Using pdo in php with stored procedure

Question

I have a simple stored procedure in MySQL database:

DELIMITER $$
CREATE DEFINER=`vidhu`@`%` PROCEDURE `test`(var_datain TEXT)
BEGIN
    SELECT var_datain;
END

When calling this procedure in mysql-workbench it returns the data I put in:

Now when I call it from PHP using pdo I get an error:

Fatal error: Cannot pass parameter 2 by reference in C:/apache......(3rd line)

Here is my php code:

$db = new PDO(DSN, DBUSER, DBPASS);
$stmt = $db->prepare("CALL test(?)");
$stmt->bindParam(1, 'hai!', PDO::PARAM_STR);
$rs = $stmt->execute();
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
echo $result[0];

Answer 1

You need to use bindValue instead of bindParam.

When you use bindParam, it binds the variable provided to the parameter, not the value of the variable.

So, if you do:

$x = 5;
$stmt->bindParam(1, $x, PDO::PARAM_INT);
$x = 6;
$stmt->execute(); //executes with 6 instead of 5

It's actually executed with 6 rather than 5. To do this, the method must have a reference to the variable. You cannot have a reference to a literal, so this means that bindParam cannot be used with literals (or anything you can't have a reference to).

$x = 5;
$stmt->bindValue(1, $x, PDO::PARAM_INT);
$x = 6;
$stmt->execute(); //executes with 5 instead of 6

Then:

$stmt->bindParam(1, 1, PDO::PARAM_INT); 
//invalid because there's no way to pass a literal 1 by reference
$stmt->bindValue(1, 1, PDO::PARAM_INT);
//valid

Answer 2

The bindParam function accepts only values variables, That's why parameter two hai which is not a variable cannot be passed. So it is not necessary the bindValue, but using the bindParam correctly. Example: when using bindParam: From your snippet.

$a = "hai";
$db = new PDO(DSN, DBUSER, DBPASS);
$stmt = $db->prepare("CALL test(?)");
$stmt->bindParam(s, $a, PDO::PARAM_STR);
$rs = $stmt->execute();
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
echo $result[0];

This Should solve your problem and not the answer above.

Answer 3

The following code works for calling without prepare statement!

$query="CALL store_procedure_name(@a)";
$conn->query($query);

$query="SELECT @a as outvar;";
$result = $conn->query($query);
foreach ($result as $x)
{
    $res=$x['outvar'];
}

echo $res;