order by something not in table

[aaron_karp]

Ok, so I'm using a SELECT query to grab a bunch of data, and I'm comfortable sorting by field using ORDER BY.

However, I'm populating a table with several values that are calculations based on values of the table. If I want to sort based on these values, how can I do that?

The problem is that the variables that represent the values in the table don't get set until after the SELECT query has run. By that time, it's too late to make calculations and use ORDER BY. How can I remedy this?

Thanks!

[Sxooter]

I'm not entirely sure what you're asking. Is it something like this:

select (field1*field2)/field3 as output order by output

Or is it something like:

select t1.field1, t1.field2 from table1 t1 join table2 t2 on (t1.id=t2.t1id) order by t2.fieldn

[aaron_karp]

I'll give an example to clarify - excuse the poor coding conventions where I omit error reporting:

// Find total amount of donations
$sql = mysql_query("SELECT donation FROM donors");
while ($myarray = mysql_fetch_array($sql)) {
$totaldonation .= $myarray['donation'];
}

$query = "SELECT email, name, donation FROM donors ORDER BY <<percent donated. in other words, donation/$totaldonation>>";

mysql_query($query).......etc.

So, basically, how can I format the ORDER BY so that it sorts based on that calculation, even though the donation for this individual hasn't been calculated yet?

I appreciate the help

[tomhath]

$query = "SELECT email, name, donation FROM donors ORDER BY donation/$totaldonation";

What you use as an example should work. Did you try it?

[aaron_karp]

Oh - well, will ya look at that - I guess it does work. Thanks!

[barand]

Won't a simple order by donation give the same record sequence as order by percent donated?

[aaron_karp]

yeah, it will, but the example I gave was an oversimplified version of a calculation involving a few tables. thanks though.