一般來說,連接的效率會高於子查詢. 用*號查詢時會繞過索引,降第效率. 所以改為: select 字段 from fgzren as a inner join (Select 版号 From fgzren as b inner join (Select 版号 From fgzren Group By 版号,返工时间) as c on c.版号=b.版号 Group By b.版号 Having Count(*) >1 ) as d on a.版号=d.版号 (沒有測試)
Select * From fgzren Group By 版号 having count(*)>1
Select 版号 From fgzren Group By 版号,返工时间 这句话肯定不对,select后没有“返工时间”GBroup By肯定出错
用*號查詢時會繞過索引,降第效率.
所以改為:
select 字段
from fgzren as a inner join (Select 版号 From fgzren as b inner join (Select 版号 From fgzren Group By 版号,返工时间) as c on c.版号=b.版号 Group By b.版号 Having Count(*) >1 ) as d on a.版号=d.版号
(沒有測試)
Group By 版号
having count(*)>1
这句话肯定不对,select后没有“返工时间”GBroup By肯定出错