[RESOLVED] Way of comparing two queries without if/esles?

denzlite

Right now here's my code:

		$query1="Select *from table1";
			$data_set=mysql_query($query1);
			if(mysql_num_rows($data_set)==0){
			  $query2="Select *from table2";
			  $data_re_set = mysql_query($query2);
			  if(mysql_num_rows($data_re_set)==0){				
				  //so if there's no info in either of these places
                                 show_form();


		 }

So here's how the previous guy did it - 2 forms get written to 2 different tables and when someone comes to get their form this checks to make sure they haven't already submitted...

Is there a better way to do this?

laserlight

Um, this seems to check if both of the tables are empty. If so, it "goes ahead and does whatever".

denzlite

yes, that's correct.

the user fills out one of two forms - which write to two different tables.

this is trying to determine whether the person has entered info in either of the forms? if both queries return == 0, then show the form to the user...

laserlight

hmm... that is a rather unusual setup. Anyway, one way to do this would be with this query:

SELECT SUM(total) FROM (
    SELECT COUNT(*) AS total FROM table1
    UNION
    SELECT COUNT(*) AS total FROM table2)

Clearly, if the sum of the number of rows from both tables is zero, then they both must be empty.

denzlite

thanks, I new there had to be a better way

laserlight

You're welcome, though note that I am not a database guru so my suggested SQL statement may not be a particularly good one 🙂

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