St & Constitution Ave NW	20120101 15:41	844	15144
10th St & Constitution Ave NW	20120101 16:19	620	15764
10th St & Constitution Ave NW	20120101 16:25	686	16450
10th St & Constitution Ave NW	20120101 16:33	1057	18540
10th St & Constitution Ave NW	20120101 16:33	1033	18540
10th St & Constitution Ave NW	20120101 16:36	784	20125
10th St & Constitution Ave NW	20120101 16:36	801	20125
10th St & Constitution Ave NW	20120101 16:40	715	20840
10th St & Constitution Ave NW	20120101 17:23	1366	22206
10th St & Constitution Ave NW	20120101 17:42	815	23981
10th St & Constitution Ave NW	20120101 17:42	960	23981
10th St & Constitution Ave NW	20120101 17:43	774	24755
10th St & Constitution Ave NW	20120101 19:01	989	26735
10th St & Constitution Ave NW	20120101 19:01	991	26735
10th St & Constitution Ave NW	20120101 19:53	1279	29315
10th St & Constitution Ave NW	20120101 19:53	1301	29315
10th St & Constitution Ave NW	20120102 10:28	349	29664
10th St & Constitution Ave NW	20120102 12:31	1356	31020
10th St & Constitution Ave NW	20120102 12:34	1236	32256
10th St & Constitution Ave NW	20120102 14:05	2212	36682
10th St & Constitution Ave NW	20120102 14:05	2214	36682
10th St & Constitution Ave NW	20120102 16:06	498	37180
10th St & Constitution Ave NW	20120102 16:10	1731	38911
10th St & Constitution Ave NW	20120102 17:04	767	39678
10th St & Constitution Ave NW	20120102 17:08	1224	40902
10th St & Constitution Ave NW	20120102 18:08	1055	41957
10th St & Constitution Ave NW	20120103 06:26	366	42323
10th St & Constitution Ave NW	20120103 07:41	219	42542
10th St & Constitution Ave NW	20120103 07:51	269	42811
10th St & Constitution Ave NW	20120103 08:14	1293	44104
10th St & Constitution Ave NW	20120103 14:23	1706	47534
10th St & Constitution Ave NW	20120103 14:23	1724	47534
10th St & Constitution Ave NW	20120103 14:53	747	48281
10th St & Constitution Ave NW	20120103 16:22	342	48623
10th St & Constitution Ave NW	20120103 16:39	677	49300
10th St & Constitution Ave NW	20120103 17:20	728	50028
10th St & Constitution Ave NW	20120103 17:38	1835	51863
10th St & Constitution Ave NW	20120103 18:00	281	52144
10th St & Constitution Ave NW	20120104 08:09	1318	53462
10th St & Constitution Ave NW	20120104 08:28	412	53874
10th St & Constitution Ave NW	20120104 11:48	435	54309
10th St & Constitution Ave NW	20120104 13:45	1111	55420
10th St & Constitution Ave NW	20120104 16:22	317	55737
10th St & Constitution Ave NW	20120104 16:26	874	56611
10th St & Constitution Ave NW	20120104 17:00	476	57087
10th St & Constitution Ave NW	20120104 18:00	282	57369
10th St & Constitution Ave NW	20120105 08:18	1167	58536
10th St & Constitution Ave NW	20120105 08:34	275	58811
10th St & Constitution Ave NW	20120105 08:45	1030	59841
10th St & Constitution Ave NW	20120105 12:19	2779	62620
10th St & Constitution Ave NW	20120105 12:35	257	62877
10th St & Constitution Ave NW	20120105 14:03	987	63864
10th St & Constitution Ave NW	20120105 15:50	508	64372
10th St & Constitution Ave NW	20120105 16:21	2108	66480
10th St & Constitution Ave NW	20120105 16:36	1311	69109
10th St & Constitution Ave NW	20120105 16:36	1318	69109
10th St & Constitution Ave NW	20120105 17:12	1032	70141
10th St & Constitution Ave NW	20120105 17:13	694	70835
10th St & Constitution Ave NW	20120105 17:14	605	71440
10th St & Constitution Ave NW	20120105 17:23	1001	72441
10th St & Constitution Ave NW	20120105 17:47	430	72871
10th St & Constitution Ave NW	20120105 18:00	239	73110
10th St & Constitution Ave NW	20120105 18:09	1301	74411
10th St & Constitution Ave NW	20120105 18:12	1171	75582
10th St & Constitution Ave NW	20120105 18:40	599	76181
10th St & Constitution Ave NW	20120105 20:29	497	76678
10th St & Constitution Ave NW	20120106 08:19	1103	77781
10th St & Constitution Ave NW	20120106 08:34	329	78110
10th St & Constitution Ave NW	20120106 09:34	400	78510
10th St & Constitution Ave NW	20120106 09:50	617	79127
10th St & Constitution Ave NW	20120106 10:47	1728	80855
10th St & Constitution Ave NW	20120106 10:48	1675	82530
10th St & Constitution Ave NW	20120106 13:10	899	83429
10th St & Constitution Ave NW	20120106 13:45	258	83687
10th St & Constitution Ave NW	20120106 13:49	1227	84914
10th St & Constitution Ave NW	20120106 14:06	440	85354
10th St & Constitution Ave NW	20120106 16:08	4201	93737
10th St & Constitution Ave NW	20120106 16:08	4182	93737
10th St & Constitution Ave NW	20120106 16:16	1279	95016
10th St & Constitution Ave NW	20120106 16:43	3529	102067
10th St & Constitution Ave NW	20120106 16:43	3522	102067
10th St & Constitution Ave NW	20120106 16:57	486	102553
10th St & Constitution Ave NW	20120106 16:58	616	103169
10th St & Constitution Ave NW	20120106 17:28	958	104127
10th St & Constitution Ave NW	20120106 17:31	1399	105526
10th St & Constitution Ave NW	20120106 17:33	322	105848
10th St & Constitution Ave NW	20120106 17:45	1460	107308
10th St & Constitution Ave NW	20120106 17:52	2991	113289
10th St & Constitution Ave NW	20120106 17:52	2990	113289
10th St & Constitution Ave NW	20120106 18:36	244	113533
10th St & Constitution Ave NW	20120106 19:58	484	114017
10th St & Constitution Ave NW	20120106 21:18	1234	116488
10th St & Constitution Ave NW	20120106 21:18	1237	116488
10th St & Constitution Ave NW	20120106 22:33	1001	117489
10th St & Constitution Ave NW	20120106 22:43	1464	118953
10th St & Constitution Ave NW	20120107 09:51	403	119762
10th St & Constitution Ave NW	20120107 09:51	406	119762
10th St & Constitution Ave NW	20120107 12:06	7388	134563
10th St & Constitution Ave NW	20120107 12:06	7413	134563
10th St & Constitution Ave NW	20120107 12:30	760	135323
10th St & Constitution Ave NW	20120107 13:07	546	135869
10th St & Constitution Ave NW	20120107 13:10	3557	142998
10th St & Constitution Ave NW	20120107 13:10	3572	142998
10th St & Constitution Ave NW	20120107 13:17	416	148296
10th St & Constitution Ave NW	20120107 13:17	407	148296
10th St & Constitution Ave NW	20120107 13:17	4475	148296
10th St & Constitution Ave NW	20120107 13:18	4446	152742
10th St & Constitution Ave NW	20120107 13:19	4384	157126
10th St & Constitution Ave NW	20120107 13:21	1770	158896
10th St & Constitution Ave NW	20120107 13:22	1718	160614
10th St & Constitution Ave NW	20120107 14:09	568	161182
10th St & Constitution Ave NW	20120107 14:10	1473	162655
10th St & Constitution Ave NW	20120107 14:59	1473	164128
10th St & Constitution Ave NW	20120107 15:00	1466	165594
10th St & Constitution Ave NW	20120107 15:07	858	166452
10th St & Constitution Ave NW	20120107 15:15	700	167866
10th St & Constitution Ave NW	20120107 15:15	714	167866
10th St & Constitution Ave NW	20120107 15:36	1245	169111
10th St & Constitution Ave NW	20120107 16:12	530	169641
10th St & Constitution Ave NW	20120107 16:17	916	170557
10th St & Constitution Ave NW	20120107 16:24	689	171246
10th St & Constitution Ave NW	20120107 16:32	1458	172704
10th St & Constitution Ave NW	20120107 16:46	468	173172
10th St & Constitution Ave NW	20120107 16:53	5353	183886
10th St & Constitution Ave NW	20120107 16:53	5361	183886
10th St & Constitution Ave NW	20120107 17:37	307	184193
10th St & Constitution Ave NW	20120107 17:41	1164	189440
10th St & Constitution Ave NW	20120107 17:41	1180	189440
10th St & Constitution Ave NW	20120107 17:41	2903	189440
10th St & Constitution Ave NW	20120107 17:42	3198	195875
10th St & Constitution Ave NW	20120107 17:42	3237	195875
10th St & Constitution Ave NW	20120107 18:11	6341	202216
10th St & Constitution Ave NW	20120107 18:12	5471	207687
10th St & Constitution Ave NW	20120107 18:13	5485	213172
10th St & Constitution Ave NW	20120107 18:14	6207	219379
10th St & Constitution Ave NW	20120107 22:43	1097	221555
10th St & Constitution Ave NW	20120107 22:43	1079	221555
10th St & Constitution Ave NW	20120107 23:03	1226	222781
10th St & Constitution Ave NW	20120107 23:04	1207	223988
11th & H St NE	20120101 14:41	505	505
11th & H St NE	20120101 14:54	539	1044
11th & H St NE	20120101 15:43	625	1669
11th & H St NE	20120101 15:44	589	2258
11th & H St NE	20120101 16:07	789	3047
11th & H St NE	20120101 19:32	1191	4238
11th & H St NE	20120101 20:46	467	4705
11th & H St NE	20120101 21:29	1230	6542
11th & H St NE	20120101 21:29	607	6542
11th & H St NE	20120102 11:16	741	7283
11th & H St NE	20120102 12:19	917	8200
11th & H St NE	20120102 12:25	725	8925
11th & H St NE	20120102 12:48	1090	11101
11th & H St NE	20120102 12:48	1086	11101
11th & H St NE	20120102 13:10	751	11852
11th & H St NE	20120102 13:11	206	12058
11th & H St NE	20120102 13:17	571	12629
11th & H St NE	20120102 14:14	545	13174
11th & H St NE	20120102 14:27	895	14069
11th & H St NE	20120102 20:11	244	14313
11th & H St NE	20120103 07:00	1039	15352
11th & H St NE	20120103 08:10	967	16319
11th & H St NE	20120103 08:11	336	16655
11th & H St NE	20120103 08:12	1357	18758
11th & H St NE	20120103 08:12	746	18758
11th & H St NE	20120103 08:28	337	19095
11th & H St NE	20120103 08:41	326	19421
11th & H St NE	20120103 08:59	555	19976
11th & H St NE	20120103 09:12	446	20422
11th & H St NE	20120103 13:04	373	20795
11th & H St NE	20120103 13:46	356	21151
11th & H St NE	20120103 14:47	352	21503
11th & H St NE	20120103 18:23	347	21850
11th & H St NE	20120103 19:48	146	21996
11th & H St NE	20120103 22:15	1801	23797
11th & H St NE	20120104 06:05	1196	24993
11th & H St NE	20120104 08:08	937	25930
11th & H St NE	20120104 08:11	304	26234
11th & H St NE	20120104 08:18	851	27085
11th & H St NE	20120104 08:54	346	27431
11th & H St NE	20120104 12:56	304	27735
11th & H St NE	20120104 17:13	407	28142
11th & H St NE	20120104 18:19	584	28726
11th & H St NE	20120104 18:25	284	29010
11th & H St NE	20120104 18:32	425	29435
11th & H St NE	20120104 18:50	527	29962
11th & H St NE	20120104 19:10	562	30524
11th & H St NE	20120104 21:33	546	31070
11th & H St NE	20120104 21:34	508	31578
11th & H St NE	20120105 06:46	919	32497
11th & H St NE	20120105 07:47	921	33418
11th & H St NE	20120105 08:11	304	33722
11th & H St NE	20120105 08:24	865	34587
11th & H St NE	20120105 08:40	360	34947
11th & H St NE	20120105 08:44	520	35467
11th & H St NE	20120105 12:10	398	35865
11th & H St NE	20120105 14:55	350	36215
11th & H St NE	20120105 15:32	408	36623
11th & H St NE	20120105 17:37	234	36857
11th & H St NE	20120105 18:34	340	37197
11th & H St NE	20120105 20:26	280	37756
11th & H St NE	20120105 20:26	279	37756
11th & H St NE	20120105 22:08	526	38282
11th & H St NE	20120105 22:25	310	38592

