表内容的操作
1、增
insert into 表 (列名,列名...) values (值,值,值...)
insert into 表 (列名,列名...) values (值,值,值...),(值,值,值...)
insert into 表 (列名,列名...) select 列名,列名... from 表
2、删
#删除表
drop table 表名 #先清空表
#清表数据
delete from 表名
delete from 表名 where 条件1 and 条件2
3、改
update 表 set 列名 ＝ '值' where 条件
4、查
select * from 表
select * from 表 where 条件
select 列名1,列名2,列名3 as 新列名 from 表 where 条件 #as 更改列名3显示的列名
5、其他(条件、通配符、分页、排序、连表、组合、分组)
A、按条件
mysql> select * from a;
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
| 5 | wuhua | 12 | 1 |
| 6 | laohu | 33 | 4 |
| 7 | houyi | 23 | 2 |
| 8 | zhengzheng | 33 | 5 |
+-----+------------+------+----------+
8 rows in set (0.00 sec)~~~A.a~~~ select * from 表 where 条件1 and 条件2 and 条件3;
mysql> select * from a where age = 23 and part_nid = 2;
+-----+-------+------+----------+
| nid | name | age | part_nid |
+-----+-------+------+----------+
| 7 | houyi | 23 | 2 |
+-----+-------+------+----------+
1 row in set (0.00 sec)~~~A.b~~~ select * from 表 where nid between 2 and 5; #nid等于2到5范围内
mysql> select * from a where nid between 2 and 5;
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 2 | wanwu | 18 | 2 |
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
| 5 | wuhua | 12 | 1 |
+-----+----------+------+----------+
4 rows in set (0.00 sec)~~~A.c~~~ select * from 表 where nid in (1,3,4) #nid 等于1或3或4
mysql> select * from a where nid in (1,3,4);
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
+-----+----------+------+----------+
3 rows in set (0.00 sec)~~~A.e~~~ select * from 表 where id not in (11,22,33)#id 不等于1或3或4
mysql> select * from a where nid not in (1,3,4);
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 2 | wanwu | 18 | 2 |
| 5 | wuhua | 12 | 1 |
| 6 | laohu | 33 | 4 |
| 7 | houyi | 23 | 2 |
| 8 | zhengzheng | 33 | 5 |
+-----+------------+------+----------+
5 rows in set (0.00 sec)~~~A.f~~~ select * from 表 where nid in (select nid from 表) #nid 是否包含在nid里
#b表nid只有1-6
mysql> select * from a where nid in (select nid from b);
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
| 5 | wuhua | 12 | 1 |
| 6 | laohu | 33 | 4 |
+-----+----------+------+----------+
6 rows in set (0.00 sec)
B、通配符
~~~B.a~~~ select * from 表 where 列名 like 'zh%' - zh开头的所有（多个字符串）
mysql> select * from a where name like 'zhang%';
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 4 | zhangfei | 22 | 5 |
+-----+----------+------+----------+
2 rows in set (0.00 sec)
~~~B.b~~~ select * from 表 where 列名 like 'zhangsa_' - zhengsa开头的所有（一个字符）
mysql> select * from a where name like 'zhangsa_';
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 1 | zhangsan | 18 | 2 |
+-----+----------+------+----------+
1 row in set (0.00 sec)
~~~B.c~~~ select * from 表 where 列名 like '%ng%' - 列里面所有包含ng
mysql> select * from a where name like '%ng%';
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 4 | zhangfei | 22 | 5 |
| 8 | zhengzheng | 33 | 5 |
+-----+------------+------+----------+
3 rows in set (0.00 sec)
C、分页
~~~C.a~~~ select * from 表 limit 2; - 前2行
mysql> select * from a limit 2;
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
+-----+----------+------+----------+
2 rows in set (0.00 sec)
~~~C.b~~~ select * from 表 limit 2,5; - 从第2行开始的5行
