现在有两个表格，用来演示表格的内连接、做连接及右连接；
A表
| id | name |
| 1 | a |
| 2 | b |
| 3 | c |
| 4 | d |
| 5 | e |
| 6 | f |
B表
| id | name |
| 1 | 白 |
| 2 | 黑 |
| 3 | 红 |
| 4 | 绿 |
| 5 | 蓝 |
内连接：select * from A,B where A.id=B.id与Select * from A JOIN B ON A.id=B.id
结果
| id | name | id | name |
| 1 | a | 1 | 白 |
| 2 | b | 2 | 黑 |
| 3 | c | 3 | 红 |
| 4 | d | 4 | 绿 |
| 5 | e | 5 | 蓝 |
左连接：select * from A Left JOIN B ON A.id=B.id
| id | name | id | name |
| 1 | a | 1 | 白 |
| 2 | b | 2 | 黑 |
| 3 | c | 3 | 红 |
| 4 | d | 4 | 绿 |
| 5 | e | 5 | 蓝 |
| 6 | f | null | null |