How to execute query in codeigniter

SELECT CONCAT(
    'SELECT `ci`.item_id,`ci`.itemName,`ci`.order_date', GROUP_CONCAT('
     ,    `t_', REPLACE(Outlet_name, '`', '``'), '`.QtyRequested
         AS `', REPLACE(Outlet_name, '`', '``'), '`'
     SEPARATOR ''),
 ' FROM `chef_comp_items` as ci ', GROUP_CONCAT('
     LEFT JOIN `chef_comp_items`  AS `t_', REPLACE(Outlet_name, '`', '``'), '`
            ON `ci`.item_id = `t_', REPLACE(Outlet_name, '`', '``'), '`.item_id
           AND `t_', REPLACE(Outlet_name, '`', '``'), '`.Outlet_name = ', QUOTE(Outlet_name)
     SEPARATOR ''),
 ' GROUP BY `ci`.item_id'
) INTO @qry FROM (SELECT DISTINCT Outlet_name FROM `chef_comp_items`) t;

PREPARE stmt FROM @qry;
EXECUTE stmt;