SqlServer刪除重復數據保留一條（好用）

方法一、

1、查詢出重復的數據，Id只保留其中一個

SELECT MIN(Id) Id,Name FROM dbo.City 
GROUP BY Name
HAVING COUNT(1) >  1

2、然后使用刪除時Join上面的表

DELETE C FROM City C 
JOIN (
    SELECT MIN(Id) Id,Name FROM dbo.City
    GROUP BY Name
    HAVING COUNT(1) >  1
) TMP ON C.Name = TMP.Name AND C.Id <> TMP.Id

方法二、

1.查詢單列重復：

select * from test
where name in (select name from test group by name having count
(name) > 1)

2.查詢多列重復

SELECT a.* FROM test a,(
SELECT name,code
FROM test
GROUP BY name,code
HAVING COUNT(1)>1

) AS b
WHERE a.name=b.name AND a.code=b.code