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 程式師世界 >> 數據庫知識 >> SqlServer數據庫 >> 關於SqlServer >> SQL刪除重復數據只保留一條

SQL刪除重復數據只保留一條

編輯:關於SqlServer

       用SQL語句,刪除掉重復項只保留一條

      在幾千條記錄裡,存在著些相同的記錄,如何能用SQL語句,刪除掉重復的呢

      1、查找表中多余的重復記錄,重復記錄是根據單個字段(peopleId)來判斷

      select * from people

      where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

      2、刪除表中多余的重復記錄,重復記錄是根據單個字段(peopleId)來判斷,只留有rowid最小的記錄

      delete from people

      where peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1)

      and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>1)

      3、查找表中多余的重復記錄(多個字段)

      select * from vitae a

      where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

      4、刪除表中多余的重復記錄(多個字段),只留有rowid最小的記錄

      delete from vitae a

      where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

      and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

      5、查找表中多余的重復記錄(多個字段),不包含rowid最小的記錄

      select * from vitae a

      where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

      and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

      6.消除一個字段的左邊的第一位:

      update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'

      7.消除一個字段的右邊的第一位:

      update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'

      8.假刪除表中多余的重復記錄(多個字段),不包含rowid最小的記錄

      update vitae set ispass=-1

      where peopleId in (select peopleId from vitae group by peopleId

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