SQL删除重复数据只保留一条

ゞ浴缸里的玫瑰 2022-05-24 07:58 203阅读 0赞

用SQL语句,删除掉重复项只保留一条

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 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 * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) &gt; 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 delete from people where&nbsp;&nbsp; peopleName in (select peopleName&nbsp;&nbsp;&nbsp; from people group by peopleName&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; having count(peopleName) &gt; 1) and&nbsp;&nbsp; peopleId not in (select min(peopleId) from people group by peopleName&nbsp;&nbsp;&nbsp;&nbsp; having count(peopleName)&gt;1) 3、查找表中多余的重复记录（多个字段） select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) &gt; 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 delete from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) &gt; 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)&gt;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 * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) &gt; 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)&gt;1)&nbsp;&nbsp;&nbsp; 
 6.消除一个字段的左边的第一位： 
 update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%' 
 7.消除一个字段的右边的第一位： 
 update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%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 update vitae set ispass=-1 where peopleId in (select peopleId from vitae group by peopleId 
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