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        SQL刪除重復(fù)數(shù)據(jù)只保留一條

        字號(hào):


            用SQL語(yǔ)句,刪除掉重復(fù)項(xiàng)只保留一條
            在幾千條記錄里,存在著些相同的記錄,如何能用SQL語(yǔ)句,刪除掉重復(fù)的呢
            1、查找表中多余的重復(fù)記錄,重復(fù)記錄是根據(jù)單個(gè)字段(peopleId)來(lái)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(fù)記錄,重復(fù)記錄是根據(jù)單個(gè)字段(peopleId)來(lái)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(fù)記錄(多個(gè)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(fù)記錄(多個(gè)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(fù)記錄(多個(gè)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(gè)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(gè)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(fù)記錄(多個(gè)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