How to use of SQLSTATE '45000' MESSAGE_TEXT in PHP? - php

Question

I have a trigger like this:
CREATE TRIGGER prevent_self_votes BEFORE INSERT ON votes
FOR EACH ROW
BEGIN
IF(new.user_id = (SELECT author_id FROM posts WHERE id=new.post_id)) THEN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = "you cannot vote for yourself";
END IF;
END;
Now I want to know, how can I use of that text you cannot vote for yourself in PHP?
Note: I use PDO.

Answer 1

You can do a try...catch and check for the result of statement execution to print error information like this:
Stub
create table votes (user_id int);
delimiter //
create trigger prevent_self_votes before insert on votes
for each row
begin
if (new.user_id = 12) then
signal sqlstate '45000' set message_text = 'You cannot vote for yourself, dude!';
end if;
end //
delimiter ;
PHP script
<?php
$db = new PDO('mysql:host=localhost;dbname=test', 'test', 'test');
$sql = 'insert into votes values (:user_id)';
$statement = $db->prepare($sql);
if ($statement === false) {
echo 'statement is false';
exit();
}
try {
$result = $statement->execute(array(':user_id'=>12));
if ($result === false) {
$error = $statement->errorInfo();
print_r($error);
echo "$error[2] ... is the error reported by trigger\n";
}
else {
print_r($result);
echo 'Inserted', "\n";
}
}
catch (PDOException $e) {
echo $e->getMessage();
}
?>
Result
$ php test.php
Array
(
[0] => 45000
[1] => 1644
[2] => You cannot vote for yourself, dude!
)
You cannot vote for yourself, dude! ... is the error reported by trigger
As you notice here, you could use the output of $statement->errorInfo()[2] to extract information provided by the trigger.
http://php.net/manual/en/pdo.errorinfo.php says that the first item in the array is SQLSTATE ANSI SQL error code, second item is driver specific error code and third item is driver specific error message.

Answer 2

If your query fails, check what caused the failure Look at the definition of PDOStatement::errorInfo.