mysql_errno and mysql_error always reporting something - php

Question

I have a query written as
mysql_query($query,$conn)
or
die(
"A MySQL error has occurred.<br />Your Query: " . $query . "<br /> Error: (" . mysql_errno() . ") " . mysql_error());
echo "You have been entered into our Database!";
This outputs
A MySQL error has occurred.
Your Query: INSERT INTO users (uid, twname, privacy) VALUES (15400743, 'gdhdh', 'accepted')
Error: (0)
so it doesn't list any errors or anything. When I copy/paste that query into the SQL tab of PHPMyAdmin, it runs successfully, and the DB connection isn't throwing anything bad (I know it works because a query works well elsewhere):
function get_db_conn() {
$conn = mysql_connect($GLOBALS['db_ip'], $GLOBALS['db_user'], $GLOBALS['db_pass']);
mysql_select_db($GLOBALS['db_name'], $conn);
return $conn;
}
Any thoughts on what I could fix? I'd really appreciate it.

Answer 1

Error 0 means that no error occurred.
Therefore if the code to output an error is being run when no error occurred you have a logic error in your code surrounding the call to the mysql_query() function.
It's hard to tell from your code what should and shouldn't run under different conditions and where the error may lie.
The following code is logically equivalent to what you are trying to achieve and should work as expected.
This code more clearly separates calling the mysql_query() function from checking the result of calling the function. I have also formatted the code a little to that it displays without any horizontal scrolling, although that's purely optional.
$queryResult = mysql_query($query, $conn);
if ($queryResult === false) {
$errorMessage = "A MySQL error has occurred.<br />"
. "Your Query: ".$query."<br />"
. " Error: (".mysql_errno().") ".mysql_error();
die($errorMessage);
}

Answer 2

I'm not sure if this is exactly what you're looking for, but the argument to the function is called $query, and the variable in your error is $your_query, so the value of $your_query displays in the error, but who knows what is in $query, so if it's NULL, that might cause the error number 0 with no message.