Quick Check if data exists

[Samg]

I have a form submitting to a database. Before saving the information, I want to run various checks on the data.

How can I check if the data exists in the Database?

This is what I figured out so far, (not complete)...

// Verify if the submitted key exists in table 'fromto' column 'fromto_id'
function VerifyDataFromTo($str)
{
	 $query = "SELECT fromto_id FROM fromto WHERE fromto_id = $str LIMIT 1";
	 $query = stripslashes($query);
	 $result = mysql_query($query) or die("Ouch...");
	 if (!in_array($str,$result)) {die ("Hey Kiddo, Somethin's wrong");}
}

VerifyDataFromTo($_POST['fromto']);

How can I return a nice error message (instead of the "die" message)?

Thanks for the help...

[devinemke]

function VerifyDataFromTo($str)
{
     $sql = "SELECT COUNT(*) FROM fromto WHERE fromto_id = '$str'";
		 $result = mysql_query($sql) or exit(mysql_error());
		 if (mysql_result($result, 0))
		 {
			 echo 'the fromto_id ' . $str . ' is already in the fromto table';
			 exit();
		 }
}

VerifyDataFromTo($_POST['fromto']);