mysql查詢某個字段中是否有重復的值

方法一

SELECT *
FROM (

SELECT `openid` , COUNT( * ) AS c
FROM ing_jf_shop
GROUP BY `openid`

)t
WHERE c >1

方法二

SELECT openid ,
        COUNT(openid)
FROM  ing_jf_shop
GROUP BY openid
HAVING  COUNT(openid) > 1

 

-- ing_jf_shop 是表名

-- openid 是要確定是否有重復值的字段