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sql语句查询重复数据

可用group by……having来实现。 可做如下测试: 1、创建表插入数据: create table test(id int,name varchar(10))insert into test values (1,'张三')insert into test values (2,'李四')insert into test values (3,'张三')insert into test va...

select * from tablename where 重复字段1 in (select 重复字段1 from tablename group by 重复字段1,重复字段2 having count(*)>1)

SELECT 某一列, COUNT( 某一列 ) FROM 表 GROUP BY 某一列 HAVING COUNT( 某一列 ) 〉1 这样查询出来的结果, 就是 有重复, 而且 重复的数量。

1、最直观的思路:要知道所有名字有重复人资料,首先必须知道哪个名字重复了: select name from emp group by name having count(*)>1 所有名字重复人的记录是: select * from emp where name in (select name from emp group by name having c...

SELECT * FROM tab WHERE C in ( SELECT C FROM tab GROUP BY C HAVING COUNT(A) > 1 )

select a,b,c,d,count(*) from table group by a,b,c,d count(*)就是重复数

select a.* from table1 a where a. 姓名 in(select distinct 姓名 from table2)

使用DISTINCT关键字可以查询去除重复数据,例如:SELECT DISTINCT t1 FROM table1,t1存在相同的则会去掉不会显示

select b from A group by b having count (*)>1

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