     

    上面的查询通过 start_station 和 start_dt 进行分组和排序。在每一个 start_station 分组里面是按照 start_dt 进行排序的，求和函数是对当前行和之前所有行的 duration 进行求和。按照这样的规则向下滚动执行，直到分组字段 start_station 的值变化了，你会注意到分组字段值变化后，聚合函数 running_total 也会重新滚动计算。那就是你用 PARTITION BY 进行分组后的效果。担心你仍被 ORDER BY 所困惑，再做一下解释，它只是用被指定的排序列排序，就像 ORDER BY 表达式所实现的效果一样，除了它将每个分区（分组）当作一个独立的部分之外没其他区别。它也可以不带ORDER BY 去执行求和操作，那么每个结果值就仅是各自 start_station 分组中所有 duration 值的和。试着不带 ORDER BY 去运行上面的查询看看：

 

SELECT start_station_num,
       duration,
       SUM（duration) OVER(PARTITION  BY
        start_station_num) 
       AS running_total
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

start_station_num	duration	running_total
31000	277	12207
31000	414	12207
31000	447	12207
31000	424	12207
31000	74	12207
31000	387	12207
31000	291	12207
31000	393	12207
31000	412	12207
31000	2661	12207
31000	399	12207
31000	398	12207
31000	520	12207
31000	348	12207
31000	3340	12207
31000	1422	12207
31001	220	39505
31001	181	39505
31001	1099	39505
31001	304	39505
31001	191	39505
31001	303	39505
31001	269	39505
31001	180	39505
31001	256	39505
31001	261	39505
31001	679	39505
31001	245	39505
31001	2876	39505
31001	2804	39505
31001	2686	39505
31001	800	39505
31001	1157	39505
31001	738	39505
31001	160	39505
31001	173	39505
31001	179	39505
31001	317	39505
31001	204	39505
31001	186	39505
31001	162	39505
31001	1168	39505
31001	501	39505
31001	1740	39505
31001	395	39505
31001	3624	39505
31001	3598	39505
31001	294	39505
31001	155	39505
31001	214	39505
31001	156	39505
31001	331	39505
31001	1103	39505
31001	188	39505
31001	992	39505
31001	294	39505
31001	138	39505
31001	1264	39505
31001	120	39505
31001	245	39505
31001	138	39505
31001	1747	39505
31001	186	39505
31001	222	39505
31001	222	39505
31001	212	39505
31001	155	39505
31001	286	39505
31001	448	39505
31001	202	39505
31001	1426	39505
31001	773	39505
31001	338	39505
31002	94	87171
31002	2540	87171
31002	661	87171
31002	676	87171
31002	1512	87171
31002	5113	87171
31002	450	87171
31002	3794	87171
31002	974	87171
31002	1367	87171
31002	462	87171
31002	104	87171
31002	1585	87171
31002	1482	87171
31002	1359	87171
31002	2050	87171
31002	578	87171
31002	213	87171
31002	41427	87171
31002	170	87171
31002	1523	87171
31002	120	87171
31002	422	87171
31002	1462	87171
31002	70	87171
31002	305	87171
31002	1202	87171
31002	1478	87171
31002	2965	87171
31002	568	87171
31002	1441	87171
31002	252	87171
31002	297	87171
31002	1373	87171
31002	150	87171
31002	86	87171
31002	71	87171
31002	197	87171
31002	1015	87171
31002	90	87171
31002	2457	87171
31002	787	87171
31002	360	87171
31002	1491	87171
31002	378	87171
31003	134	33345
31003	3563	33345
31003	1262	33345
31003	2128	33345
31003	2063	33345
31003	2008	33345
31003	337	33345
31003	2034	33345
31003	268	33345
31003	147	33345
31003	82	33345
31003	308	33345
31003	191	33345
31003	290	33345
31003	1573	33345
31003	108	33345
31003	336	33345
31003	1204	33345
31003	598	33345
31003	190	33345
31003	351	33345
31003	250	33345
31003	96	33345
31003	1540	33345
31003	108	33345
31003	179	33345
31003	2858	33345
31003	494	33345
31003	243	33345
31003	276	33345
31003	4441	33345
31003	104	33345
31003	3581	33345
31004	589	6349
31004	123	6349
31004	264	6349
31004	1216	6349
31004	116	6349
31004	214	6349
31004	146	6349
31004	164	6349
31004	204	6349
31004	151	6349
31004	226	6349
31004	172	6349
31004	127	6349
31004	263	6349
31004	145	6349
31004	400	6349

 

    ORDER BY 和 PARTITION 定义了规则，依据这个规则形成了窗口——即数据的有序子集，从首行到末行函数滚动进行计算。 

注意：你不能在同一个查询中同时使用开窗函数和标准的聚合函数。更明确来说，你不能在 GROUP BY 表达式中使用开窗函数。

 

• 通常的疑问：SUM，COUNT，AVG函数呢

    当要使用窗口函数时，你可以像正常情况下使用聚合函数那样应用同样的聚合函数——SUM,COUNT和AVG。理解这些最容易的方法就是使用更多的函数重跑上面的例子。

SELECT start_station_num,
       duration,
       SUM(duration) OVER(PARTITION  BY
        start_station_num) AS running_total
       COUNT(duration) OVER(PARTITION  BY
        start_station_num) AS running_count
       AVG(duration) OVER(PARTITION  BY
        start_station_num) AS running_avg
FROM bikestrip
WHERE start_dt < '2012-01-08'

