数据为
+---------------+---------------+---------------+
| ID | TYPE | REMARK |
+---------------+---------------+---------------+
| 1 | 1 | A |
| 2 | 2 | B |
| 3 | 3 | C |
| 4 | 1 | D |
| 5 | 3 | E |
+---------------+---------------+---------------+
期待结果为:
+---------------+---------------+---------------+
| ID | TYPE | REMARK |
+---------------+---------------+---------------+
| 1 | 1 | A |
| 2 | 2 | B |
| 3 | 3 | C |
+---------------+---------------+---------------+
主要是想查询出 TYPE 无重复数据。重复的忽略......
+---------------+---------------+---------------+
| ID | TYPE | REMARK |
+---------------+---------------+---------------+
| 1 | 1 | A |
| 2 | 2 | B |
| 3 | 3 | C |
| 4 | 1 | D |
| 5 | 3 | E |
+---------------+---------------+---------------+
期待结果为:
+---------------+---------------+---------------+
| ID | TYPE | REMARK |
+---------------+---------------+---------------+
| 1 | 1 | A |
| 2 | 2 | B |
| 3 | 3 | C |
+---------------+---------------+---------------+
主要是想查询出 TYPE 无重复数据。重复的忽略......
from tb
group by type
having count(*)=1
from 数据 a
where not exists(select 1 from 数据 where TYPE=a.TYPE and ID<a.ID_
select *
from 数据 a
group by TYPE
这个如何呢?