Illegal mix of collations (utf8mb4_unicode_ci,EXPLICIT) and (utf8mb3_unicode_ci,EXPLICIT) for operation 'ifnull' SQL=SELECT `u`.*,`pr`.*,`l`.`product_name`,`rv`.`vote`, IFNULL(`u`.`name` COLLATE utf8mb4_unicode_ci, `pr`.`customer` COLLATE utf8_unicode_ci) AS customer FROM `#__virtuemart_rating_reviews` AS `pr` INNER JOIN `#__virtuemart_products_mk_mk` AS `l` ON `l`.`virtuemart_product_id` = `pr`.`virtuemart_product_id` LEFT JOIN `#__virtuemart_rating_votes` AS `rv` on (`pr`.`virtuemart_rating_vote_id` IS NOT NULL AND `rv`.`virtuemart_rating_vote_id`=`pr`.`virtuemart_rating_vote_id` ) XOR (`pr`.`virtuemart_rating_vote_id` IS NULL AND (`rv`.`virtuemart_product_id`=`pr`.`virtuemart_product_id` and `rv`.`created_by`=`pr`.`created_by`) ) LEFT JOIN `#__users` AS `u` ON `pr`.`created_by` = `u`.`id` WHERE `pr`.`virtuemart_product_id` = "689" ORDER BY created_on DESC LIMIT 0, 3