php - PDO error: SQLSTATE[HY000]: General error: 2031

Question

I'm getting this annoying error and although I have an idea of why I'm getting it, I can't for the life of me find a solution to it.

if ($limit) {
   $sth->bindValue(':page', $page - 1, PDO::PARAM_INT);
   $sth->bindValue(':entries_per_page', $page * $entries_per_page, PDO::PARAM_INT);
}

$sth->execute($criteria);

Query contains placeholders (:placeholder). But to add those LIMIT placeholders, I need to use the manual method (bindValue) because otherwise the engine will turn them into strings.

I'm not getting the Invalid number of parameters error, so all placeholders have been bound correctly (I assume).

Query:

SELECT `articles`.*, `regional_municipalities`.`name` AS `regional_municipality_name`, 
       `_atc_codes`.`code` AS `atc_code`, `_atc_codes`.`name` AS `substance`
FROM `articles`
LEFT JOIN `_atc_codes`
ON (`_atc_codes`.`id` = `articles`.`atc_code`)
JOIN `regional_municipalities`
ON (`regional_municipalities`.`id` = `articles`.`regional_municipality`)
WHERE TRUE AND `articles`.`strength` = :strength
GROUP BY `articles`.`id`
ORDER BY `articles`.`id`
LIMIT :page, :entries_per_page

All placeholder values reside in $criteria, except for the last two LIMIT, which I manually bind with bindValue().

Answer 1

This same error 2031 can be issued when one bind two values with the same parameter name, like in:

• $sth->bindValue(':colour', 'blue');
• $sth->bindValue(':colour', 'red');

..so, beware.