How to detect a rollback in MySQL stored procedure? - php

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();
}
?>