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sql查询表中重复数据

查询重复数据,方法如下:select * from [表A] where id in (select id from [表A] group by id having count(id) >1 )

select count(name) c,name from student where c>1 不知道sql对不对 思路应该没问题 应该会报 不是分组 的错误吧调一调 select count(name) c,max(name) from student group by name having c>1 ??自己调一调吧,应该差不多

这个查找过程分两步走:1、找出这列中有相同内容的记录.代码如下:select 列名 from 表名 group by 列名 having count(列名) > 12、把这些有相同内容的记录,查出来.代码如下:select 列名 from 表名 where 列名 in (select 列名 from 表名 group by 列名 having count(列名) > 1) 这些我已经调试过了

两种写法,一是嵌套查询 select * from 表2 where d in (select a from 表1 where b=5); 二是关联查询 select 表2.* from 表1,表2 where 表1.b=5 and 表1.a=表2.d;

如果后面地址都是一样,那么还可以这样 select * from 表A where name in (select distinct name from 表B ) 或者用Group by 也行

select count(*) from 表 where 字段=数据

select col001,count(col001) from lhsjb where count(col001) > 1 group by col001

如统计班级和班级人数,语句:select ID,NAME,AGE,GREADE,班级人数 from A inner join( select GREADE,sum(id) 班级人数 from A group by GREADE) b on A.GREADE = b.GREADE

查询重复 select [需要排重的列名] from 表名 group by [需要排重的列名] having count(1)>1删除重复 delete from 表名 where [id自增列] in ( select [id自增列] from 表名 a where [需要排重的列名] in ( select [需要排重的列名] from 表名 b where a.id自增列 >= b.id自增列 group by [需要排重的列名] having count(1)>1 ) )删除的时候注意,里面的[表名]针对的是同一张表,此表最好有一个自增列

select max(a),max(b)等字段 from A group by a,b,c,d max 是聚合函数 如果值是数字 建议换个聚合函数就行

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