php - Calling stored procedure with Out parameter using PDO

Question

I've been using PDO for awhile now and am refactoring a project so that it uses stored procs instead of inline SQL. I am getting an error that I can't explain.I am using PHP version 5.3.5 and MySQL version 5.0.7.

I'm just trying to get a basic stored proc with an output to work. Here is the stored proc:

DELIMITER //  
CREATE PROCEDURE `proc_OUT` (OUT var1 VARCHAR(100))  
BEGIN  
    SET var1 = 'This is a test';  
END //  

Here is the code I am using to call the proc, $db is an instance of PDO:

$stmt = $db->prepare("CALL proc_OUT(?)");
$stmt->bindParam(1, $return_value, PDO::PARAM_STR, 4000); 

    // call the stored procedure
    $stmt->execute();
    echo $returnvalue;

Simple right? However, it results in the following error:

exception 'PDOException' with message 'SQLSTATE[42000]: Syntax error or access violation: 1414 OUT or INOUT argument 1 for routine mydb.proc_OUT is not a variable or NEW pseudo-variable in BEFORE trigger

If I call the proc directly like so:

CALL proc_OUT(@res);
SELECT @res;

it works as expected which leads me to believe that there is a problem with how it is being called with PHP, however I can't seem to find what the issue is. I am following the instructions in the manual but am still getting this error. Could anyone suggest what I could be doing wrong? Any advice would be very much appreciated. Thanks much!

Answer 1

It would seem that there is a bug at work here, best solution I've found is this:

http://www.php.net/manual/en/pdo.prepared-statements.php#101993

From the comment at the link above:

$dbh->query("CALL SomeStoredProcedure($someInParameter1, $someInParameter2, @someOutParameter)"); 
$dbh->query("SELECT @someOutParameter");

// OR, if you want very much to use PDO.Prepare(),
// insert "SELECT @someOutParameter" in your stored procedure and then use:

$stmt = $dbh->prepare("CALL SomeStoredProcedure(?, ?)"); 
$stmt ->execute(array($someInParameter1, $someInParameter2));

See also this: https://stackoverflow.com/a/4502524/815386