mysql-查询结果去重

2022-08-03 90 阅读1分钟

select distinct job from emp
distinct关键字去除关键字

mysql> select distinct job from emp;
+-----------+
| job       |
+-----------+
| CLERK     |
| SALESMAN  |
| MANAGER   |
| ANALYST   |
| PRESIDENT |
+-----------+
5 rows in set (0.00 sec)

mysql> select ename, distinct job from emp;
上面是错的，distinck
只能出现所有字段最前边，联合去重

mysql> select count(distinct job)  from emp;
+---------------------+
| count(distinct job) |
+---------------------+
|                   5 |
+---------------------+
1 row in set (0.01 sec)

去重之后统计数量