Question

I am trying to write a query with some fancy joins. I know this can be done, but I am not remembering how to do it.

Here is my query as it is now:

SELECT  parentLink.SourceWorkItemID, parentLink.TargetWorkItemID,
            childLink.SourceWorkItemID, childLink.TargetWorkItemID, 
            childLink.WorkItemLinkTypeSK--,childLinkType.LinkName
FROM    dbo.FactWorkItemLinkHistory parentLink
        JOIN dbo.DimWorkItemLinkType parentLinkType (NOLOCK)
            ON parentLink.WorkItemLinkTypeSK = parentLinkType.WorkItemLinkTypeSK
        LEFT JOIN dbo.FactWorkItemLinkHistory childLink (NOLOCK)
            ON parentLink.TargetWorkItemID = childLink.SourceWorkItemID
            AND childLink.RemovedByPersonSK IS NULL
            AND childLink.WorkItemLinkTypeSK IN 
               (SELECT  sublink.WorkItemLinkTypeSK
                FROM    dbo.DimWorkItemLinkType sublink
                WHERE   sublink.LinkName = 'Child'
               )
        --LEFT JOIN dbo.DimWorkItemLinkType childLinkType (NOLOCK)
        --  ON childLink.WorkItemLinkTypeSK = childLinkType.WorkItemLinkTypeSK  
        --  AND childLinkType.LinkName = 'Child'            
WHERE   parentLink.SourceWorkItemID = 1917
        AND parentLink.RemovedByPersonSK IS NULL        
        AND parentLinkType.LinkName = 'Releases Story'

I have tried to get this to run without the select clause in the from part of my query, but it keeps eluding me.

The result I am looking for is something this:

1917    1915    1915    1916    2
1917    1913    1913    1914    2
1917    1913    1913    4349    2
1917    1921    1921    1922    2
1917    1918    NULL    NULL    NULL
1917    1920    NULL    NULL    NULL

I get that result using the select in the from clause, but I would rather not use a select there if I can avoid it.

I tried making these changes:

1. Uncomment the last join (and childLinkType.LinkName in the main select clause)
2. Remove the unwanted select clause (the line above the last join).

When I do I get this:

1917    1915    1915    1916    2   Child
1917    1915    1915    1917    20  NULL
1917    1915    1915    1919    7   NULL
1917    1915    1915    1911    4   NULL
1917    1913    1913    1914    2   Child
1917    1913    1913    1917    20  NULL
1917    1913    1913    1911    4   NULL
1917    1913    1913    4349    2   Child
1917    1921    1921    1922    2   Child
1917    1921    1921    1917    20  NULL
1917    1918    1918    1919    7   NULL
1917    1918    1918    1912    4   NULL
1917    1918    1918    1917    20  NULL
1917    1920    1920    1911    4   NULL
1917    1920    1920    1917    20  NULL

That is too many rows. And the I don’t want nulls matching on the DimWorkItemLinkType table. So I make the last join an inner join. Then I get this:

1917    1915    1915    1916    2   Child
1917    1913    1913    1914    2   Child
1917    1913    1913    4349    2   Child
1917    1921    1921    1922    2   Child

That has removed the items that don’t have a “child” (1918 and 1920 from the first data set). I still need them in my results.

Any ideas how I can remove the select (in the from clause) and still get this to give me the first set of results?

NOTE: I am running this against the TFS_Warehouse database on TFS 2010 server (using the tables that are approved for reporting purposes).

Answer 1

Well, I won’t pretend I really understand your question — as others have said, it might be worth trying to break it down and simplify it — and I don’t have a TFS_Warehouse, but I’m going to take a chance and guess that you’re looking for a structure something like this (untested, obviously):

SELECT  parentLink.SourceWorkItemID, parentLink.TargetWorkItemID,
            childLink.SourceWorkItemID, childLink.TargetWorkItemID, 
            childLink.WorkItemLinkTypeSK--,childLinkType.LinkName
FROM    dbo.FactWorkItemLinkHistory parentLink
        JOIN dbo.DimWorkItemLinkType parentLinkType (NOLOCK)
            ON parentLink.WorkItemLinkTypeSK = parentLinkType.WorkItemLinkTypeSK
        LEFT JOIN 
          (dbo.FactWorkItemLinkHistory childLink (NOLOCK)
            INNER JOIN dbo.DimWorkItemLinkType childLinkType (NOLOCK)
              ON childLink.WorkItemLinkTypeSK = childLinkType.WorkItemLinkTypeSK  
              AND childLinkType.LinkName = 'Child')
          ON parentLink.TargetWorkItemID = childLink.SourceWorkItemID
          AND childLink.RemovedByPersonSK IS NULL
WHERE   parentLink.SourceWorkItemID = 1917
        AND parentLink.RemovedByPersonSK IS NULL        
        AND parentLinkType.LinkName = 'Releases Story'