zoukankan      html  css  js  c++  java
  • SQL语句删除表中重复字段

    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)
     
    比方说在A表中存在一个字段“name”,而且不同记录之间的“name”值有可能会相同,
     现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项;
     Select Name,Count(*) From A Group By Name Having Count(*) > 1 
    

      

  • 相关阅读:
    php 框架选择
    转:从框架看PHP的五种境界及各自的薪资待遇(仅限于二三线城市,一线除外)
    百度云怎样提升下载速度
    .net体系与java体系
    绘制3D的js库
    Canvas游戏计算机图形教程
    Unity Manual 用户手册
    在windows系统下安装oracle 11g
    Three.js学习笔记
    php面试题之二——数据结构和算法(高级部分)
  • 原文地址:https://www.cnblogs.com/cyjch/p/2419428.html
Copyright © 2011-2022 走看看