---

 

start_station_num	duration	running_total	running_count	running_avg
31000	277	12207	16	762.9375
31000	414	12207	16	762.9375
31000	447	12207	16	762.9375
31000	424	12207	16	762.9375
31000	74	12207	16	762.9375
31000	387	12207	16	762.9375
31000	291	12207	16	762.9375
31000	393	12207	16	762.9375
31000	412	12207	16	762.9375
31000	2661	12207	16	762.9375
31000	399	12207	16	762.9375
31000	398	12207	16	762.9375
31000	520	12207	16	762.9375
31000	348	12207	16	762.9375
31000	3340	12207	16	762.9375
31000	1422	12207	16	762.9375
31001	220	39505	57	693.070175438596
31001	181	39505	57	693.070175438596
31001	1099	39505	57	693.070175438596
31001	304	39505	57	693.070175438596
31001	191	39505	57	693.070175438596
31001	303	39505	57	693.070175438596
31001	269	39505	57	693.070175438596
31001	180	39505	57	693.070175438596
31001	256	39505	57	693.070175438596
31001	261	39505	57	693.070175438596
31001	679	39505	57	693.070175438596
31001	245	39505	57	693.070175438596
31001	2876	39505	57	693.070175438596
31001	2804	39505	57	693.070175438596
31001	2686	39505	57	693.070175438596
31001	800	39505	57	693.070175438596
31001	1157	39505	57	693.070175438596
31001	738	39505	57	693.070175438596
31001	160	39505	57	693.070175438596
31001	173	39505	57	693.070175438596
31001	179	39505	57	693.070175438596
31001	317	39505	57	693.070175438596
31001	204	39505	57	693.070175438596
31001	186	39505	57	693.070175438596
31001	162	39505	57	693.070175438596
31001	1168	39505	57	693.070175438596
31001	501	39505	57	693.070175438596
31001	1740	39505	57	693.070175438596
31001	395	39505	57	693.070175438596
31001	3624	39505	57	693.070175438596
31001	3598	39505	57	693.070175438596
31001	294	39505	57	693.070175438596
31001	155	39505	57	693.070175438596
31001	214	39505	57	693.070175438596
31001	156	39505	57	693.070175438596
31001	331	39505	57	693.070175438596
31001	1103	39505	57	693.070175438596
31001	188	39505	57	693.070175438596
31001	992	39505	57	693.070175438596
31001	294	39505	57	693.070175438596
31001	138	39505	57	693.070175438596
31001	1264	39505	57	693.070175438596
31001	120	39505	57	693.070175438596
31001	245	39505	57	693.070175438596
31001	138	39505	57	693.070175438596
31001	1747	39505	57	693.070175438596
31001	186	39505	57	693.070175438596
31001	222	39505	57	693.070175438596
31001	222	39505	57	693.070175438596
31001	212	39505	57	693.070175438596
31001	155	39505	57	693.070175438596
31001	286	39505	57	693.070175438596
31001	448	39505	57	693.070175438596
31001	202	39505	57	693.070175438596
31001	1426	39505	57	693.070175438596
31001	773	39505	57	693.070175438596
31001	338	39505	57	693.070175438596
31002	94	87171	45	1937.13333333333
31002	2540	87171	45	1937.13333333333
31002	661	87171	45	1937.13333333333
31002	676	87171	45	1937.13333333333
31002	1512	87171	45	1937.13333333333
31002	5113	87171	45	1937.13333333333
31002	450	87171	45	1937.13333333333
31002	3794	87171	45	1937.13333333333
31002	974	87171	45	1937.13333333333
31002	1367	87171	45	1937.13333333333
31002	462	87171	45	1937.13333333333
31002	104	87171	45	1937.13333333333
31002	1585	87171	45	1937.13333333333
31002	1482	87171	45	1937.13333333333
31002	1359	87171	45	1937.13333333333
31002	2050	87171	45	1937.13333333333
31002	578	87171	45	1937.13333333333
31002	213	87171	45	1937.13333333333
31002	41427	87171	45	1937.13333333333
31002	170	87171	45	1937.13333333333
31002	1523	87171	45	1937.13333333333
31002	120	87171	45	1937.13333333333
31002	422	87171	45	1937.13333333333
31002	1462	87171	45	1937.13333333333
31002	70	87171	45	1937.13333333333
31002	305	87171	45	1937.13333333333
31002	1202	87171	45	1937.13333333333
31002	1478	87171	45	1937.13333333333
31002	2965	87171	45	1937.13333333333
31002	568	87171	45	1937.13333333333
31002	1441	87171	45	1937.13333333333
31002	252	87171	45	1937.13333333333
31002	297	87171	45	1937.13333333333
31002	1373	87171	45	1937.13333333333
31002	150	87171	45	1937.13333333333
31002	86	87171	45	1937.13333333333
31002	71	87171	45	1937.13333333333
31002	197	87171	45	1937.13333333333
31002	1015	87171	45	1937.13333333333
31002	90	87171	45	1937.13333333333
31002	2457	87171	45	1937.13333333333
31002	787	87171	45	1937.13333333333
31002	360	87171	45	1937.13333333333
31002	1491	87171	45	1937.13333333333
31002	378	87171	45	1937.13333333333
31003	134	33345	33	1010.45454545454
31003	3563	33345	33	1010.45454545454
31003	1262	33345	33	1010.45454545454
31003	2128	33345	33	1010.45454545454
31003	2063	33345	33	1010.45454545454
31003	2008	33345	33	1010.45454545454
31003	337	33345	33	1010.45454545454
31003	2034	33345	33	1010.45454545454
31003	268	33345	33	1010.45454545454
31003	147	33345	33	1010.45454545454
31003	82	33345	33	1010.45454545454
31003	308	33345	33	1010.45454545454
31003	191	33345	33	1010.45454545454
31003	290	33345	33	1010.45454545454
31003	1573	33345	33	1010.45454545454
31003	108	33345	33	1010.45454545454
31003	336	33345	33	1010.45454545454
31003	1204	33345	33	1010.45454545454
31003	598	33345	33	1010.45454545454
31003	190	33345	33	1010.45454545454
31003	351	33345	33	1010.45454545454
31003	250	33345	33	1010.45454545454
31003	96	33345	33	1010.45454545454
31003	1540	33345	33	1010.45454545454
31003	108	33345	33	1010.45454545454
31003	179	33345	33	1010.45454545454
31003	2858	33345	33	1010.45454545454
31003	494	33345	33	1010.45454545454
31003	243	33345	33	1010.45454545454
31003	276	33345	33	1010.45454545454
31003	4441	33345	33	1010.45454545454
31003	104	33345	33	1010.45454545454
31003	3581	33345	33	1010.45454545454
31004	589	6349	18	352.722222222222
31004	123	6349	18	352.722222222222
31004	264	6349	18	352.722222222222
31004	1216	6349	18	352.722222222222

     另一个，同样的函数加上 ORDER BY :

SELECT start_station_num,
       duration,
       SUM（duration) OVER(PARTITION  BY
        start_station_num ORDER BY start_dt) AS running_total
       COUNT（duration) OVER(PARTITION  BY
        start_station_num ORDER BY start_dt) AS running_count
       AVG（duration) OVER(PARTITION  BY
        start_station_num ORDER BY start_dt) AS running_avg
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

