Alternate to this(joins)

Question

SELECT
ISNULL(LastMember.DimMemberId, -1) AS PrevMemberId
,ISNULL(Member.DimMemberId, -1) AS DimMemberId
,ISNULL(LASTMembership.DimMembershipId, -1) AS PrevMembershipId
,ISNULL(CurrentMembership.DimMembershipId, -1) AS DimMembershipId
,ISNULL(MemberActivity.MemberActivityId, -1) AS MemberActivityId
,ISNULL(MembershipActivity.MembershipActivityId, -1) AS MembershipActivityId
,CAST(CONVERT(CHAR(8), CurrentMembership.Meta_DateRowEff, 112) AS INT) AS MemberActivityDateId
,-1 as DimEmployeeId
,member.MembershipNum
,member.MemberNum
FROM
(SELECT DimMembershipId, MembershipNum ,ServiceLevelId, Meta_DateRowEff
FROM DW.Dim_Membership
WHERE Meta_IsCurrent = 'Y' AND ServiceLevelId > -1
AND Meta_DateRowEff > GETDATE()-30) AS CurrentMembership
INNER JOIN
(SELECT SL.DimMembershipId,SL.MembershipNum, SL.ServiceLevelId
FROM
(SELECT DimMembershipId,MembershipNum ,ServiceLevelId, Meta_DateRowExp
FROM DW.Dim_Membership
WHERE Meta_IsCurrent = 'N' AND ServiceLevelId > -1) AS SL
LEFT OUTER JOIN
(SELECT DimMembershipId,MembershipNum, MAX(Meta_DateRowExp) AS MAXMeta_DateRowExp
FROM DW.Dim_Membership
WHERE Meta_IsCurrent = 'N' AND ServiceLevelId > -1
GROUP BY MembershipNum,DimMembershipId) AS MD
ON MD.MembershipNum = SL.MembershipNum AND MD.MAXMeta_DateRowExp = SL.Meta_DateRowExp
WHERE MD.MAXMeta_DateRowExp IS NOT NULL) AS LastMembership
ON CurrentMembership.MembershipNum = LastMembership.MembershipNum
AND CurrentMembership.ServiceLevelId <> LastMembership.ServiceLevelId
LEFT OUTER JOIN
(SELECT DimMemberId, MembershipNum, MemberNum ,ServiceLevelId
FROM DW.Dim_Member
WHERE Meta_IsCurrent = 'Y' AND ServiceLevelId > -1
AND Meta_DateRowEff > GETDATE()-30) AS Member
ON Member.MembershipNum = CurrentMembership.MembershipNum
---- when i join this part of code, my query is bringing more results it is running for ever and throwing me out of memory execption error.
--can you please tell me the alternative way for this code
INNER JOIN
(SELECT ST.DimMemberId,ST.MembershipNum,ST.MemberNum, ST.ServiceLevelId
FROM
(SELECT DimMemberId,MembershipNum,MemberNum ,ServiceLevelId, Meta_DateRowExp
FROM DW.Dim_Member
WHERE Meta_IsCurrent = 'N' AND ServiceLevelId > -1) AS ST
LEFT OUTER JOIN
(SELECT DimMemberId,MembershipNum,MemberNum, MAX(Meta_DateRowExp) AS MAXMeta_DateRowExp
FROM DW.Dim_Member
WHERE Meta_IsCurrent = 'N' AND ServiceLevelId > -1
GROUP BY MemberNum,MembershipNum,DimMemberId) AS MD
ON MD.MembershipNum = ST.MembershipNum AND MD.MAXMeta_DateRowExp = ST.Meta_DateRowExp
WHERE MD.MAXMeta_DateRowExp IS NOT NULL) AS LastMember
ON CurrentMembership.MembershipNum = LastMember.MembershipNum
AND Member.ServiceLevelId <> LastMember.ServiceLevelId
CROSS JOIN
(SELECT TOP 1 DimActivityId as MemberActivityId FROM
(SELECT DimActivityId, 1 AS ORD
FROM DW.Dim_Activity
WHERE ActivityClass = 'Member'
AND ActivityType = 'Serv Lvl Change'
AND ActivitySubType = 'Serv Lvl Change'
AND Meta_IsCurrent = 'Y'
UNION ALL
SELECT -1 AS DimActivityId, 2 AS ORD) T
ORDER BY ORD) AS MemberActivity
CROSS JOIN
(SELECT TOP 1 DimActivityId as MembershipActivityId FROM
(SELECT DimActivityId, 1 AS ORD
FROM DW.Dim_Activity
WHERE ActivityClass = 'Membership'
AND ActivityType = 'Serv Lvl Change'
AND ActivitySubType = 'Serv Lvl Change'
AND Meta_IsCurrent = 'Y'
UNION ALL
SELECT -1 AS DimActivityId, 2 AS ORD) T
ORDER BY ORD) AS MembershipActivity
CREATE TABLE [DW].[Dim_Membership](
[DimMembershipId] [bigint] IDENTITY(1,1) NOT NULL,
[MembershipNum] [int] NOT NULL,
[ServiceLevelId] [int] NOT NULL,
[Meta_IsCurrent] [char](1) NOT NULL,
[Meta_DateRowEff] [datetime] NOT NULL,
CONSTRAINT [PK_Dim_Membership] PRIMARY KEY CLUSTERED
[DimMembershipId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [DW]
) ON [DW]
CREATE TABLE [DW].[Dim_Member](
[DimMemberId] [bigint] IDENTITY(1,1) NOT NULL,
[MembershipNum] [int] NOT NULL,
[MemberNum] [tinyint] NOT NULL,
[ServiceLevelId] [int] NOT NULL,
[Meta_IsCurrent] [char](1) NOT NULL,
[Meta_DateRowEff] [datetime] NULL,
CONSTRAINT [PK_Dim_Member] PRIMARY KEY CLUSTERED
[DimMemberId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [DW]
) ON [DW]
CREATE TABLE [DW].[Dim_Activity](
[DimActivityId] [int] IDENTITY(1,1) NOT NULL,
[ActivityClass] [varchar](50) NOT NULL,
[ActivityType] [varchar](50) NOT NULL,
[ActivitySubType] [varchar](50) NULL,
[Meta_IsCurrent] [char](1) NOT NULL,
CONSTRAINT [PK_Dim_MemberActivity] PRIMARY KEY CLUSTERED
[DimActivityId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [DW]
) ON [DW]
I inserted the code to create tables. I inserted the code in the code block.
Member table is very very huge table. joining member with itself is making this query slow, can you please suggest the other way.
---- when i join below commented part of code, my query is bringing more results it is running for ever and throwing me out of memory execption error.
--can you please tell me the alternative way for code

Answer 1

When this happens, that is, when you get a row explosion that eventually causes SSMS to choke, the cause is usually that you have incomplete join conditions.
I don't know your tables. Well, you posted the CREATE TABLE statements, but all they have is IDENTITY column of for PK, so I don't know rest of the columns. However, this looks suspect:
 ON CurrentMembership.MembershipNum = LastMembership.MembershipNum
AND CurrentMembership.ServiceLevelId <> LastMembership.ServiceLevelId
If there are 10 rows for the same MembershipNum with 10 different service level ids, this condition will produce 90 rows. That is 10x10 - the 10 where the service level IDs are the same. And then you add a second condition on the same pattern. We now have
900 rows for the same MembershipNum.
But how you should write your query? No, I don't know, because I don't know what you are looking for.
Erland Sommarskog, SQL Server MVP, [email protected]