sql查询某字段的相同值:
SELECT * FROM table WHERE col in (SELECT col FROM table GROUP BY col HAVING COUNT (col) >1);
顺带说一下where和having:
select * from table
where ···(只能对分组前的属性进行筛选)
group by ···(按某个字段分组)
having ···(只能对分组后的每个组的整体属性进行筛选,用聚合函数体现)
--不使用group by就默认表的整体为一组
实例:
查询出重复记录
select * from 数据表 WHERE 重复记录字段 in ( select 重复记录字段 from 数据表 group by 重复记录字段 having count(重复记录字段)>1)