视图查询性能的新认识

　　前两天做系统调优的时候，想着把一系列的表联合查询换成视图查询，这样速度就会快些，但是效果却不是很理想。下面我把相关实验过程记录下来。

原sql语句是一个表联合查询，WorkOrder表数据有200多万条。下面代码是一个是联合查询，一个是将联合查询建成一个视图。

declare @d1 datetime
declare @d2 datetime
set @d1=getdate()
   --联合查询
   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 [语句执行花费时间(毫秒)]=datediff(ms,@d1,getdate())

set @d2=getdate()
   --视图查询
 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 [语句执行花费时间(毫秒)]=datediff(ms,@d2,getdate())

　　我执行了5次这段代码，5次结果如下。

　　看到这五次执行时间的对比，发现视图对查询效率并没有提高，再看执行计划，也是一样。

所以总结一下，视图对于查询效率的提升相对于联合查询来说，并没有提升，对开发效率有提升。

最后，国庆节中秋节，双节快乐。

参考：关于视图 和存储过程效率的问题

T-SQL查询进阶--深入浅出视图