Question

sql server如何知道表中是否有重复的记录行

Answer 1

例如数据库中有两个字段A，B，则用下面的语句查出是否有重复数据
select A,B from table1 group by A,B having count(*) > 1;

Answer 2

一个表是否有重复 请用 count() 和group by
2个表是否存在用exists

Answer 3

如：想知道表中col1,col2是否有重复资料，哪些资料重复可以用如下方法
select col1,col2 from table1 group by col1,col2 having count(*) > 1;

Answer 4

查询重复行
select 列 from 表 GROUP BY 列 having count( 列)>1
删除重复行
delete from 表 where 列 in (select 列 from 表 GROUP BY 列 having count( 列)>1)

Answer 5

select count(*),count(distinct colname) from table