start_station_num	duration	running_total	running_count	running_avg
31000	74	74	1	74
31000	291	365	2	182.5
31000	520	885	3	295
31000	424	1756	5	351.2
31000	447	1756	5	351.2
31000	1422	3178	6	529.666666666666
31000	348	3526	7	503.714285714285
31000	277	3803	8	475.375
31000	3340	7143	9	793.666666666666
31000	414	7955	11	723.181818181818
31000	398	7955	11	723.181818181818
31000	412	8766	13	674.307692307692
31000	399	8766	13	674.307692307692
31000	2661	11427	14	816.214285714285
31000	393	12207	16	762.9375
31000	387	12207	16	762.9375
31001	162	162	1	162
31001	2876	3038	2	1519
31001	2804	5842	3	1947.33333333333
31001	2686	8528	4	2132
31001	3624	15750	6	2625
31001	3598	15750	6	2625
31001	1426	17176	7	2453.71428571428
31001	303	17479	8	2184.875
31001	269	17748	9	1972
31001	155	17903	10	1790.3
31001	304	18207	11	1655.18181818181
31001	245	18452	12	1537.66666666666
31001	173	18625	13	1432.6923076923
31001	220	19049	15	1269.93333333333
31001	204	19049	15	1269.93333333333
31001	395	19444	16	1215.25
31001	245	19689	17	1158.17647058823
31001	181	19870	18	1103.88888888888
31001	138	20008	19	1053.05263157894
31001	138	20146	20	1007.3
31001	214	20360	21	969.523809523809
31001	294	20654	22	938.818181818181
31001	1103	21757	23	945.95652173913
31001	501	22258	24	927.416666666666
31001	286	22544	25	901.76
31001	180	22724	26	874
31001	155	22879	27	847.37037037037
31001	294	23173	28	827.607142857142
31001	800	23973	29	826.655172413793
31001	191	24164	30	805.466666666666
31001	1740	27651	32	864.09375
31001	1747	27651	32	864.09375
31001	338	27989	33	848.151515151515
31001	1157	29146	34	857.235294117647
31001	331	29477	35	842.2
31001	188	29665	36	824.027777777777
31001	992	30657	37	828.567567567567
31001	120	30777	38	809.921052631578
31001	222	31221	40	780.525
31001	222	31221	40	780.525
31001	448	31669	41	772.414634146341
31001	156	31825	42	757.738095238095
31001	317	32142	43	747.488372093023
31001	738	32880	44	747.272727272727
31001	1264	34144	45	758.755555555555
31001	1168	35312	46	767.652173913043
31001	773	36085	47	767.765957446808
31001	186	36473	49	744.34693877551
31001	202	36473	49	744.34693877551
31001	212	36685	50	733.7
31001	186	36871	51	722.960784313725
31001	179	37050	52	712.5
31001	261	37567	54	695.685185185185
31001	256	37567	54	695.685185185185
31001	679	38246	55	695.381818181818
31001	1099	39345	56	702.589285714285
31001	160	39505	57	693.070175438596
31002	378	378	1	378
31002	305	683	2	341.5
31002	1202	43312	4	10828
31002	41427	43312	4	10828
31002	170	43482	5	8696.4
31002	213	43695	6	7282.5
31002	2050	45745	7	6535
31002	5113	50858	8	6357.25
31002	568	52004	10	5200.4
31002	578	52004	10	5200.4
31002	1015	53019	11	4819.90909090909
31002	1491	54510	12	4542.5
31002	197	54707	13	4208.23076923076
31002	1462	56169	14	4012.07142857142
31002	71	56240	15	3749.33333333333
31002	104	56344	16	3521.5
31002	1478	57822	17	3401.29411764705
31002	1585	59407	18	3300.38888888888
31002	297	59704	19	3142.31578947368
31002	1359	61063	20	3053.15
31002	86	61149	21	2911.85714285714
31002	90	61239	22	2783.5909090909
31002	150	61389	23	2669.08695652173
31002	974	62363	24	2598.45833333333
31002	422	62785	25	2511.4
31002	1441	64226	26	2470.23076923076
31002	252	64478	27	2388.07407407407
31002	70	64548	28	2305.28571428571
31002	94	64642	29	2229.03448275862
31002	120	64762	30	2158.73333333333
31002	1482	69279	33	2099.36363636363
31002	1512	69279	33	2099.36363636363
31002	1523	69279	33	2099.36363636363
31002	462	70191	35	2005.45714285714
31002	450	70191	35	2005.45714285714
31002	1373	71564	36	1987.88888888888
31002	661	72901	38	1918.44736842105
31002	676	72901	38	1918.44736842105
31002	3794	76695	39	1966.53846153846
31002	2457	81692	41	1992.48780487804
31002	2540	81692	41	1992.48780487804
31002	787	82479	42	1963.78571428571
31002	1367	83846	43	1949.90697674418
31002	2965	86811	44	1972.97727272727
31002	360	87171	45	1937.13333333333
31003	250	250	1	250
31003	3581	7394	3	2464.66666666666
31003	3563	7394	3	2464.66666666666
31003	2128	9522	4	2380.5
31003	2008	13593	6	2265.5
31003	2063	13593	6	2265.5
31003	2034	15627	7	2232.42857142857
31003	268	15895	8	1986.875
31003	1204	17099	9	1899.88888888888
31003	308	17407	10	1740.7
31003	337	17744	11	1613.0909090909
31003	96	17840	12	1486.66666666666
31003	243	18083	13	1391
31003	290	18373	14	1312.35714285714
31003	336	18709	15	1247.26666666666
31003	108	18817	16	1176.0625
31003	134	18951	17	1114.76470588235
31003	276	19227	18	1068.16666666666
31003	104	19331	19	1017.42105263157
31003	147	19478	20	973.9
31003	598	20076	21	956
31003	1262	21338	22	969.90909090909
31003	351	21689	23	943
31003	82	21771	24	907.125
31003	2858	24629	25	985.16
31003	108	24737	26	951.423076923076
31003	191	24928	27	923.259259259259
31003	179	25107	28	896.678571428571
31003	494	25601	29	882.793103448275
31003	1540	27141	30	904.7
31003	190	27331	31	881.645161290322
31003	1573	28904	32	903.25
31003	4441	33345	33	1010.45454545454
31004	225	225	1	225
31004	264	489	2	244.5
31004	1604	2093	3	697.666666666666
31004	400	2493	4	623.25
31004	204	2697	5	539.4
31004	226	2923	6	487.166666666666
31004	127	3050	7	435.714285714285
31004	116	3166	8	395.75
31004	151	3317	9	368.555555555555
31004	172	3489	10	348.9
31004	214	3703	11	336.636363636363
31004	164	3867	12	322.25
31004	1216	5083	13	391
31004	123	5206	14	371.857142857142
31004	145	5351	15	356.733333333333
31004	146	5497	16	343.5625
31004	263	5760	17	338.823529411764
31004	589	6349	18	352.722222222222

     确保你将前面两个查询输入了Mode（译者注：一个网站，可以连接数据库，如何连接请参考最后）并执行。接下来的练习题跟上面那些例子十分相似，所以不要重新写那些代码修改一下上面的就行。

• ROW_NUMBER()

    ROW_NUMBER() 函数的作用可从它的字面意思看出——显示一个给定行的行号。从1开始，按照开窗函数表达式中 ORDER BY 的规则，给行标行号。 ROW_NUMBER() 函数不要求你在括号内添加参数。

SELECT duration,
       ROW_NUMBER() OVER(ORDER BY start_dt) AS row_number
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

duration	row_number
475	1
1145	2
1162	3
485	4
471	5
358	6
1754	7
259	8
516	9
913	10
1097	11
490	12
1045	13
1035	14
1060	15
1039	16
443	17
316	18
506	19
956	20
244	21
319	22
157	23
511	24
199	25
499	26
460	27
931	28
398	29
558	30
606	31
144	32
886	33
241	34
468	35
460	36
438	37
444	38
198	39
179	40
378	41
305	42
817	43
107	44
494	45
1206	46
845	47
410	48

     使用 PARTITION BY 子句，在每个分组中将会重新从1开始计数。下面的查询中，对于每个起始站点都会从头开始计数：

 

SELECT start_station_num,
       duration,
       ROW_NUMBER() OVER(PARTITION  BY
       start_station_num ORDER BY start_dt) 
       AS row_number
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

start_station_num	duration	row_number
31000	74	1
31000	291	2
31000	520	3
31000	424	4
31000	447	5
31000	1422	6
31000	348	7
31000	277	8
31000	3340	9
31000	414	10
31000	398	11
31000	412	12
31000	399	13
31000	2661	14
31000	393	15
31000	387	16
31001	162	1
31001	2876	2
31001	2804	3
31001	2686	4
31001	3624	5
31001	3598	6
31001	1426	7
31001	303	8
31001	269	9
31001	155	10
31001	304	11
31001	245	12
31001	173	13
31001	220	14
31001	204	15
31001	395	16
31001	245	17
31001	181	18
31001	138	19
31001	138	20
31001	214	21
31001	294	22
31001	1103	23
31001	501	24
31001	286	25
31001	180	26
31001	155	27
31001	294	28
31001	800	29
31001	191	30
31001	1740	31
31001	1747	32
31001	338	33
31001	1157	34
31001	331	35
31001	188	36
31001	992	37
31001	120	38
31001	222	39
31001	222	40
31001	448	41
31001	156	42
31001	317	43
31001	738	44
31001	1264	45
31001	1168	46
31001	773	47
31001	186	48
31001	202	49
31001	212	50
31001	186	51
31001	179	52
31001	261	53
31001	256	54
31001	679	55
31001	1099	56
31001	160	57
31002	378	1
31002	305	2
31002	1202	3
31002	41427	4
31002	170	5
31002	213	6
31002	2050	7
31002	5113	8
31002	568	9
31002	578	10
31002	1015	11
31002	1491	12
31002	197	13
31002	1462	14
31002	71	15
31002	104	16
31002	1478	17
31002	1585	18
31002	297	19
31002	1359	20
31002	86	21
31002	90	22
31002	150	23
31002	974	24
31002	422	25
31002	1441	26
31002	252	27
31002	70	28
31002	94	29
31002	120	30
31002	1482	31
31002	1512	32
31002	1523	33
31002	462	34
31002	450	35
31002	1373	36
31002	661	37
31002	676	38
31002	3794	39
31002	2457	40
31002	2540	41
31002	787	42
31002	1367	43
31002	2965	44
31002	360	45
31003	250	1
31003	3581	2
31003	3563	3
31003	2128	4
31003	2008	5
31003	2063	6
31003	2034	7
31003	268	8
31003	1204	9

 

• RANK()和DENSE_RANK()

    RANK() 跟  ROW_NUMBER() 有略微的差别。举个栗子，你如果按照 start_dt 排序，在一些站点很可能有起始时间相同的骑行（译者注： start_dt 相同的行）。在这种情况下，他们会有相同的排名，但是 ROW_NUMBER() 会赋予他们不同的行号。

下面查询的结果中，你留意一下 start_station_num 310000分组中的第4 ，5行数据——他们的排名都为4，他们的下面一行结果得到了6的排名：

 

SELECT start_station_num,
       duration,
       RANK() OVER(PARTITION  BY
        start_station_num ORDER BY start_dt) 
       AS rank
FROM biketrip
WHERE start_dt < '2012-01-08'

