SELECT
  `a`.`correo` AS `correo`,
  `a`.`nombre` AS `nombre`,
  `a`.`apellido` AS `apellido`,
  `a`.`nivel_ingles` AS `nivel_ingles`,
  `gg`.`id` AS `grados_grupos_id`,
  `gg`.`grado` AS `grado`,
  `gg`.`grupo` AS `grupo`,
  `gg`.`nivel` AS `nivel`
FROM
  (
    `edca`.`alumnos` `a`
    LEFT JOIN `edca`.`grados_grupos` `gg` ON((`a`.`grados_grupos_id` = `gg`.`id`))
  )