SQL Select SUM question

[Dave Addey]

Hi Ruslan,

> TIP:
> 
>     SELECT * is not very safe, because if future you change
>     fields in tables your old code can be broken.

I found it was quicker to SELECT * than it was to build a list of the fields
I needed.  I have complete control over my table structure, so this
shouldn't cause a problem in the future.  Thanks for the tip, though!

>> This gives a database error:
>> 
>> ³In the SELECT clause you an use only fields listed in the GROUP BY and
>> aggregate functions.²
> 
> Right. SQL Standard

Okay.

>> Can I do the general ³SELECT Tracks.*², and also the ³SELECT SUM()², as part
>> of the same query?  If so:
> 
> no

So I think I need to do this instead, as a separate query:

SELECT SUM(Tracks.Duration) FROM Tracks, PlaylistTracks WHERE
PlaylistTracks.TrackUniqueIDPtr = Tracks.UniqueID AND
PlaylistTracks.PlaylistUniqueIDPtr = 22731

That seems to work - thanks!

Dave.