How do I search for only filled in fields?

[adamgram]

So I'm very new to all this and I'm trying to build a website based on a MySQL database.  I want to make a page that has a bunch of different attributes you can search by.  The way it's set up now if you don't fill out a certain criteria it only turns up entries where that criteria is blank.  I want it to show all of the rows where the other columns match, ignoring the blank one.  Here's what I'm doing now:

 

$result = mysql_query("SELECT * FROM table

WHERE var_1='$var_1'

AND var_2='$var_2'

AND var_3='$var_3'

");

 

$var_1, $var_2, and $var_3 all come from an html form, and if certain fields aren't filled in they're left blank and respond to if... statement where $var_1==''  When I only had 4 of them I made one for each of the 16 possible combinations, but now I want to double that so it's time to figure out a better way.  I've been searching for a couple hours but it seems like I don't know enough about MySQL to know what to look for.  I just copied what I have now from a tutorial.  Anyone one to help point me in the right direction?  Thanks in advance!

 

[fenway]

This is more of a php question -- you need to determine which fields were selected, map those to the table structure, and built your where clause accordingly.

[snk]

if you want to exclude empty fields from database you have to include

 

IS NOT NULL command in your sql query