[RESOLVED] mysql_connect

182x

Hey guys, I was just wondering as shown in the following code as there is a connection parameter used is the 'or die' part of the code still needed and in this case what does it do?

Thanks.

session_start();
include ('db.php');
$link = connect('');
$getvar = "SELECT p from u, result WHERE mr = mn;
$query = mysql_query($getvar, $link) or die("Error in $getvar: " . mysql_error());

laserlight

Just because you are connected to the database server does not mean that the query sent is guaranteed not to fail. As such, you still need to handle a possible error, and that is one (not very graceful) way of doing it.

Basically, it makes use of lazy evaluation for or: if mysql_query() returns a value that evaluates to true, the second part of the expression is not evaluated, hence the die() is not called. If it returns false, then the second part of the expression is evaluated, hence the script terminates immediately with the error message printed.

NogDog

The "or die" will get executed if the mysql_query() returns false (or, actually, any value that evaluates as false when cast to a boolean type). Therefore, the main purpose of the die() will be for it to execute if there is some sort of error in the query that causes MySQL to return an error instead of a query result.

182x

Thanks for the replies. Is the or die aspect of teh code also still required if the db.php included file has it own error handling features?

laserlight

Is the or die aspect of teh code also still required if the db.php included file has it own error handling features?

It is not "required", just that you should handle possible errors instead of blindly going on to use the resource you expect to be returned. If you are using a database API wrapper with its own error handling methods, then perhaps it would be a good idea to use them.

182x

Thanks for clearing that up, sorry for the newbie questions and thanks for your rapid responces. 🙂

bradgrafelman

Don't forget to mark this thread resolved (if it is).