SQL语句实现删除重复记录并只保留一条
deleteWeiBoTopicswhereIdin(selectmax(Id)fromWeiBoTopicsgroupbyWeiBoId,TitlehavingCOUNT(*)>1);
SQL：删除重复数据，只保留一条用SQL语句,删除掉重复项只保留一条在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断
select*frompeoplewherepeopleIdin(selectpeopleIdfrompeoplegroupbypeopleIdhavingcount(peopleId)>1)
2、删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录
deletefrompeoplewhere peopleNamein(selectpeopleName frompeoplegroupbypeopleName havingcount(peopleName)>1)and peopleIdnotin(selectmin(peopleId)frompeoplegroupbypeopleName havingcount(peopleName)>1)
3、查找表中多余的重复记录（多个字段）
select*fromvitaeawhere(a.peopleId,a.seq)in(selectpeopleId,seqfromvitaegroupbypeopleId,seqhavingcount(*)>1)
4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录
deletefromvitaeawhere(a.peopleId,a.seq)in(selectpeopleId,seqfromvitaegroupbypeopleId,seqhavingcount(*)>1)androwidnotin(selectmin(rowid)fromvitaegroupbypeopleId,seqhavingcount(*)>1)
5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录
select*fromvitaeawhere(a.peopleId,a.seq)in(selectpeopleId,seqfromvitaegroupbypeopleId,seqhavingcount(*)>1)androwidnotin(selectmin(rowid)fromvitaegroupbypeopleId,seqhavingcount(*)>1)
6.消除一个字段的左边的第一位：
updatetableNameset[Title]=Right([Title],(len([Title])-1))whereTitlelike'村%'
7.消除一个字段的右边的第一位：
updatetableNameset[Title]=left([Title],(len([Title])-1))whereTitlelike'%村'
8.假删除表中多余的重复记录（多个字段），不包含rowid最小的记录
updatevitaesetispass=-1wherepeopleIdin(selectpeopleIdfromvitaegroupbypeopleId,seqhavingcount(*)>1)andseqin（selectseqfromvitaegroupbypeopleId,seqhavingcount(*)>1）androwidnotin(selectmin(rowid)fromvitaegroupbypeopleId,seqhavingcount(*)>1)
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