conditional query?

Hello,

I'm interested in running a query, but only if an earlier query pulls a result.

1st query:

$query= mysql_num_rows(mysql_query("SELECT * FROM Table1 WHERE Column1='$var1'"));

if($check="1")

{ ?>

<br>

<font size="2" face="Arial, Helvetica, sans-serif">The Serial <i><b><?php echo "$varSerial"; ?></b></i>

is Valid. Checking eligibility</font>

<?php }

else          <<<---HERE IS WHAT I NEED HELP WITH

{ ?>

<br>

What can I put here so that if $check="0", (serial invalid) the next query is Not Run.

Is there something like an "else end(serial invalid- redirecting to purchase page)"

eg. $query2= mysql_num_rows(mysql_query("SELECT * FROM Table1 WHERE Column2='$var1'"));

etcetc..

Any input is much appreciated.  I'm a big time beginner.

When posting code, enclose it within the forum's

 . . . 

BBCode tags.

What is it doing that it should not be doing, or not doing that it should be doing right now? IOW, how is it currently not working?