select * from 表 limit 5 offset 2 - 从第2行开始的5行 #2种写法一样 尽量用这种
mysql> select * from a limit 5 offset 2;
+-----+----------+------+----------+
| nid | name | age | part_nid |
+-----+----------+------+----------+
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
| 5 | wuhua | 12 | 1 |
| 6 | laohu | 33 | 4 |
| 7 | houyi | 23 | 2 |
+-----+----------+------+----------+
5 rows in set (0.01 sec)
D、排序
~~~D.a~~~ select * from 表 order by 列 asc - 根据 “列” 从小到大排列
mysql> select * from a order by part_nid;
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 5 | wuhua | 12 | 1 |
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 7 | houyi | 23 | 2 |
| 3 | lisi | 19 | 3 |
| 6 | laohu | 33 | 4 |
| 4 | zhangfei | 22 | 5 |
| 8 | zhengzheng | 33 | 5 |
+-----+------------+------+----------+
8 rows in set (0.00 sec)
~~~D.b~~~ select * from 表 order by 列 desc - 根据 “列” 从大到小排列
mysql> select * from a order by part_nid desc;
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 4 | zhangfei | 22 | 5 |
| 8 | zhengzheng | 33 | 5 |
| 6 | laohu | 33 | 4 |
| 3 | lisi | 19 | 3 |
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 7 | houyi | 23 | 2 |
| 5 | wuhua | 12 | 1 |
+-----+------------+------+----------+
8 rows in set (0.00 sec)
~~~D.c~~~ select * from 表 order by 列1 desc,列2 asc - 根据 “列1” 从大到小排列，如果相同则按列2从小到大排序
mysql> select * from a order by age desc,age asc;
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 6 | laohu | 33 | 4 |
| 8 | zhengzheng | 33 | 5 |
| 7 | houyi | 23 | 2 |
| 4 | zhangfei | 22 | 5 |
| 3 | lisi | 19 | 3 |
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 5 | wuhua | 12 | 1 |
+-----+------------+------+----------+
8 rows in set (0.00 sec)E、分组 group by 必须在where之后，order by之前
~~~E.a~~~ select 列名1 from 表 group by 列名1
mysql> select part_nid from a group by part_nid;
+----------+
| part_nid |
+----------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+----------+
5 rows in set (0.00 sec)
~~~E.b~~~ select 列名1,列名2 from 表 group by 列名1,列名2
mysql> select part_nid,age from a group by part_nid,age;
+----------+------+
| part_nid | age |
+----------+------+
| 1 | 12 |
| 2 | 18 |
| 2 | 23 |
| 3 | 19 |
| 4 | 33 |
| 5 | 22 |
| 5 | 33 |
+----------+------+
7 rows in set (0.00 sec)
~~~E.c~~~ select 列名1,列名2 from 表 where 条件1 group by 列名,列名1 order by 列名1 desc
mysql> select part_nid,age from a where age < 30 group by part_nid,age order by age desc;
+----------+------+
| part_nid | age |
+----------+------+
| 2 | 23 |
| 5 | 22 |
| 3 | 19 |
| 2 | 18 |
| 1 | 12 |
+----------+------+
5 rows in set (0.00 sec)
~~~E.d~~~ select 列名1,count(列名2) from 表 group by 列名1
mysql> select part_nid,count(age) from a group by part_nid;
+----------+------------+
| part_nid | count(age) |
+----------+------------+
| 1 | 1 |
| 2 | 3 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
+----------+------------+
5 rows in set (0.00 sec)
~~~E.e~~~ select 列名1 from 表 group by 列名1 having max(列名2) > 条件
mysql> select part_nid from a group by part_nid having max(age) > 30;
+----------+
| part_nid |
+----------+
| 4 |
| 5 |
+----------+
2 rows in set (0.00 sec)
mysql> select * from a;
+-----+------------+------+----------+
| nid | name | age | part_nid |
