Complex sql statement in Laravel 3

Question

This is my code at the moment

    $piv0 = "SET @pivot_query = NULL;";
    $piv1 = "SELECT GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(custom_field = \"\"',custom_field,\"\"', cf_values, NULL)) AS ',custom_field)) INTO @pivot_query FROM custom_fields_values; ";

    $piv2 = "SET @pivot = CONCAT('SELECT subscriber_id, ', @pivot_query, ' FROM custom_fields_values GROUP BY subscriber_id');";

    $piv3 = "SET @sql = CONCAT('SELECT * FROM user_data_3 LEFT JOIN (',@pivot,') piv ON user_data_5.aw_id = piv.subscriber_id');";
    $piv4 = "PREPARE stmt FROM @sql; ";
    $piv5 = "EXECUTE stmt;";
    $piv6 = "DEALLOCATE PREPARE stmt;";

    $db = DB::connection()->pdo;
    $db->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);

    $query = $db->prepare($piv0);
    $query->execute();

    $query = $db->prepare($piv1);
    $query->execute();

    $query = $db->prepare($piv2);
    $query->execute();

    $query = $db->prepare($piv3);
    $query->execute();

    $query = $db->prepare($piv4);
    $query->execute();

    $query = $db->prepare($piv5);
    $query->execute();

    $query = $db->prepare($piv6);
    $query->execute();

    $result = $query->fetchAll();

However, I am getting the error:

General error: 2014 Cannot execute queries while other unbuffered queries are active.  Consider using PDOStatement::fetchAll().  Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.

I looked at some other SO questions and it was mentioned that $query->fetchAll() and/or $query->closeCursor() should help, but they didn't help me here.

I am getting the error on $query = $db->prepare($piv4);

What else should I try?

Answer 1

I managed to come up with a workaround:

$middleQueryRes = DB::query("SELECT GROUP_CONCAT(DISTINCT CONCAT('MAX(IF(custom_field =''', custom_field,''', cf_values, NULL)) AS ',custom_field)) FROM custom_fields_values;");
foreach ($middleQueryRes[0] as $value) {
   $middleQueryRes = $value
   break;
 }

$middleQuery2 = "SELECT subscriber_id, $middleQueryRes FROM custom_fields_values GROUP BY subscriber_id";

$finalRes = DB::query("SELECT * FROM user_data_3 LEFT JOIN ($middleQuery2) piv ON user_data_5.aw_id = piv.subscriber_id");