前兩天做系統調優的時候，想著把一系列的表聯合查詢換成視圖查詢，這樣速度就會快些，但是效果卻不是很理想。下面我把相關實驗過程記錄下來。

原sql語句是一個表聯合查詢，WorkOrder表數據有200多萬條。下面代碼是一個是聯合查詢，一個是將聯合查詢建成一個視圖。

declare @d1 datetime
declare @d2 datetime
set @d1=getdate()
   --聯合查詢
   SELECT WO.WorkOrderCode,WO.WorkOrderType,WO.Status,WO.CustName,WO.CustTel1,WO.CustTel2,WO.CustIdentityNo,WO.CardId,WO.CustSex,WO.CustAge,WO.CustBirthday, WO.IsMember,WO.AccountLevel,WO.MemberDate,WO.AccountScore,WO.DestTarget,WO.DestTargetDesc,WO.Source,WO.ToType,WO.Dept,WO.HotelId,WO.HotelName, WO.HotelCreateDate,WO.HotelType,WO.HotelBrand,WO.HotelTel,WO.HotelBigArea,WO.HotelArea,WO.HotelCityGroup,‘‘
 
 AS HotelCity,WO.Title,WO.SelectTitle,WO.Content,WO.IsAccept,WO.CompensateDept, WO.CompensateAmountType,WO.CompensateAmount,WO.ReferDept,WO.ResponsiblePerson,W2.Attribute3 AS ResponsiblePersonName,WO.ResponsibleDate,WO.ClosePerson, WO.CloseDate,WO.CatePerson,WO.CateDate,WO.ScorePerson,WO.ScoreDate,WO.CreateUser,WO.CreateDate,WO.UpdateUser,WO.UpdateDate,W1.Attribute3 AS
 
 UserName   FROM WorkOrder WO WITH (NOLOCK)  LEFT JOIN WSCUser W1 ON WO.CreateUser=W1.UserID  LEFT JOIN WSCUser W2 ON WO.ResponsiblePerson=W2.UserID  
      WHERE 1=1    AND WO.STATUS=3 AND WO.WorkOrderType=‘T‘   
 
select [語句執行花費時間(毫秒)]=datediff(ms,@d1,getdate())
    
set @d2=getdate()     
   --視圖查詢
 

 SELECT WO.WorkOrderCode,WO.WorkOrderType,WO.Status,WO.CustName,WO.CustTel1,WO.CustTel2,WO.CustIdentityNo,WO.CardId,WO.CustSex,WO.CustAge,WO.CustBirthday, WO.IsMember,WO.AccountLevel,WO.MemberDate,WO.AccountScore,WO.DestTarget,WO.DestTargetDesc,WO.Source,WO.ToType,WO.Dept,WO.HotelId,WO.HotelName, WO.HotelCreateDate,WO.HotelType,WO.HotelBrand,WO.HotelTel,WO.HotelBigArea,WO.HotelArea,WO.HotelCityGroup,‘‘ AS HotelCity,WO.Title,WO.SelectTitle,WO.Content,WO.IsAccept,WO.CompensateDept, WO.CompensateAmountType,WO.CompensateAmount,WO.ReferDept,WO.ResponsiblePerson,  ResponsiblePersonName,WO.ResponsibleDate,WO.ClosePerson, WO.CloseDate,WO.CatePerson,WO.CateDate,WO.ScorePerson,WO.ScoreDate,WO.CreateUser,WO.CreateDate,WO.UpdateUser,WO.UpdateDate,  WO.UserName   FROM 
 V_WorkOrder_WSCUser wo WHERE 1=1    AND WO.STATUS=3 AND WO.WorkOrderType=‘T‘                    
    

select [語句執行花費時間(毫秒)]=datediff(ms,@d2,getdate())

　　我執行了5次這段代碼，5次結果如下。

　　看到這五次執行時間的對比，發現視圖對查詢效率並沒有提高，再看執行計劃，也是一樣。

所以總結一下，視圖對於查詢效率的提升相對於聯合查詢來說，並沒有提升，對開發效率有提升。

最後，國慶節中秋節，雙節快樂。

參考：關於視圖 和存儲過程效率的問題

T-SQL查詢進階--深入淺出視圖

視圖查詢性能的新認識