Original link:
http://www.cnblogs.com/enhance/p/10980459.html
| id | name | id | name |
| 1 | zhangsan | 1 | hanmeimei |
| 2 | lysis | 2 | wangwu |
| 3 | wangwu |
join:select * from A join B on A.name=B.name -----取交集
| id | name | id | name |
| 1 | wangwu | 2 | wangwu |
full/out join:select * from A full join B on A.name=B.name ----取并集
| id | name | id | name |
| 1 | zhangsan | null | null |
| 2 | lysis | null | null |
| 3 | wangwu | 2 | wangwu |
| null | null | 1 | hanmeimei |
left join:select * from A left join B on A.name=B.name
| id | name | id | name |
| 1 | zhangsan | null | null |
| 2 | lysis | null | null |
| 3 | wangwu | 2 | wangwu |
right join: select * from A right join B on B.name
| id | name | id | name |
| null | null | 1 | hanmeimei |
| 3 | wangwu | 2 | wangwu |
union: select name from A union select name from B (union and in the union all select statement queries require the same column)
| name |
| zhangsan |
| lysis |
| wangwu |
| hanmeimei |
union all: the difference is more union union will merge duplicate values, but does not merge union all
select name from A union all select name from B
| name | ||||
|
||||
| wangwu |
Reproduced in: https: //www.cnblogs.com/enhance/p/10980459.html