Thanks for the answer, didn't think of asking this in a MySQL forum,
sorry.
Dan
On Sun, 2008-01-13 at 20:28 +0100, Jochem Maas wrote:
> Danny Brow schreef:
> > Just wondering if anyone could tell me how reliable the DESC order
> > option is going to be when I am parsing thousands of records where they
> > are multiple ChartNo's for the same clientNo. Or is there a better way
> > to grab the most recent ChartNo.
>
> this is a mysql question not a php question, please try to ask questions
> in the appropriate forum.
>
> the reliability of 'ORDER BY' is not tied to the ammount of
> records returned.
>
> given that you only want the 'most recent'
> (by which I assume you mean the 'highest value') ChartNo for
> a given clientNo you should be performing a query that returns a
> single row of data.
>
> also you shouldn't be quoting values pertaining to numeric fields
> (I assume clientNo is an integer)
>
> 1. assuming ChartNo is numeric:
>
> SELECT MAX(ChartNo) as chartno FROM eChart WHERE clientNo=2
>
> 2. assuming ChartNo is a varchar (or similar):
>
> SELECT ChartNo FROM eChart WHERE clientNo=2 ORDER BY ChartNo DESC LIMIT 0,1
>
> >
> > $link = mysql_connect('localhost', 'myuser', 'mypassword') or die('Could
> > not connect: ' . mysql());
> >
> > mysql_select_db('mydatabase') or die('Could not select database');
> >
> > $query = 'SELECT * FROM eChart WHERE clientNo = "2" ORDER BY ChartNo
> > DESC';
> >
> > $result = mysql_query($query) or die('Query failed: ' . mysql_error());
> >
> > $line = mysql_fetch_array($result, MYSQL_ASSOC);
> >
> >
> > // Just for testing....
> > print mysql_num_rows($result);
> >
> >
> >
> > Thanks,
> > Dan
> >
> >
> >
> >
>
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