---

 

start_station_num	duration	rank
31000	74	1
31000	291	2
31000	520	3
31000	424	4
31000	447	4
31000	1422	6
31000	348	7
31000	277	8
31000	3340	9
31000	414	10
31000	398	10
31000	412	12
31000	399	12
31000	2661	14
31000	393	15
31000	387	15
31001	162	1
31001	2876	2
31001	2804	3
31001	2686	4
31001	3624	5
31001	3598	5
31001	1426	7
31001	303	8
31001	269	9
31001	155	10
31001	304	11
31001	245	12
31001	173	13
31001	220	14
31001	204	14
31001	395	16
31001	245	17
31001	181	18
31001	138	19
31001	138	20
31001	214	21
31001	294	22
31001	1103	23
31001	501	24
31001	286	25
31001	180	26
31001	155	27
31001	294	28
31001	800	29
31001	191	30
31001	1740	31
31001	1747	31
31001	338	33
31001	1157	34
31001	331	35
31001	188	36
31001	992	37
31001	120	38
31001	222	39
31001	222	39
31001	448	41
31001	156	42
31001	317	43
31001	738	44
31001	1264	45
31001	1168	46
31001	773	47
31001	186	48
31001	202	48
31001	212	50
31001	186	51
31001	179	52
31001	261	53
31001	256	53
31001	679	55
31001	1099	56
31001	160	57
31002	378	1
31002	305	2
31002	1202	3
31002	41427	3
31002	170	5
31002	213	6
31002	2050	7
31002	5113	8
31002	568	9
31002	578	9
31002	1015	11
31002	1491	12
31002	197	13
31002	1462	14
31002	71	15
31002	104	16
31002	1478	17
31002	1585	18
31002	297	19
31002	1359	20
31002	86	21
31002	90	22
31002	150	23
31002	974	24
31002	422	25
31002	1441	26
31002	252	27
31002	70	28
31002	94	29
31002	120	30
31002	1482	31
31002	1512	31
31002	1523	31
31002	462	34
31002	450	34
31002	1373	36
31002	661	37
31002	676	37
31002	3794	39
31002	2457	40
31002	2540	40
31002	787	42
31002	1367	43
31002	2965	44
31002	360	45
31003	250	1
31003	3581	2
31003	3563	2
31003	2128	4
31003	2008	5
31003	2063	5
31003	2034	7
31003	268	8
31003	1204	9
31003	308	10
31003	337	11
31003	96	12
31003	243	13
31003	290	14
31003	336	15
31003	108	16
31003	134	17
31003	276	18
31003	104	19
31003	147	20
31003	598	21
31003	1262	22
31003	351	23
31003	82	24
31003	2858	25
31003	108	26
31003	191	27
31003	179	28
31003	494	29
31003	1540	30
31003	190	31
31003	1573	32
31003	4441	33
31004	225	1
31004	264	2
31004	1604	3
31004	400	4
31004	204	5
31004	226	6
31004	127	7
31004	116	8
31004	151	9
31004	172	10
31004	214	11
31004	164	12
31004	1216	13
31004	123	14
31004	145	15
31004	146	16
31004	263	17
31004	589	18
31005	720	1
31005	2925	2
31005	1948	3
31005	2055	4
31005	1768	5
31005	261	6
31005	474	7
31005	711	8
31005	656	9
31005	370	10
31005	404	11
31005	166	12
31005	2038	13
31005	140	14
31005	128	14
31005	1761	16
31005	1922	16
31005	3534	18
31005	3242	19
31005	445	20
31005	369	21
31006	424	1
31006	1056	2
31006	271	3
31006	289	4
31006	336	5
31006	512	6
31006	1267	7
31006	362	8
31006	1320	9
31006	549	10
31006	1269	11
31006	512	12
31006	1169	13
31006	1244	14
31006	1499	15
31006	939	16
31006	853	17
31006	959	18
31006	1489	19

    根据你的应用你可以使用 DENSE_RANK() 代替RANK()。想象一个场景，三条数据有相同的一个字段值。使用哪个函数，他们都会得到一样的排名。让我们举个例子，假设排名值为‘2’。下面是这两个函数如何给下一条数据赋值的区别：

1.  RANK() 函数会给相同的行排名为2，然后跳过3和4，所以下一个会是5.
2.  DENSE_RANK()  函数仍然会给所有相同的行排名为2，但是下一行会是3，没有排名序号会被跳过。

• NTILE

    你可以使用开窗函数识别一个给定的行落在哪个分位（四分位或者其他分割法。译者注：将结果集按顺序均匀装入给定数量的桶中，一个给定行所在的桶的序号）中。语法是 NTILE(*# of buckets*) 。这种用法中， ORDER BY  后面的排序列决定了一行所在哪个四分位置上（或者你规定的任何分法）。举个例子：

 

SELECT start_station_num,
       duration,
       NTILE(4) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS quartile,
       NTILE(5) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS quintile,
       NTILE(100) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS percentile
FROM biketrip
WHERE start_dt < '2012-01-08'
ORDER BY start_station_num,duration

---

 

start_station_num	duration	quartile	quintile	percentile
31000	74	1	1	1
31000	277	1	1	2
31000	291	1	1	3
31000	348	1	1	4
31000	387	2	2	5
31000	393	2	2	6
31000	398	2	2	7
31000	399	2	3	8
31000	412	3	3	9
31000	414	3	3	10
31000	424	3	4	11
31000	447	3	4	12
31000	520	4	4	13
31000	1422	4	5	14
31000	2661	4	5	15
31000	3340	4	5	16
31001	120	1	1	1
31001	138	1	1	2
31001	138	1	1	3
31001	155	1	1	4
31001	155	1	1	5
31001	156	1	1	6
31001	160	1	1	7
31001	162	1	1	8
31001	173	1	1	9
31001	179	1	1	10
31001	180	1	1	11
31001	181	1	1	12
31001	186	1	2	13
31001	186	1	2	14
31001	188	1	2	15
31001	191	2	2	16
31001	202	2	2	17
31001	204	2	2	18
31001	212	2	2	19
31001	214	2	2	20
31001	220	2	2	21
31001	222	2	2	22
31001	222	2	2	23
31001	245	2	2	24
31001	245	2	3	25
31001	256	2	3	26
31001	261	2	3	27
31001	269	2	3	28
31001	286	2	3	29
31001	294	3	3	30
31001	294	3	3	31
31001	303	3	3	32
31001	304	3	3	33
31001	317	3	3	34
31001	331	3	3	35
31001	338	3	4	36
31001	395	3	4	37
31001	448	3	4	38
31001	501	3	4	39
31001	679	3	4	40
31001	738	3	4	41
31001	773	3	4	42
31001	800	3	4	43
31001	992	4	4	44
31001	1099	4	4	45
31001	1103	4	4	46
31001	1157	4	5	47
31001	1168	4	5	48
31001	1264	4	5	49
31001	1426	4	5	50
31001	1740	4	5	51
31001	1747	4	5	52
31001	2686	4	5	53
31001	2804	4	5	54
31001	2876	4	5	55
31001	3598	4	5	56
31001	3624	4	5	57
31002	70	1	1	1
31002	71	1	1	2
31002	86	1	1	3
31002	90	1	1	4
31002	94	1	1	5
31002	104	1	1	6
31002	120	1	1	7
31002	150	1	1	8
31002	170	1	1	9
31002	197	1	2	10
31002	213	1	2	11
31002	252	1	2	12
31002	297	2	2	13
31002	305	2	2	14
31002	360	2	2	15
31002	378	2	2	16
31002	422	2	2	17
31002	450	2	2	18
31002	462	2	3	19
31002	568	2	3	20
31002	578	2	3	21
31002	661	2	3	22
31002	676	2	3	23
31002	787	3	3	24
31002	974	3	3	25
31002	1015	3	3	26
31002	1202	3	3	27
31002	1359	3	4	28
31002	1367	3	4	29
31002	1373	3	4	30
31002	1441	3	4	31
31002	1462	3	4	32
31002	1478	3	4	33
31002	1482	3	4	34
31002	1491	4	4	35
31002	1512	4	4	36
31002	1523	4	5	37
31002	1585	4	5	38
31002	2050	4	5	39
31002	2457	4	5	40
31002	2540	4	5	41
31002	2965	4	5	42
31002	3794	4	5	43
31002	5113	4	5	44
31002	41427	4	5	45
31003	82	1	1	1
31003	96	1	1	2
31003	104	1	1	3
31003	108	1	1	4
31003	108	1	1	5
31003	134	1	1	6
31003	147	1	1	7
31003	179	1	2	8
31003	190	1	2	9
31003	191	2	2	10
31003	243	2	2	11
31003	250	2	2	12
31003	268	2	2	13
31003	276	2	2	14
31003	290	2	3	15
31003	308	2	3	16
31003	336	2	3	17
31003	337	3	3	18
31003	351	3	3	19
31003	494	3	3	20
31003	598	3	3	21
31003	1204	3	4	22
31003	1262	3	4	23
31003	1540	3	4	24
31003	1573	3	4	25
31003	2008	4	4	26
31003	2034	4	4	27
31003	2063	4	5	28
31003	2128	4	5	29
31003	2858	4	5	30
31003	3563	4	5	31
31003	3581	4	5	32
31003	4441	4	5	33
31004	116	1	1	1
31004	123	1	1	2
31004	127	1	1	3
31004	145	1	1	4
31004	146	1	2	5
31004	151	2	2	6
31004	164	2	2	7
31004	172	2	2	8
31004	204	2	3	9
31004	214	2	3	10
31004	225	3	3	11
31004	226	3	3	12
31004	263	3	4	13
31004	264	3	4	14
31004	400	4	4	15
31004	589	4	5	16
31004	1216	4	5	17
31004	1604	4	5	18
31005	128	1	1	1
31005	140	1	1	2
31005	166	1	1	3
31005	261	1	1	4
31005	369	1	1	5
31005	370	1	2	6
31005	404	2	2	7
31005	445	2	2	8
31005	474	2	2	9
31005	656	2	3	10
31005	711	2	3	11
31005	720	3	3	12
31005	1761	3	3	13
31005	1768	3	4	14
31005	1922	3	4	15
31005	1948	3	4	16
31005	2038	4	4	17
31005	2055	4	5	18
31005	2925	4	5	19
31005	3242	4	5	20
31005	3534	4	5	21
31006	271	1	1	1
31006	289	1	1	2
31006	336	1	1	3
31006	362	1	1	4
31006	424	1	1	5
31006	426	1	1	6
31006	433	1	2	7
31006	512	2	2	8
31006	512	2	2	9
31006	549	2	2	10
31006	626	2	2	11
31006	725	2	2	12
31006	853	2	3	13
31006	939	2	3	14
31006	959	3	3	15
31006	1056	3	3	16
31006	1169	3	3	17
31006	1244	3	4	18
31006	1267	3	4	19
31006	1269	3	4	20
31006	1320	3	4	21
31006	1468	4	4	22
31006	1489	4	5	23
31006	1499	4	5	24
31006	2463	4	5	25
31006	2472	4	5	26
31006	3009	4	5	27
31007	91	1	1	1
31007	103	1	1	1
31007	104	1	1	2
31007	109	1	1	2
31007	115	1	1	3
31007	117	1	1	3
31007	120	1	1	4
31007	121	1	1	4
31007	124	1	1	5
31007	130	1	1	5
31007	133	1	1	6
31007	133	1	1	6
31007	137	1	1	7
31007	138	1	1	7
31007	139	1	1	8
31007	140	1	1	8
31007	140	1	1	9
31007	141	1	1	9
31007	145	1	1	10
31007	145	1	1	10
31007	146	1	1	11
31007	146	1	1	11
31007	146	1	1	12
31007	151	1	1	12
31007	153	1	1	13
31007	155	1	1	13
31007	158	1	1	14
31007	160	1	1	14
31007	160	1	2	15
31007	162	1	2	15
31007	162	1	2	16
31007	162	1	2	16
31007	163	1	2	17
31007	163	1	2	17
31007	164	1	2	18
31007	164	2	2	18
31007	167	2	2	19
31007	168	2	2	19
31007	169	2	2	20
31007	171	2	2	20
31007	171	2	2	21
31007	172	2	2	21
31007	172	2	2	22
31007	172	2	2	22
31007	173	2	2	23
31007	174	2	2	23
31007	175	2	2	24
31007	177	2	2	24
31007	180	2	2	25
31007	181	2	2	25
31007	182	2	2	26
31007	183	2	2	26
31007	185	2	2	27
31007	186	2	2	27
31007	189	2	2	28
31007	189	2	2	28
31007	191	2	3	29
31007	193	2	3	29
31007	193	2	3	30
31007	195	2	3	30
31007	196	2	3	31
31007	200	2	3	31
31007	202	2	3	32
31007	207	2	3	32
31007	211	2	3	33
31007	221	2	3	33
31007	226	2	3	34
31007	230	2	3	34
31007	234	2	3	35
31007	238	2	3	35
31007	241	3	3	36
31007	251	3	3	36
31007	252	3	3	37
31007	252	3	3	37
31007	256	3	3	38
31007	259	3	3	38
31007	259	3	3	39
31007	262	3	3	40
31007	262	3	3	41
31007	263	3	3	42
31007	263	3	3	43
31007	268	3	3	44
31007	270	3	3	45
31007	271	3	3	46
31007	272	3	4	47
31007	275	3	4	48
31007	282	3	4	49
31007	283	3	4	50
31007	283	3	4	51
31007	286	3	4	52
31007	288	3	4	53
31007	294	3	4	54
31007	294	3	4	55
31007	307	3	4	56
31007	308	3	4	57
31007	325	3	4	58
31007	329	3	4	59
31007	339	3	4	60
31007	339	3	4	61
31007	347	3	4	62
31007	350	3	4	63
31007	351	3	4	64
31007	352	3	4	65
31007	354	3	4	66
31007	372	4	4	67
31007	382	4	4	68
31007	388	4	4	69
31007	392	4	4	70
31007	397	4	4	71
31007	415	4	4	72
31007	447	4	4	73
31007	462	4	5	74
31007	475	4	5	75
31007	507	4	5	76
31007	508	4	5	77
31007	518	4	5	78
31007	528	4	5	79
31007	531	4	5	80
31007	531	4	5	81
31007	625	4	5	82
31007	650	4	5	83
31007	782	4	5	84
31007	821	4	5	85
31007	980	4	5	86
31007	1200	4	5	87

