• 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? 碧血黄沙


    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)   >   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   peopleId     in   (select     peopleId     from   people     group     by     peopleId       having     count(peopleId)   >   1)  
      and   rowid   not   in   (select   min(rowid)   from     people     group   by   peopleId     having   count(peopleId   )>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(*)   >   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(*)   >   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(*)   >   1)  
      and   rowid   not   in   (select   min(rowid)   from   vitae   group   by   peopleId,seq   having   count(*)>1)  
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  • 原文地址:https://www.cnblogs.com/airfey/p/1542929.html
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