How could I perform queries using data from a previous query?
I want this because i have a category table and a subcategory table
and for every category it performs a query on the subcategory table.

Do you know what I mean? If not I can edit the topic for clarity.

can you post the tables basic structure and what exacly you want to do ?

first query:

PHP Code:

$_SESSION['qry1'] = mysql_fetch_array(mysql_query("SELECT * FROM users WHERE Username = 'Bob'")); 


The session variable should have all the info about bob that you could use for a second query, like $_SESSION['qry1']['firstName']. But if the second query or even the first query is going to be returning multiple rows of data, you would have to do:

PHP Code:

 while($row = mysql_fetch_assoc($qry))
{ 
second query
} 


Hopefully this helps, but if you have any questions, just ask.

Sorry never realised i forgot to give the code.

PHP Code:

while($post = mysql_fetch_array(mysql_query("select * from posts where topic='$id'")))
{
    echo($post['body']);
    echo($post['userid']);
    echo($post['date']);
    echo("<br/>");
} 


I think that's for the other thread, no?

Sorry, about that, guess i posted the wrong code here. I'll need to try your ideas out, and the one that got it right, well I'll give you some talkupation