添加示例數(shù)據(jù)

create table Student(ID varchar(10) not null,Name varchar(10) not null,);insert into Student values("1", "zhangs");insert into Student values("2", "zhangs");insert into Student values("3", "lisi");insert into Student values("4", "lisi");insert into Student values("5", "wangwu");

刪除Name重復(fù)多余的行,每個Name僅保留1行數(shù)據(jù)

1、查詢表中Name 重復(fù)的數(shù)據(jù)

select Name from Student group by  Name having count(Name) > 1

2、有唯一列，通過唯一列最大或最小方式刪除重復(fù)記錄

檢查表中是否有主鍵或者唯一值的列，當前可以數(shù)據(jù)看到ID是唯一的，可以通過Name分組排除掉ID最大或最小的行

delete from Student  where Name in( select Name from Student group by  Name having count(Name) > 1) and  ID not in(select  max(ID) from Student group by  Name having count(Name) > 1 )

執(zhí)行刪除腳本后查詢

3、無唯一列使用ROW_NUMBER()函數(shù)刪除重復(fù)記錄

如果表中沒有唯一值的列，可以通過row_number 來刪除重復(fù)數(shù)據(jù)
重復(fù)執(zhí)行插入腳本，查看表數(shù)據(jù)，表中沒有唯一列值

Delete T From (Select Row_Number() Over(Partition By [Name] order By [ID]) As RowNumber,* From Student)T Where T.RowNumber > 1

小知識點

語法：ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)
表示根據(jù)COLUMN分組，在分組內(nèi)部根據(jù) COLUMN排序，而此函數(shù)計算的值就表示每組內(nèi)部排序后的順序編號（組內(nèi)連續(xù)的唯一的)
函數(shù)“Row_Number”必須有 OVER 子句。OVER 子句必須有包含 ORDER BY
Row_Number() Over(Partition By [Name] order By [ID]) 表示已name列分組，在每組內(nèi)以ID列進行升序排序，每組內(nèi)返回一個唯一的序號

執(zhí)行刪除腳本后查詢表數(shù)據(jù)

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