text: 
  exports.up = function (knex) {
    return knex.schema
      .createTable('scheduleGroup', function (table) {
        table.increments('id').primary().unsigned();
        table.string('serverId', 20);
        table.timestamp('created_at').defaultTo(knex.fn.now());
        table.foreign('serverId').references('id').inTable('server').onDelete('cascade');
      });
  };
  
  exports.down = function (knex) {
    return knex.schema
      .table('scheduleGroup', function (table) {
        table.dropForeign('serverId');
      })
      .dropTable('scheduleGroup');
  };
  