OcurriĆ³ un Error con la Base de Datos

Error Number: 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 'UNION SELECT titulo, url_guia,resumen_guia FROM guias where id_categoria='18'...' at line 1

SELECT titulo, url_guia,resumen_guia FROM guias where match(titulo,guia) against('Left 2 Die') and id_guia!='158' limit 4 UNION SELECT titulo, url_guia,resumen_guia FROM guias where id_categoria='18' and id_guia!='158' limit 3