On Tue, 3 Jul 2001 09:54, Christian Dechery wrote:
> I have to get some results from a mysql table, and I'm pretty sure that
> I'm not doing it the best way.
>
> its like this... I have a table (a historical one) with these fields:
> date | item_id | item_type_id | qty | value
>
> and there are multiple lines for the pair item/type (as I said it's a
> historical table). I want the row with the last date.
> So if I had:
>
> 2001-29-6 | 34 | 3 | 5 | 15.0
> 2001-30-6 | 34 | 3 | 7 | 13.0
> 2001-1-7 | 34 | 3 | 9 | 12.0
> 2001-2-7 | 34 | 3 | 1 | 3.5
>
> I only want the last one '2001-2-7'. But I can't think of a way of
> doing this without sub-select. So I did this:
>
> <pre>
> $rs1=mysql_query("select max(date) from tablename where item_id=34 and
> item_type_id=3");
> $last_date=mysql_result($rs1,0,0);
>
> $rs2=mysql_query("select qty,value from tablename where
> date='$last_date'"); list($qty,$value) = mysql_fetch_row($rs2);
> </pre>
>
> it works fine... but I don't think it is good... whenever there is
> 'code' between queries to get results I think something could be
> optimized. Any ideas?
Try
$rs1=mysql_query("select max(date) AS latest, * from tablename where
item_id=34 and item_type_id=3");
but consider that you may possibly have multiple entries for the latest
date?
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David Robley Techno-JoaT, Web Maintainer, Mail List Admin, etc
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