Question

I have a query with a sub query to get the ranks of each row based on tune_value. If I try to fetch the results I will get a general error from the PDOStatement::fetchAll();. The exectute of the prepare statement doesn’t seem to throw any errors.

I have the following query

SET @rank := 0;
SELECT * FROM 
(
  SELECT *,
         (UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(tunes.creation_date)) as age,
         @rank := @rank + 1 as rank
  FROM tunes
  ORDER BY tune_value DESC
) as t
LEFT JOIN artists ON artists.id = t.artists_id
ORDER BY age

I prepare the statement using the following simplified php code.

   $pdo->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
   $stmt = $pdo->prepare($sql);
   $stmt->execute();
   $stmt->fetchAll(\PDO::FETCH_ASSOC);

Is it impossible to do this subquery with php? I was thinking about maybe making a view of the subquery.

EDIT: To clarify the query works fine in phpmyadmin

Answer 1

PDO doesn’t support multiple queries in one call.
(Means PDO supports subqueries all right, it’s just doesn’t support multiple queries separated by a semicolon)
You have to call them one by one.
And to get errors from PDO, set this attribute

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

EDIT: This means the SET @rank := 0; is a separate query and should be queried in a separate call