+-----+------------+------+----------+
| 1 | zhangsan | 18 | 2 |
| 2 | wanwu | 18 | 2 |
| 3 | lisi | 19 | 3 |
| 4 | zhangfei | 22 | 5 |
| 5 | wuhua | 12 | 1 |
| 6 | laohu | 33 | 4 |
| 7 | houyi | 23 | 2 |
| 8 | zhengzheng | 33 | 5 |
+-----+------------+------+----------+
8 rows in set (0.00 sec)
mysql> select * from b;
+-----+-----------+
| nid | caption |
+-----+-----------+
| 1 | it |
| 2 | 驯兽师 |
| 3 | 飞行员 |
| 4 | 清洁员 |
| 5 | 所长 |
| 6 | 经理 |
+-----+-----------+
6 rows in set (0.00 sec)~~~F.a~~~ 关联显示
select A.列名1, A.列名2, B.列名2
from A,B
Where A.列名3 = B.列名3
mysql> select a.nid,a.name,a.age,b.caption from a,b where a.part_nid = b.nid;
+-----+------------+------+-----------+
| nid | name | age | caption |
+-----+------------+------+-----------+
| 5 | wuhua | 12 | it |
| 1 | zhangsan | 18 | 驯兽师 |
| 2 | wanwu | 18 | 驯兽师 |
| 7 | houyi | 23 | 驯兽师 |
| 3 | lisi | 19 | 飞行员 |
| 6 | laohu | 33 | 清洁员 |
| 4 | zhangfei | 22 | 所长 |
| 8 | zhengzheng | 33 | 所长 |
+-----+------------+------+-----------+
8 rows in set (0.00 sec)
~~~F.b~~~ 无对应关系则不显示
select A.列名1, A.列名2, B.列名2
from A inner join B
on A.列名3 = B.列名3
mysql> select a.nid,a.name,a.age,b.caption from a inner join b where a.part_nid = b.nid;
+-----+------------+------+-----------+
| nid | name | age | caption |
+-----+------------+------+-----------+
| 5 | wuhua | 12 | it |
| 1 | zhangsan | 18 | 驯兽师 |
| 2 | wanwu | 18 | 驯兽师 |
| 7 | houyi | 23 | 驯兽师 |
| 3 | lisi | 19 | 飞行员 |
| 6 | laohu | 33 | 清洁员 |
| 4 | zhangfei | 22 | 所长 |
| 8 | zhengzheng | 33 | 所长 |
+-----+------------+------+-----------+
8 rows in set (0.00 sec)
~~~F.c~~~ A表所有显示，如果B中无对应关系，则值为null
select A.列名1, A.列名2, B.列名2
from A left join B
on A.列名3 = B.列名3
mysql> select a.nid,a.name,a.age,b.caption from a left join b on a.part_nid = b.nid;
+-----+------------+------+-----------+
| nid | name | age | caption |
+-----+------------+------+-----------+
| 5 | wuhua | 12 | it |
| 1 | zhangsan | 18 | 驯兽师 |
| 2 | wanwu | 18 | 驯兽师 |
| 7 | houyi | 23 | 驯兽师 |
| 3 | lisi | 19 | 飞行员 |
| 6 | laohu | 33 | 清洁员 |
| 4 | zhangfei | 22 | 所长 |
| 8 | zhengzheng | 33 | 所长 |
+-----+------------+------+-----------+
8 rows in set (0.00 sec)
~~~F.e~~~ B表所有显示，如果B中无对应关系，则值为null
select A.列名1, A.列名2, B.列名2
from A right join B
on A.列名3 = B.列名3
mysql> select a.nid,a.name,a.age,b.caption from a right join b on a.part_nid = b.nid;
+------+------------+------+-----------+
| nid | name | age | caption |
+------+------------+------+-----------+
| 1 | zhangsan | 18 | 驯兽师 |
| 2 | wanwu | 18 | 驯兽师 |
| 3 | lisi | 19 | 飞行员 |
| 4 | zhangfei | 22 | 所长 |
| 5 | wuhua | 12 | it |
| 6 | laohu | 33 | 清洁员 |
| 7 | houyi | 23 | 驯兽师 |
| 8 | zhengzheng | 33 | 所长 |
| NULL | NULL | NULL | 经理 |
+------+------------+------+-----------+
9 rows in set (0.00 sec)
G、组合
~~~G.a~~~ 组合，自动处理重合
select 列名 from A union select 列名 from B
mysql> select nid from a union select nid from b;
+-----+
| nid |
+-----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
+-----+
8 rows in set (0.00 sec)
~~~G.b~~~ 组合，不处理重合
select 列名 from A union all select 列名 from B
mysql> select nid from a union all select nid from b;
+-----+
| nid |
+-----+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
+-----+
14 rows in set (0.00 sec)