How to detect a rollback in MySQL stored procedure?

Question

I'm trying to figure out a way to detect an occurrence of rollback in a MySQL stored procedure so I could handle the situation accordingly from a PHP script, but so far I can not find any solution.

My stored procedure looks like this:

     delimiter |
      create procedure multi_inserts(
      IN var1 int(11),
           .
           .
           .
      IN string1 text
      )
      BEGIN

      declare exit handler for sqlexception rollback;
      declare exit handler for sqlwarning rollback;

      START TRANSACTION;
      insert into table1(a,b,c,d) values(var1,var2,var3,var4);
      insert into table2(e,f,g) values(var5,var6,string1);
      COMMIT;

      END
      delimiter ;

I did a rollback test on this procedure and it did rollback but I got no false. I want my stored procedure to throw some kind of error message if the transaction failed, so I could handle it like this:

    $result = mysql_query($procedure); 
    if(!$result) 
    {
      //rollback occured do something   
    }

Is there a way to detect rollback in MySQL? Am I missing something? Any reply will be appreciated. Thanks for reading.

---

Thanks to your advices I fixed this problem. Here's what I did:

Stored Procedure

     delimiter |
      create procedure multi_inserts(
      IN var1 int(11),
           .
           .
           .
      IN string1 text
      )
      BEGIN

      declare exit handler for sqlexception sqlwarning
      BEGIN
      rollback;
      select -1;
      END;

      START TRANSACTION;
      insert into table1(a,b,c,d) values(var1,var2,var3,var4);
      insert into table2(e,f,g) values(var5,var6,string1);
      COMMIT;

      END
      delimiter ;

If I use out variable instead of select -1, it gives me this error:

OUT or INOUT argument is not a variable or NEW pseudo-variable in BEFORE trigger

I don't know what did I wrong, but I couldn't fix this problem.

PHP script

$result=mysqli_query($con,$procedure);
if(is_object($result))
{
//rollback happened do something!
}

If the SP is successful it throws true.

Answer 1

You can add an output param and then set it to the value you want in your exit handlers.

Here's an example using your proc:

delimiter $$
  create procedure multi_inserts(
  IN var1 int(11),
       .
       .
       .
  IN string1 text,
  OUT p_return_code tinyint unsigned
  )
  BEGIN

  DECLARE exit handler for sqlexception
  BEGIN
    -- ERROR
    set p_return_code = 1;
    rollback;
  END;

  DECLARE exit handler for sqlwarning
  BEGIN
    -- WARNING
    set p_return_code = 2;
    rollback;
  END;

  START TRANSACTION;
  insert into table1(a,b,c,d) values(var1,var2,var3,var4);
  insert into table2(e,f,g) values(var5,var6,string1);
  COMMIT;

  -- SUCCESS
  set p_return_code = 0;

  END $$
  delimiter ;

Answer 2

You would usually do this PHP-side if you wanted to catch errors. Read http://php.net/manual/en/pdo.transactions.php for more information.

Answer 3

Hey do one thing, use OUTPUT variable and return 1 or 0 as result form SP and do what ever you want on this flag.

Answer 4

<?php
try {
    $user='root';
    $pass='';
  $dbh = new PDO('mysql:host=localhost;dbname=dbname', $user, $pass, 
      array(PDO::ATTR_PERSISTENT => true));
  echo "Connected\n";
} catch (Exception $e) {
  die("Unable to connect: " . $e->getMessage());
}

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

  $dbh->beginTransaction();
  $dbh->exec("insert into staff (id, first, last) values (23, 'Joe', 'Bloggs')");
  $dbh->exec("insert into salarychange (id, amount, changedate) 
      values (23, 50000, NOW())");
  $dbh->commit();

} 
catch (Exception $e) {
  $dbh->rollBack();
  echo "Failed: " . $e->getMessage();
}
?>