1.根据emp数据表编写SQL查出所有name重复的记录且按照age降序。
+——–+——–+—–+
| emp_no | name | age |
+——–+——–+—–+
| 1001 | 小明 | 18 |
| 1002 | 王强 | 20 |
| 1003 | 小雪 | 20 |
| 1004 | 小明 | 19 |
+——–+——–+—–+
select emp_no, name,age from emp where name in ( select t.name from ( select name,count(name) as num from emp group by name having num > 1 )t ) order by age desc;