[RESOLVED] PDO-MySQL: concurrent prepared statements?

Havin_it

Hello,

A quick question: Is it possible with PDO-MySQL to prepare and use two (or more) statements at the same time?

TIA =)

Roger_Ramjet

Not sure that I follow what you are asking: "at the same time" ???

Havin_it

Sorry, to be more clear, something like this:

$stmt1 = $db->prepare("UPDATE table1 SET col1 = :a WHERE col2 = :b;");
$stmt1->bindParam(':a',$a);
$stmt1->bindParam(':b',$b);
$stmt2 = $db->prepare("INSERT INTO table1(col1) VALUES(:c);");
$stmt2->bindParam(':c',$c);

while($someCondition) {
    $a = $someValue;
    $b = $otherValue;
    $stmt1->execute();
    if($otherCondition) {
        $c = $yetAnotherValue;
        $stmt2->execute();
    }
}

I tried to build an example like this, but it failed on the bindParam() call for the second statement with "Fatal error: call to member function bindParam() on a non-object."

Roger_Ramjet

Strange behaviour?? Not something I have come across so I've no idea, sorry.

Havin_it

Just done some further diagnosis by trying it on the MySQL cli, and there's no problem in preparing and alternately executing two statements in that context.

Either this is a big gap in the PHP manual, or is just something implicit that I don't get because I'm quite new to the OO approach and conventions. I'll be happy to file a bug on this if that seems the right thing to do, but any further advice would be appreciated.

Roger_Ramjet

My feelings exactly. If pdo could only handle 1 prepared statement at a time then there is nothing in the manual to indicate this. In any case it should throw a pdo exception if that were the case.

Have to tried preparing that second query on its own? See if it some syntax problem we are overlooking.

Also, turn PDO error reporting ON

$this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

in case you are suppressing exception reporting

Havin_it

Right, it looks like I was barking up the wrong tree. In my example above I'd followed the prepare() call with a debug statement:

$stmt = $db->prepare('bla bla') || die("Errors");

(Old practice from old mysql extension)
When I switched to the try/catch syntax, it worked fine. So, to answer my own question: yes, you can use two prepared statements concurrently 😉

Thanks for pointing me in the right direction.