SQL问题 -- 多列去重 日常总结

SQL问题 – 去重日常

写个随笔，去重问题

多列去重并且有重复的

	select CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO
    FROM order 
    group by CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO 
    HAVING count(*) > 1

这两个是重复的

多列查重

    select CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO FROM 
 	order WHERE (CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO)
    in (select CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO FROM order 
    group by CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO 
    HAVING count(*) > 1)

DISTINCT 关键字

多列去重唯一的

select DISTINCT CUSTOMER_NAME,CUSTOMER_CODE,CONTRACT_NO 
FROM order