SQLServer獲取重復(fù)數(shù)據(jù)的方法

SQL Server獲取重復(fù)數(shù)據(jù)的方法
    一 獲取重復(fù)的數(shù)據(jù)的值
    select user_name from users
    group by user_name
    having(count(1)>1)
    二 獲取重復(fù)數(shù)據(jù)的記錄
    select * from users where user_name in
    (
    select user_name from users
    group by user_name
    having(count(1)>1)
    )
    三 獲取多余的重復(fù)數(shù)據(jù)
    select * from users where user_name not in
    (
    select max(user_name) from users
    group by user_name
    having(count(1)>1)
    )