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POis this a candidate for a sql groupby query?
 

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  1. POis this a candidate for a sql groupby query?
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    <p>I have two tables: <strong>TableA</strong> (<code>ID [int, pk], Name [string])</code> and <strong>TableB</strong> <code>(ID [int, pk], TableA_ID [int, fk], Name [string], DateStamp [datetime (dd/mm/yyyy hh:MM:ss)])</code>. There is a one-to-many relationship between TableA and TableB.</p> <p>An inner join on the two tables will give me the following results:</p> <pre> TableA.ID, TableA.Name, TableB.Name, TableB.DateStamp 1, 'File A', 'Version 1', 01/01/2009 15:00:00 1, 'File A', 'Version 2', 05/01/2009 08:15:00 1, 'File A', 'Version 3', 06/01/2009 19:33:00 2, 'File B', 'Version 1', 03/01/2009 09:10:00 2, 'File B', 'Version 2', 20/01/2009 20:00:00 3, 'File C', 'Version 1', 01/01/2009 17:00:00 </pre> <p>What I actually want is the following (each row from TableA and the last matching row from TableB):</p> <pre> TableA.ID, TableA.Name, TableB.Name, TableB.DateStamp 1, 'File A', 'Version 3', 06/01/2009 19:33:00 2, 'File B', 'Version 2', 20/01/2009 20:00:00 3, 'File C', 'Version 1', 01/01/2009 17:00:00 </pre> <p>This is the query that I'm using to achieve this:</p> <pre><code>SELECT ta.ID, ta.Name, tb.Name, tb.DateStamp FROM TableA ta INNER JOIN TableB tb ON ta.ID = tb.TableA_ID WHERE tb.ID IN ( SELECT TOP 1 tb2.ID FROM TableB tb2 WHERE tb2.TableA_ID = ta.ID ORDER BY tb2.DateStamp DESC) </code></pre> <p>That works but my gut feeling is that I'm not doing this in the "best way". It looks like it is a candidate for an aggregation query (i.e. groupby) but I didn't have any luck with that. In the end I always had to use a subquery to get the row I'm after in TableB.</p> <p>Any help much appreciated.</p>
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    1. This table or related slice is empty.
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    1. USTomalak
    1. USNaeem Sarfraz
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      1. POis this a candidate for a sql groupby query?
      1. This table or related slice is empty.
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      1. POis this a candidate for a sql groupby query?
      1. This table or related slice is empty.
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    1. This table or related slice is empty.
 

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