l in (SELECT col FROM table GROUP BY col HAVING COUNT (col) >1);
顺带说一下where和having：
select * from tablewhere ···(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
sql查询某字段的相同值
sql查询某字段的相同值:
SELECT * FROM table WHERE co
l 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
l in (SELECT col FROM table GROUP BY col HAVING COUNT (col) >1);
顺带说一下where和having：
select * from tablewhere ···(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