     观察查询的结果，你可以看到 percentile  列并不像你期望的那样去计算。如果你只有两条记录，你测试每一行所占的百分位时，你可能期望一条数据定义第一个百分位，第二条数据定义第100个百分位。当使用 NTILE 函数时，你实际看到的是一条数据在第一个百分位，另一条数据在第二个百分位。在 start_station_num 31000的分组中的结果中你可以看到这种情况—— percentile 列看起来就像数字排名。如果你向下滚动到 start_station_num 31007，你会看到它恰当的计算了每一行的百分位，因为那个 terminal 分组中有超过100条的数据。如果你在处理较小的窗口，记住这点，考虑四分或者差不多小的范围。

• LAG 和 LEAD

    比对当前行和前面或后面行的情况 上面的函数是经常用到的，尤其是你的数据是排过序的。你可以使用 LAG 和 LEAD 去生成列，列值从其他行中拉取——你所需做的就是输入你要从哪列拉取数据和你要从多少行远的位置拉取。 LAG :从前面的行中拉取， LEAD 从后面的行中拉取：

 

SELECT start_station_num,
       duration,
       LAG(duration,1) OVER(PARTITION  BY
        start_station_num ORDER BY duration) 
       AS lag,
       LEAD(duration,1) OVER(PARTITION  BY
        start_station_num ORDER BY duration) 
       AS  lead
FROM biketrip
WHERE start_dt < '2012-01-08'
ORDER BY start_station_num,duration

---

 

