java _sql union
2021-01-15 本文已影响0人
走停2015_iOS开发
-
union
可以将查询结果集相加
//找出工作岗位是AAAA和BBB的员工
1.select name,job from t_user where job = 'AAAA' or job = 'BBB';
2.select name,job from t_user where job in('AAAA','BBB');
//把俩张查询结果相加
3.select name,job from t_user where job = 'AAAA' union select name,job from t_user where job = 'BBB';
+-----------+------+
| name | job |
+-----------+------+
| HanMeimei | AAAA |
| ZhangWei | AAAA |
| Lucy | BBB |
| WeiHua | BBB |
+-----------+------+
- 俩张不相干的表中的数据拼接在一起显示
select name from t_user union select dname from dept;
+-----------+
| name |
+-----------+
| Ann |
| HanMeimei |
| Ka_te |
| Lisa |
| Lucy |
| WeiHua |
| ZhangWei |
| ZWei |
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| 开发部 |
| 市场部 |
| 设计部 |
| 采购部 |