text: 
  exports.up = function(knex) {
      return knex.schema.createTable('comments', table => {
          table.bigInteger('id')
              .primary();
          table.text('body')
              .notNullable();
          table.bigInteger('postId')
              .notNullable()
              .references('id')
              .inTable('posts')
              .onUpdate('CASCADE')
              .onDelete('CASCADE')
              .notNullable();
          table.bigInteger('userId')
              .notNullable()
              .references('id')
              .inTable('users')
              .onUpdate('CASCADE')
              .onDelete('CASCADE')
              .notNullable();
          table.timestamp('createdOn')
              .defaultTo(knex.fn.now())
              .notNullable();
      })
  };
  
  exports.down = function(knex) {
      return knex.schema
          .dropTableIfExists('comments');
  };
  