start_station_num	duration	lag	lead
31000	74	NULL	277
31000	277	74	291
31000	291	277	348
31000	348	291	387
31000	387	348	393
31000	393	387	398
31000	398	393	399
31000	399	398	412
31000	412	399	414
31000	414	412	424
31000	424	414	447
31000	447	424	520
31000	520	447	1422
31000	1422	520	2661
31000	2661	1422	3340
31000	3340	2661	NULL
31001	120	NULL	138
31001	138	120	138
31001	138	138	155
31001	155	138	155
31001	155	155	156
31001	156	155	160
31001	160	156	162
31001	162	160	173
31001	173	162	179
31001	179	173	180
31001	180	179	181
31001	181	180	186
31001	186	181	186
31001	186	186	188
31001	188	186	191
31001	191	188	202
31001	202	191	204
31001	204	202	212
31001	212	204	214
31001	214	212	220
31001	220	214	222
31001	222	220	222
31001	222	222	245
31001	245	222	245
31001	245	245	256
31001	256	245	261
31001	261	256	269
31001	269	261	286
31001	286	269	294
31001	294	286	294
31001	294	294	303
31001	303	294	304
31001	304	303	317
31001	317	304	331
31001	331	317	338
31001	338	331	395
31001	395	338	448
31001	448	395	501
31001	501	448	679
31001	679	501	738
31001	738	679	773
31001	773	738	800
31001	800	773	992
31001	992	800	1099
31001	1099	992	1103
31001	1103	1099	1157
31001	1157	1103	1168
31001	1168	1157	1264
31001	1264	1168	1426
31001	1426	1264	1740
31001	1740	1426	1747
31001	1747	1740	2686
31001	2686	1747	2804
31001	2804	2686	2876
31001	2876	2804	3598
31001	3598	2876	3624
31001	3624	3598	NULL
31002	70	NULL	71
31002	71	70	86
31002	86	71	90
31002	90	86	94
31002	94	90	104
31002	104	94	120
31002	120	104	150
31002	150	120	170
31002	170	150	197
31002	197	170	213
31002	213	197	252
31002	252	213	297
31002	297	252	305
31002	305	297	360
31002	360	305	378
31002	378	360	422
31002	422	378	450
31002	450	422	462
31002	462	450	568
31002	568	462	578
31002	578	568	661
31002	661	578	676
31002	676	661	787
31002	787	676	974
31002	974	787	1015
31002	1015	974	1202
31002	1202	1015	1359
31002	1359	1202	1367
31002	1367	1359	1373
31002	1373	1367	1441
31002	1441	1373	1462
31002	1462	1441	1478
31002	1478	1462	1482
31002	1482	1478	1491
31002	1491	1482	1512
31002	1512	1491	1523
31002	1523	1512	1585
31002	1585	1523	2050
31002	2050	1585	2457
31002	2457	2050	2540
31002	2540	2457	2965
31002	2965	2540	3794
31002	3794	2965	5113
31002	5113	3794	41427
31002	41427	5113	NULL
31003	82	NULL	96
31003	96	82	104
31003	104	96	108
31003	108	104	108
31003	108	108	134
31003	134	108	147
31003	147	134	179
31003	179	147	190
31003	190	179	191
31003	191	190	243
31003	243	191	250
31003	250	243	268
31003	268	250	276
31003	276	268	290
31003	290	276	308
31003	308	290	336
31003	336	308	337
31003	337	336	351
31003	351	337	494
31003	494	351	598
31003	598	494	1204
31003	1204	598	1262
31003	1262	1204	1540
31003	1540	1262	1573
31003	1573	1540	2008
31003	2008	1573	2034
31003	2034	2008	2063
31003	2063	2034	2128
31003	2128	2063	2858
31003	2858	2128	3563
31003	3563	2858	3581
31003	3581	3563	4441
31003	4441	3581	NULL
31004	116	NULL	123
31004	123	116	127
31004	127	123	145
31004	145	127	146
31004	146	145	151
31004	151	146	164
31004	164	151	172
31004	172	164	204
31004	204	172	214
31004	214	204	225
31004	225	214	226
31004	226	225	263
31004	263	226	264
31004	264	263	400
31004	400	264	589
31004	589	400	1216
31004	1216	589	1604
31004	1604	1216	NULL
31005	128	NULL	140
31005	140	128	166
31005	166	140	261
31005	261	166	369
31005	369	261	370
31005	370	369	404
31005	404	370	445
31005	445	404	474
31005	474	445	656
31005	656	474	711
31005	711	656	720
31005	720	711	1761
31005	1761	720	1768
31005	1768	1761	1922
31005	1922	1768	1948
31005	1948	1922	2038
31005	2038	1948	2055
31005	2055	2038	2925
31005	2925	2055	3242
31005	3242	2925	3534
31005	3534	3242	NULL
31006	271	NULL	289
31006	289	271	336
31006	336	289	362
31006	362	336	424
31006	424	362	426
31006	426	424	433
31006	433	426	512
31006	512	433	512
31006	512	512	549
31006	549	512	626
31006	626	549	725
31006	725	626	853
31006	853	725	939
31006	939	853	959
31006	959	939	1056
31006	1056	959	1169
31006	1169	1056	1244
31006	1244	1169	1267
31006	1267	1244	1269
31006	1269	1267	1320
31006	1320	1269	1468
31006	1468	1320	1489
31006	1489	1468	1499
31006	1499	1489	2463
31006	2463	1499	2472
31006	2472	2463	3009
31006	3009	2472	NULL
31007	91	NULL	103
31007	103	91	104
31007	104	103	109
31007	109	104	115
31007	115	109	117
31007	117	115	120
31007	120	117	121
31007	121	120	124
31007	124	121	130
31007	130	124	133
31007	133	130	133
31007	133	133	137
31007	137	133	138
31007	138	137	139
31007	139	138	140
31007	140	139	140
31007	140	140	141
31007	141	140	145
31007	145	141	145
31007	145	145	146
31007	146	145	146
31007	146	146	146
31007	146	146	151
31007	151	146	153
31007	153	151	155
31007	155	153	158
31007	158	155	160
31007	160	158	160
31007	160	160	162
31007	162	160	162
31007	162	162	162
31007	162	162	163
31007	163	162	163
31007	163	163	164
31007	164	163	164
31007	164	164	167
31007	167	164	168
31007	168	167	169
31007	169	168	171
31007	171	169	171
31007	171	171	172
31007	172	171	172
31007	172	172	172
31007	172	172	173
31007	173	172	174
31007	174	173	175
31007	175	174	177
31007	177	175	180
31007	180	177	181
31007	181	180	182
31007	182	181	183
31007	183	182	185
31007	185	183	186
31007	186	185	189
31007	189	186	189
31007	189	189	191
31007	191	189	193
31007	193	191	193
31007	193	193	195
31007	195	193	196
31007	196	195	200
31007	200	196	202
31007	202	200	207
31007	207	202	211
31007	211	207	221
31007	221	211	226
31007	226	221	230
31007	230	226	234
31007	234	230	238
31007	238	234	241
31007	241	238	251
31007	251	241	252
31007	252	251	252
31007	252	252	256
31007	256	252	259
31007	259	256	259
31007	259	259	262
31007	262	259	262
31007	262	262	263
31007	263	262	263
31007	263	263	268
31007	268	263	270
31007	270	268	271
31007	271	270	272
31007	272	271	275
31007	275	272	282
31007	282	275	283
31007	283	282	283
31007	283	283	286
31007	286	283	288
31007	288	286	294
31007	294	288	294
31007	294	294	307
31007	307	294	308
31007	308	307	325
31007	325	308	329
31007	329	325	339
31007	339	329	339
31007	339	339	347
31007	347	339	350
31007	350	347	351
31007	351	350	352
31007	352	351	354
31007	354	352	372
31007	372	354	382
31007	382	372	388
31007	388	382	392
31007	392	388	397
31007	397	392	415
31007	415	397	447
31007	447	415	462
31007	462	447	475
31007	475	462	507
31007	507	475	508
31007	508	507	518
31007	518	508	528
31007	528	518	531
31007	531	528	531
31007	531	531	625
31007	625	531	650
31007	650	625	782
31007	782	650	821
31007	821	782	980
31007	980	821	1200
31007	1200	980	1222
31007	1222	1200	1243
31007	1243	1222	1251
31007	1251	1243	1272
31007	1272	1251	1379
31007	1379	1272	1390
31007	1390	1379	1401
31007	1401	1390	1403

 如果要想要计算行间的差值，这个函数是非常有用的：

 

SELECT start_station_num,
       duration,
       duration  - LAG(duration,1)  
       OVER(PARTITION  BY start_station_num ORDER BY  
       duration) AS difference
FROM biketrip
WHERE start_dt < '2012-01-08'
ORDER BY start_station_num,duration

---

 

start_station_num	duration	difference
31000	74	NULL
31000	277	203
31000	291	14
31000	348	57
31000	387	39
31000	393	6
31000	398	5
31000	399	1
31000	412	13
31000	414	2
31000	424	10
31000	447	23
31000	520	73
31000	1422	902
31000	2661	1239
31000	3340	679
31001	120	NULL
31001	138	18
31001	138	0
31001	155	17
31001	155	0
31001	156	1
31001	160	4
31001	162	2
31001	173	11
31001	179	6
31001	180	1
31001	181	1
31001	186	5
31001	186	0
31001	188	2
31001	191	3
31001	202	11
31001	204	2
31001	212	8
31001	214	2
31001	220	6
31001	222	2
31001	222	0
31001	245	23
31001	245	0
31001	256	11
31001	261	5
31001	269	8
31001	286	17
31001	294	8
31001	294	0
31001	303	9
31001	304	1
31001	317	13
31001	331	14
31001	338	7
31001	395	57
31001	448	53
31001	501	53
31001	679	178
31001	738	59
31001	773	35
31001	800	27
31001	992	192
31001	1099	107
31001	1103	4
31001	1157	54
31001	1168	11
31001	1264	96
31001	1426	162
31001	1740	314
31001	1747	7
31001	2686	939
31001	2804	118
31001	2876	72
31001	3598	722
31001	3624	26
31002	70	NULL
31002	71	1
31002	86	15
31002	90	4
31002	94	4
31002	104	10
31002	120	16
31002	150	30
31002	170	20
31002	197	27
31002	213	16
31002	252	39
31002	297	45
31002	305	8
31002	360	55
31002	378	18
31002	422	44
31002	450	28
31002	462	12
31002	568	106
31002	578	10
31002	661	83
31002	676	15
31002	787	111
31002	974	187
31002	1015	41
31002	1202	187
31002	1359	157
31002	1367	8
31002	1373	6
31002	1441	68
31002	1462	21
31002	1478	16
31002	1482	4
31002	1491	9
31002	1512	21
31002	1523	11
31002	1585	62
31002	2050	465
31002	2457	407
31002	2540	83
31002	2965	425
31002	3794	829
31002	5113	1319
31002	41427	36314
31003	82	NULL
31003	96	14
31003	104	8
31003	108	4
31003	108	0
31003	134	26
31003	147	13
31003	179	32
31003	190	11
31003	191	1
31003	243	52
31003	250	7
31003	268	18
31003	276	8
31003	290	14
31003	308	18
31003	336	28
31003	337	1
31003	351	14
31003	494	143
31003	598	104
31003	1204	606
31003	1262	58
31003	1540	278
31003	1573	33
31003	2008	435
31003	2034	26
31003	2063	29
31003	2128	65
31003	2858	730
31003	3563	705
31003	3581	18
31003	4441	860
31004	116	NULL
31004	123	7
31004	127	4
31004	145	18
31004	146	1
31004	151	5
31004	164	13
31004	172	8
31004	204	32
31004	214	10
31004	225	11
31004	226	1
31004	263	37
31004	264	1
31004	400	136
31004	589	189
31004	1216	627
31004	1604	388
31005	128	NULL
31005	140	12
31005	166	26
31005	261	95
31005	369	108
31005	370	1
31005	404	34
31005	445	41
31005	474	29
31005	656	182
31005	711	55
31005	720	9
31005	1761	1041
31005	1768	7
31005	1922	154
31005	1948	26
31005	2038	90
31005	2055	17
31005	2925	870
31005	3242	317
31005	3534	292
31006	271	NULL
31006	289	18
31006	336	47
31006	362	26
31006	424	62
31006	426	2
31006	433	7
31006	512	79
31006	512	0
31006	549	37
31006	626	77
31006	725	99
31006	853	128
31006	939	86
31006	959	20
31006	1056	97
31006	1169	113
31006	1244	75
31006	1267	23
31006	1269	2
31006	1320	51
31006	1468	148
31006	1489	21
31006	1499	10
31006	2463	964
31006	2472	9
31006	3009	537
31007	91	NULL
31007	103	12
31007	104	1
31007	109	5
31007	115	6
31007	117	2
31007	120	3
31007	121	1
31007	124	3
31007	130	6
31007	133	3
31007	133	0
31007	137	4
31007	138	1
31007	139	1
31007	140	1
31007	140	0
31007	141	1
31007	145	4
31007	145	0
31007	146	1
31007	146	0
31007	146	0
31007	151	5
31007	153	2
31007	155	2
31007	158	3
31007	160	2
31007	160	0
31007	162	2
31007	162	0
31007	162	0
31007	163	1
31007	163	0
31007	164	1
31007	164	0
31007	167	3

