oracle基础积累-join,left join,right join,inner join,full join,left outer join,right outer join 之间的区别

场景:
基础知识查询.
环境:
Oracle Database 11g; PL/SQL Developer
1.表数据
1.1 传感器采集区域 sensor_collect_region

1.2 传感器采集数据 sensor_collect_data

2. join
两张表根据on条件进行连接查询,查询出两张表完全匹配的结果集.

select *
  from sensor_collect_data aa
  join sensor_collect_region bb
    on aa.region = bb.region

3. left join (左连接)
两张表根据on条件进行左连接查询,会返回left join左边表所有行,即使右表没有匹配记录.

select *
  from sensor_collect_data aa
  left join sensor_collect_region bb
    on aa.region = bb.region

4. right join (右连接)
两张表根据on条件进行右连接查询,会返回right join右边表所有行,即使左表没有匹配记录.

select *
  from sensor_collect_data aa
 right join sensor_collect_region bb
    on aa.region = bb.region

5. inner join (内连接)
两张表根据on条件进行内连接查询,查询出两张表完全匹配的结果集.

select *
  from sensor_collect_data aa
 inner join sensor_collect_region bb
    on aa.region = bb.region

6. full join (全连接)
两张表根据on条件进行连接查询,返回左表和右表中所有记录,包括没有匹配的记录.

select *
  from sensor_collect_data aa
  full join sensor_collect_region bb
    on aa.region = bb.region

7. left outer join
与left join相同

select *
  from sensor_collect_data aa
  left outer join sensor_collect_region bb
    on aa.region = bb.region

8. right outer join
right join 相同

select *
  from sensor_collect_data aa
 right outer join sensor_collect_region bb
    on aa.region = bb.region

9. 左连接和右连接进行union操作

select *
  from sensor_collect_data aa
  left join sensor_collect_region bb
    on aa.region = bb.region
union
select *
  from sensor_collect_data aa
 right join sensor_collect_region bb
    on aa.region = bb.region

10. 结论
join和inner join等价
left join和left outer join等价
right join和right outer join等价
left join与right join进行union操作和full join等价
11.附建表语句
11.1 建表语句一

create table SENSOR_COLLECT_DATA
(
  sensor_id NUMBER(16) not null,
  region    VARCHAR2(16) not null,
  s1        NUMBER(6,3),
  s2        NUMBER(6,3),
  s3        NUMBER(6,3)
);
comment on table SENSOR_COLLECT_DATA
  is '传感器采集数据';
comment on column SENSOR_COLLECT_DATA.sensor_id
  is '数据id实体唯一标识';
comment on column SENSOR_COLLECT_DATA.region
  is '传感器安装区域';
comment on column SENSOR_COLLECT_DATA.s1
  is '传感器采集的值1';
comment on column SENSOR_COLLECT_DATA.s2
  is '传感器采集的值2';
comment on column SENSOR_COLLECT_DATA.s3
  is '传感器采集的值3';
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191502, '2019', 12, 33, 55);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191514, '2018', 22, 33, 5);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191513, '2018', 2, 3, 66);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191515, '2028', 8, 56, 77);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191517, '2017', 22, 33, 33);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191516, '2017', 22.22, 33.33, 55.33);
insert into SENSOR_COLLECT_DATA (sensor_id, region, s1, s2, s3)
values (20191501, '2019', 12.88, 888.55, 3.22);
commit;

11.2 建表语句二

create table sensor_collect_region
(
  region         VARCHAR2(16) not null,
  region_name    VARCHAR2(128),
  region_type    VARCHAR2(128)
);
comment on table sensor_collect_region
  is '传感器采集区域';
comment on column sensor_collect_region.region
  is '传感器安装区域,实体唯一标识';
comment on column sensor_collect_region.region_name
  is '名称';
comment on column sensor_collect_region.region_type
  is '类型';
insert into SENSOR_COLLECT_REGION (region, region_name, region_type)
values ('2017', '江苏', '1');
insert into SENSOR_COLLECT_REGION (region, region_name, region_type)
values ('2018', '福建', '2');
insert into SENSOR_COLLECT_REGION (region, region_name, region_type)
values ('2019', '浙江', '1');
insert into SENSOR_COLLECT_REGION (region, region_name, region_type)
values ('2016', '黑龙江', '3');
commit;

以上,感谢.

zhangbeizhen18

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oracle基础积累-join,left join,right join,inner join,full join,left outer join,right outer join 之间的区别

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