1064: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'AND (link_menu = '' OR ISNULL(link_menu) ) ORDER BY orden_seccion DESC LIMIT 1' at line 1
SELECT id, nombre_seccion_menu FROM secciones WHERE orden_seccion < AND (link_menu = '' OR ISNULL(link_menu) ) ORDER BY orden_seccion DESC LIMIT 1