第一行的差值列的值是 null ，因为没有要拉取的前一行。同样的，如果使用 LEAD 会在数据集的最后产生 null 。如果你想使结果更清晰一点，你可以将上面的查询包裹在一个外部查询中以去除 null 值： 

SELECT * FROM 
(
SELECT start_station_num,
       duration,
       duration  - LAG(duration,1)  
       OVER(PARTITION  BY start_station_num ORDER BY  
       duration) AS difference
FROM biketrip
WHERE start_dt < '2012-01-08'
ORDER BY start_station_num,duration
) T
WHERE T.difference IS NOT NULL

---

 

start_station_num	duration	difference
31000	277	203
31000	291	14
31000	348	57
31000	387	39
31000	393	6
31000	398	5
31000	399	1
31000	412	13
31000	414	2
31000	424	10
31000	447	23
31000	520	73
31000	1422	902
31000	2661	1239
31000	3340	679
31001	138	18
31001	138	0
31001	155	17
31001	155	0
31001	156	1
31001	160	4
31001	162	2
31001	173	11
31001	179	6
31001	180	1
31001	181	1
31001	186	5
31001	186	0
31001	188	2
31001	191	3
31001	202	11
31001	204	2
31001	212	8
31001	214	2
31001	220	6
31001	222	2
31001	222	0
31001	245	23
31001	245	0
31001	256	11
31001	261	5
31001	269	8
31001	286	17
31001	294	8
31001	294	0
31001	303	9
31001	304	1
31001	317	13
31001	331	14
31001	338	7
31001	395	57
31001	448	53
31001	501	53
31001	679	178
31001	738	59
31001	773	35
31001	800	27
31001	992	192
31001	1099	107
31001	1103	4
31001	1157	54
31001	1168	11
31001	1264	96
31001	1426	162
31001	1740	314
31001	1747	7
31001	2686	939
31001	2804	118
31001	2876	72
31001	3598	722
31001	3624	26
31002	71	1
31002	86	15
31002	90	4
31002	94	4
31002	104	10
31002	120	16
31002	150	30
31002	170	20
31002	197	27
31002	213	16
31002	252	39
31002	297	45
31002	305	8
31002	360	55
31002	378	18
31002	422	44
31002	450	28
31002	462	12
31002	568	106
31002	578	10
31002	661	83
31002	676	15
31002	787	111
31002	974	187
31002	1015	41
31002	1202	187
31002	1359	157
31002	1367	8
31002	1373	6
31002	1441	68
31002	1462	21
31002	1478	16
31002	1482	4
31002	1491	9
31002	1512	21
31002	1523	11
31002	1585	62
31002	2050	465
31002	2457	407
31002	2540	83
31002	2965	425
31002	3794	829
31002	5113	1319
31002	41427	36314
31003	96	14
31003	104	8
31003	108	4
31003	108	0
31003	134	26
31003	147	13
31003	179	32
31003	190	11
31003	191	1
31003	243	52
31003	250	7
31003	268	18
31003	276	8
31003	290	14
31003	308	18
31003	336	28
31003	337	1
31003	351	14
31003	494	143
31003	598	104
31003	1204	606
31003	1262	58
31003	1540	278
31003	1573	33
31003	2008	435
31003	2034	26
31003	2063	29
31003	2128	65
31003	2858	730
31003	3563	705
31003	3581	18
31003	4441	860
31004	123	7
31004	127	4
31004	145	18
31004	146	1
31004	151	5
31004	164	13
31004	172	8
31004	204	32
31004	214	10
31004	225	11
31004	226	1
31004	263	37
31004	264	1
31004	400	136
31004	589	189
31004	1216	627
31004	1604	388
31005	140	12
31005	166	26
31005	261	95
31005	369	108
31005	370	1
31005	404	34
31005	445	41
31005	474	29
31005	656	182
31005	711	55
31005	720	9
31005	1761	1041
31005	1768	7
31005	1922	154
31005	1948	26
31005	2038	90
31005	2055	17
31005	2925	870
31005	3242	317
31005	3534	292
31006	289	18
31006	336	47
31006	362	26
31006	424	62
31006	426	2
31006	433	7
31006	512	79
31006	512	0
31006	549	37
31006	626	77
31006	725	99
31006	853	128
31006	939	86
31006	959	20
31006	1056	97
31006	1169	113
31006	1244	75
31006	1267	23
31006	1269	2
31006	1320	51
31006	1468	148
31006	1489	21
31006	1499	10
31006	2463	964
31006	2472	9
31006	3009	537
31007	103	12
31007	104	1
31007	109	5
31007	115	6
31007	117	2
31007	120	3
31007	121	1
31007	124	3
31007	130	6
31007	133	3
31007	133	0
31007	137	4
31007	138	1
31007	139	1
31007	140	1
31007	140	0
31007	141	1
31007	145	4
31007	145	0
31007	146	1
31007	146	0
31007	146	0
31007	151	5
31007	153	2
31007	155	2
31007	158	3
31007	160	2
31007	160	0
31007	162	2
31007	162	0
31007	162	0
31007	163	1
31007	163	0
31007	164	1
31007	164	0
31007	167	3
31007	168	1
31007	169	1
31007	171	2
31007	171	0
31007	172	1
31007	172	0
31007	172	0
31007	173	1
31007	174	1
31007	175	1
31007	177	2
31007	180	3
31007	181	1
31007	182	1
31007	183	1
31007	185	2
31007	186	1
31007	189	3
31007	189	0
31007	191	2
31007	193	2
31007	193	0
31007	195	2
31007	196	1
31007	200	4
31007	202	2
31007	207	5
31007	211	4
31007	221	10
31007	226	5
31007	230	4
31007	234	4
31007	238	4
31007	241	3
31007	251	10
31007	252	1
31007	252	0
31007	256	4
31007	259	3
31007	259	0
31007	262	3
31007	262	0
31007	263	1
31007	263	0
31007	268	5
31007	270	2
31007	271	1
31007	272	1
31007	275	3
31007	282	7
31007	283	1
31007	283	0
31007	286	3
31007	288	2
31007	294	6
31007	294	0
31007	307	13
31007	308	1
31007	325	17
31007	329	4
31007	339	10
31007	339	0
31007	347	8
31007	350	3
31007	351	1
31007	352	1
31007	354	2
31007	372	18
31007	382	10
31007	388	6
31007	392	4
31007	397	5
31007	415	18
31007	447	32
31007	462	15
31007	475	13
31007	507	32
31007	508	1
31007	518	10
31007	528	10
31007	531	3
31007	531	0
31007	625	94
31007	650	25
31007	782	132
31007	821	39
31007	980	159
31007	1200	220
31007	1222	22
31007	1243	21
31007	1251	8
31007	1272	21
31007	1379	107
31007	1390	11
31007	1401	11
31007	1403	2
31007	1506	103
31007	1518	12
31007	1617	99
31007	1693	76
31007	2405	712
31008	169	17
31008	170	1
31008	176	6
31008	179	3
31008	187	8
31008	188	1
31008	194	6
31008	234	40
31008	235	1
31008	243	8
31008	244	1
31008	258	14
31008	269	11
31008	273	4
31008	275	2
31008	287	12
31008	293	6
31008	304	11
31008	323	19
31008	329	6
31008	362	33
31008	377	15
31008	415	38
31008	427	12
31008	438	11

• 定义窗口别名

    如果你打算在同一查询中用相同的窗口写多个开窗函数，你可以为窗口创建一个别名。拿上面 NTILE 的例子示范：

SELECT start_station_num,
       duration,
       NTILE(4) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS quartile,
       NTILE(5) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS quintile,
       NTILE(100) OVER(PARTITION  BY
       start_station_num ORDER BY duration) 
       AS percentile
FROM biketrip
WHERE start_dt < '2012-01-08'
ORDER BY start_station_num,duration

这个查询可以重写成这样：

SELECT start_station_num,
       duration,
       NTILE(4) OVER ntile_window       AS quartile,
       NTILE(5) OVER ntile_window       AS quintile,
       NTILE(100) OVER ntile_window     AS percentile
FROM biketrip
WHERE start_dt < '2012-01-08'
WINDOW ntile_window AS 
        (PARTITON BY start_station_num ORDER BY duration)
ORDER BY start_station_num,duration

 

 如果包含 WINDOW 子句，应该总是在 WHERE 子句后面。

 

• 高级窗口技术

你可以在 Postgres documentation 查看在Postgres数据库(Mode所用的语法规则）中开窗函数的完整的清单。如果你在连接数据库（译者注：可以使用Mode连接你的数据库）上使用开窗函数，你应该看一下针对你的系统的语法教程。