Question

我们需要在网页中实现搜索功能。所以我们创建了一个存储过程来检索记录。逻辑是，当我选择输入参数时，Sp返回参数的过滤记录，否则它将检索所有可用记录。

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例如：如果我给，

EXEC [WB_GetClassesByLocation_new2] null,null,null,'null',null,NULL,'N','N','N','N','N','N','N',NULL,null,null,null,null,null

（N是Days字段的默认值） SP将返回所有可用记录。如果我给，

EXEC [WB_GetClassesByLocation_new2] 1000,null,null,'null',null,NULL,'N','N','N','N','N','N','N',NULL,null,null,null,null,null。 SP将返回1000区的记录。我已实现以下逻辑

Select distinct c.classID, co.fCourseName as CourseName, StreetAddress + ', ' + l.City as LocationAddress, s.SessionName, sh.fShift as shift, StartTime, EndTime, c.classname, s.SessionID,
        c.StartDate,c.enddate 
        From dbo.vw_Class c 
        Inner Join dbo.lk_Session s 
        On (s.SessionID = c.sessionID) 
        Inner Join dbo.lk_Course co 
        On (co.CourseID = c.CourseID )
        Inner Join dbo.vw_Location l 
        On (l.locationid = c.locationid) 
        Inner Join lk_District d
        On (d.districtID = c.districtId) 
        Inner Join lk_Province p 
        On (p.provik = d.provik) 
        Inner Join lk_Shift sh 
        On (c.shiftid = sh.shiftid)
       where 
          c.DistrictID       =  case  when @Districtid is null   then c.DistrictID   else  @Districtid  end 
         and c.LocationID    =  case  when @locationid is null   then c.LocationID   else  @locationid  end 
         and s.SessionID     =  case  when @sessionid is null    then s.SessionID    else  @sessionid   end 
         and c.CourseID      =  case  when @levelid  is null     then c.CourseID     else  @levelid     end 
         and c.ShiftID       =  case  when @shiftid   is null    then c.ShiftID      else  @shiftid     end 
         and c.StartDate    >=  case  when @startdate is null    then c.StartDate    else  @startdate   end
         and c.EndDate      <=  case when  @enddate is null      then c.EndDate      else  @enddate     end
         and convert(time,c.StartTime) >= case when @starttime is null then convert(time,c.StartTime) else convert(time,@starttime) end
         and convert(time,c.endtime)   <= case when @endtime is null then convert(time,c.endtime) else convert(time,@endtime) end
         and c.Monday    = case  when @day1 = 'N' then c.monday     else  @day1  end 
         and c.Tuesday   = case  when @day2 = 'N' then c.Tuesday        else  @day2  end 
         and c.Wednesday = case  when @day3 = 'N' then c.Wednesday  else  @day3  end 
         and c.Thursday  = case  when @day4 = 'N' then c.Thursday       else  @day4  end 
         and c.Friday    = case  when @day5 = 'N' then c.Friday     else  @day5  end 
         and c.Saturday  = case  when @day6 = 'N'then c.Saturday        else  @day6  end 
         and c.Sunday    = case  when @day7 = 'N' then c.Sunday     else  @day7  end 
         and c.RowStatus    = 'A' 
         ORDER BY co.fCourseName, s.SessionID ,c.ClassName

但Sp需要花费太多时间来执行。这是在sql server中实现“All IF null”逻辑的正确方法吗？还有其他方法吗？

Answer 1

以下是我的表现方式：

( @Districtid is null OR c.DistrictID = @Districtid )
AND
( @Locationid is null OR c.LocationID = @Locationid )
AND
...

但是，当您拥有非常多的这些过滤器，并且您已经接近我要尝试的临界点时，您最好不要创建动态SQL查询。

Answer 2

如果你有很多过滤器的查询，我知道2个选项：

使用OR（如上所述），这可能导致查询优化器扫描表。有关详细信息，请参阅此帖子：How to Optimize the Use of the "OR" Clause When Used with Parameters (SQL Server 2008)

使用动态SQL - 这可能导致查询优化器计算每个参数中每次更改的执行计划一个很好的选择是使用Bind Variables的动态sql，这样，优化器将缓存查询和执行计划。

declare @sql varchar(500)
DECLARE @ParmDefinition nvarchar(500);

SET @sql='select * from a where 1=1 '
 if @Locationid  is null
set @sql=@sql +' and @LocationId is null'
 else
 set @sql=@sql +' and LocationID= @LocationId'

  EXECUTE sp_executesql @sql, N'@LocationId int',
              @LocationID ;

ALL IF SQL中的Null逻辑

2 个答案: