text: exports.up = async knex => {
    return knex.schema
      .alterTable('action', table => {
        table.integer('tweetId').nullable().alter()
        table.dropForeign(null, 'action_tweetid_foreign')
        table.foreign('tweetId')
          .references('id')
          .inTable('tweet')
          .onDelete('SET NULL')
      })
  }
  
  exports.down = async knex => {
    return knex.schema
      .alterTable('action', table => {
        table.dropForeign(null, 'action_tweetid_foreign')
        table.integer('tweetId').notNullable().alter()
        table.foreign('tweetId')
          .references('id')
          .inTable('tweet')
      })
  }