Question

是否有更有效的方法来编写此SQL查询？

它在大约45秒内从一组100,000行中返回大约800行。

我使用的是Sql Server 2008 R2

Select a.Div as Division
      ,a.Room as RoomLocation
      ,a.Form as Forms
      ,a.Nums as TotalNumberLocations
From AView a
Where a.Id = '1'
And a.Div = 'A'
Group By a.Div, a.Nums, a.Room, a.Form

union

Select b.Div as Division
      ,b.Room as RoomLocation
      ,b.Form as Forms
      ,b.Nums as TotalNumberLocations
From AView b
Where b.Id = '1'
And b.Div = 'G'
Group By b.Div, b.Nums, b.Room, b.Form

union

Select c.Div as Division
      ,c.Room as RoomLocation
      ,c.Form as Forms
      ,c.Nums as TotalNumberLocations
From AView c
Where c.Id = '1'
And c.Div = 'R'
Group By c.Div, c.Nums, c.Room, c.Form
Order By Forms asc, TotalNumberLocations asc

Answer 1

为什么在IN子句中拥有值时可以使用UNION？你正在扫描桌子三次。

Select Div as Division
      ,Room as RoomLocation
      ,Form as Forms
      ,Nums as TotalNumberLocations
From AView 
Where Id = '1'
And Div IN ('A','G','R')
Group By Div, Nums, Room, Form
Order By Forms asc, TotalNumberLocations asc

Answer 2

与the other answer类似，但您也可以将GROUP BY替换为distinct

Select distinct Div as Division
      ,Room as RoomLocation
      ,Form as Forms
      ,Nums as TotalNumberLocations
From AView a
Where Id = '1'
And Div in ('A', 'G', 'R')
Order By Forms asc, TotalNumberLocations asc

Answer 3

我认为表Id的列Div和AView的索引对于此查询的性能非常有用，可能更多的是重写查询。

高效的SQL查询

3 个答案: