楼主请看测试结果: select * from a ----------------------------------------- id name ---------- ---------- 1 tom 2 mary 3 tom 4 tom 5 mary 6 jack 7 jack 8 mary (所影响的行数为 8 行)根据(宝宝)所说:select count(distinct(name)) from a ------------------------------------------------------- ----------- 3(所影响的行数为 1 行) 至于你所说的每一个组取一个记录,如果有自增列,或者ID的话,是比较好搞的,不然可以用临时表来增加一自增列来进行处理 select min(id),name from a group by name ------------------------------------------------------ name ---------- ---------- 6 jack 2 mary 1 tom (所影响的行数为 3 行)
select * from a
-----------------------------------------
id name
---------- ----------
1 tom
2 mary
3 tom
4 tom
5 mary
6 jack
7 jack
8 mary (所影响的行数为 8 行)根据(宝宝)所说:select count(distinct(name)) from a
-------------------------------------------------------
-----------
3(所影响的行数为 1 行)
至于你所说的每一个组取一个记录,如果有自增列,或者ID的话,是比较好搞的,不然可以用临时表来增加一自增列来进行处理
select min(id),name from a group by name
------------------------------------------------------
name
---------- ----------
6 jack
2 mary
1 tom (所影响的行数为 3 行)
from table
group by 字段