having nested mysql_fetch_assoc statements

sarmenhb · 06-12-2008, 07:49 PM

is it possible to have something like this?
because in the nested query i am getting an error

the error says:

<b>Warning</b>: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in

this is the sql statement: select label from tbl_group order by id

Code:

$sql1 = "select * from table";
$sql2 = "select * from anothertable";

while($row1 = mysql_fetch_assoc($sql1)) { 

     // do something 

         while($row = mysql_fetch_assoc($sql2)) {


      // do something else

}
}

thnx

buggabill · 06-12-2008, 07:56 PM

You need to run mysql_query on those sql strings.

Like this:

php Code:

$sql1 = "select * from table";
$sql2 = "select * from anothertable";

$result1 = mysql_query($sql1);
$result2 = mysql_query($sql2);

while($row1 = mysql_fetch_assoc($result1)) { 

     // do something 

         while($row = mysql_fetch_assoc($result2)) {


      // do something else

}
}

mysql_fetch_assoc works on valid mysql result sets and not on strings that are intended to be queries.

xenon · 06-12-2008, 08:25 PM

Plus, if you need to nest mysql_fetch_assoc functions, then you'll also need separate database connections ;)

dschreck · 06-13-2008, 05:06 AM

Quote:

Originally Posted by xenon

Plus, if you need to nest mysql_fetch_assoc functions, then you'll also need separate database connections ;)

He won't need to declare another mysql_connect(). MySQL will handle this by itself. While true, it does create another thread, it does not require to mysql_connect() again. Nesting does not truly have any adverse effects.
While it may be recommended that he does a JOIN instead of one query and another, or at least attempt a sub query, I wouldn't say using nested mysql_fetch_assoc() need any type of warning.

Just my 2 cents though :P

Jim · 06-13-2008, 06:35 AM

It's the same database so multiple connections would be useless. When providing a different source (via a query) PHP will automagically differiate them. (is "differiate" english?

)

I think a JOIN in the SQL would be a bit to much for this person at the moment. :) Not to diss him, but he's a beginner so this is enough already :)

dschreck · 06-13-2008, 04:12 PM

Quote:

Originally Posted by Jim

... (via a query) PHP will automagically differiate them. (is "differiate" english?

)
...

I'll accept differiate, but automagically is just straight out silly ;)