SELECT CONCAT('[n\t', GROUP_CONCAT(
  COLUMN_JSON(
    COLUMN_ADD(
      COLUMN_CREATE('mimefile1', mimefile1)
      , 'unpacked1', unpacked1
      , 'unpacked2', unpacked2
    )
    ORDER BY mimetype_file1
    SEPARATOR ',\n\t'
  ), '\n]') AS json
  FROM mycool.databasename \G;