Is there a way to remove middel join to better performance ? I want to get cardno field after middle join ,

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SQL

SELECT Top 1  details.PersonnelBaseID FROM dbo.tkp_PersonnelDetails INNER JOIN
(
	SELECT 
		personnelDetails.EffectiveDate,personnelDetails.PersonnelBaseID,CardNo 
	FROM 
		dbo.tkp_PersonnelDetails AS personnelDetails 
	INNER JOIN
	(
		SELECT  
				Max(EffectiveDate) AS EffectiveDate,details.PersonnelBaseID
		FROM            
			dbo.tkp_PersonnelDetails AS details INNER JOIN
			prs_Personnel personnel ON personnel.ID = details.PersonnelBaseID AND 
			Personnel.Active = 1 AND 
			Personnel.Deleted = 0 AND
			details.Deleted = 0 AND 
			details.EffectiveDate <= @Time
		GROUP BY PersonnelBaseID
	)result ON result.PersonnelBaseID = personnelDetails.PersonnelBaseId AND result.EffectiveDate = personnelDetails.EffectiveDate
)details ON tkp_PersonnelDetails.PersonnelBaseID = details.PersonnelBaseId AND tkp_PersonnelDetails.cardNo = @CardNo
ORDER BY tkp_PersonnelDetails.Effectivedate DESC

What I have tried:

is there a way to remove middel join to better performance ? i want to get CardNo Field After join

Posted 23-Oct-16 5:21am

mhd.sbt

Updated 23-Oct-16 5:22am

v2

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Wendelius · Answer 1 · 2016-10-23T05:32:00

Taken that the logic should not change, you can make different kinds of modifications of the statement but you cannot completely remove the join since that would affect the results.

For example one variation could be

SQL

WITH r1 (
   SELECT  Max(EffectiveDate) AS EffectiveDate,details.PersonnelBaseID
   FROM dbo.tkp_PersonnelDetails AS details INNER JOIN
	prs_Personnel personnel ON personnel.ID = details.PersonnelBaseID AND 
	Personnel.Active = 1 AND 
	Personnel.Deleted = 0 AND
	details.Deleted = 0 AND 
	details.EffectiveDate <= @Time
   GROUP BY PersonnelBaseID
)
SELECT Top 1  details.PersonnelBaseID FROM dbo.tkp_PersonnelDetails INNER JOIN
(
	SELECT personnelDetails.EffectiveDate,personnelDetails.PersonnelBaseID,CardNo 
	FROM dbo.tkp_PersonnelDetails AS personnelDetails 
	INNER JOIN r1 ON r1.PersonnelBaseID = personnelDetails.PersonnelBaseId 
                      AND r1.EffectiveDate = personnelDetails.EffectiveDate
) details ON tkp_PersonnelDetails.PersonnelBaseID = details.PersonnelBaseId 
          AND tkp_PersonnelDetails.cardNo = @CardNo
ORDER BY tkp_PersonnelDetails.Effectivedate DESC

Another variation could be to use an EXISTS structure.

But what comes to the performance, the first thing to do is to check if you have all necessary indexes in place. For example something like:
- Table prs_Personnel columns Id, Active, Deleted
- Table tkp_PersonnelDetails columns PersonnelBaseID, Deleted, EffectiveDate