提高查詢性能

Question

我的查詢花了很長時間。

select distinct JobName,
       ValidationType,
       AppName,
       Result,
       ResultType,
       ErrorWarningDetails,
       CvtStartDateTime 
  from contentvalidationjobdetails with (nolock)
 where appname=@AppName 
       and result=@Result 
       and (cast(cvtstartdatetime as date) > @Date )
       and concat(Jobname,validationtype) not in (
                  select concat(jobname,validationtype) 
                    from Contentvalidationjobdetails with (nolock) 
                   where appname = @AppName 
                         and CVTStartDateTime = (
                          select top 1 teststartdatetime 
                            from contentvalidation 
                           where appname=@AppName 
                                 and Teststartdatetime<@Date
                        order by teststartdatetime desc
                         )
           )

我知道concat（jobname，validationtype）需要時間。 如何處理。

Answer 1

將查詢放在FROm節中僅執行一次（而不是針對WHERE中的每一行）。 添加外部聯接，僅保留沒有聯接的記錄。

select distinct JobName,
       ValidationType,
       AppName,
       Result,
       ResultType,
       ErrorWarningDetails,
       CvtStartDateTime 
  from contentvalidationjobdetails with (nolock)
       LEFT OUTER JOIN (
                  select concat(jobname,validationtype) cnt
                    from Contentvalidationjobdetails with (nolock) 
                   where appname = @AppName 
                         and CVTStartDateTime = (
                          select top 1 teststartdatetime 
                            from contentvalidation 
                           where appname=@AppName 
                                 and Teststartdatetime<@Date
                        order by teststartdatetime desc) sub ON concat(Jobname,validationtype)=sub.cnt

 where appname=@AppName 
       and result=@Result 
       and (cast(cvtstartdatetime as date) > @Date ))
  HAVING sub.cnt is null