两个sql having效率高,比我自己写的快30ms,答案更简洁,个人习惯
我写的:
select a.Email from (select Email,count(Email) as num from Person group by Email) as a where a.num > 1
答案:
select Email from Person group by Email having count(Email) > 1
我觉得答案更好,哈哈,很少用having,以后多用用,
两个sql having效率高,比我自己写的快30ms,答案更简洁,个人习惯
我写的:
select a.Email from (select Email,count(Email) as num from Person group by Email) as a where a.num > 1
答案:
select Email from Person group by Email having count(Email) > 1
我觉得答案更好,哈哈,很少用having,以后多用用,