You need to perform an 'outer join' on your ScreenAttr table. The exact
syntax for this kind of join seems to fluctuate wildly, depending on your
database engine -- look it up :-)
Cheers,
Kerry S
----- Original Message -----
From: Mark Derricutt <[EMAIL PROTECTED]>
To: Multiple recipients of list delphi <[EMAIL PROTECTED]>
Sent: Thursday, 1 July 1999 14:07
Subject: [DUG]: SQL Joins...
> A question on joins which I'm again lost on :P
>
> I have a query that returns x amount of rows (query 1 below). The problem
> I have is that CalcMethod defines several Attribute/Method pairs for an
> Object, some of which may, and may not appear in the ScreenAttr table.
>
> As it stands, the query only returns the records that appear in both
> ScreenAttr -and- CalcMethod, however what I -really- want is all
> Attribute/Methods from CalcMethod, and those that don't appear in
> ScreenAttr to have null fields for X and Y, and those that do, to have
> their values.
>
> I think I need to use a union, or some form of join, but I'm not sure.
> (This is probably really badly explain so I hope someone understands
this).
>
> Mark
>
>
> Query 1:
>
> SELECT DISTINCT
> D.Object, D.CalcTable, D1.X, D1.Y, d3.Attribute, d3.Method
> FROM
> Objects D, ScreenAttr D1, CalcMethod d3
> WHERE
> (d.Object = d3.Object) AND
> (d.Object = :Object) AND
> (d.Object = d1.Object) AND
> (d1.Attribute = d3.Attribute)
> ORDER BY
> D.Object, d3.Attribute, d3.Method
>
>
> --
> Mark Derricutt
>
> --------------------------------------------------------------------------
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> New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
> Website: http://www.delphi.org.nz
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