MySQL检查值是否存在多次

Question

我有MySQL数据库,并有一个名为CALLER的表.在表调用程序中,我需要检查USERNAME列中是否存在多次存在的值,如果存在则列出所有这些值.

谢谢

Answer 1

通常你可以使用GROUP BY和HAVING COUNT(*)>1

SELECT USERNAME FROM CALLER
GROUP BY USERNAME 
HAVING COUNT(*)>1

更新:获取所有重复的行:

SELECT * FROM CALLER WHERE USERNAME IN
  ( 
    SELECT USERNAME FROM CALLER
    GROUP BY USERNAME 
    HAVING COUNT(*)>1
  )