migration with foreign key sample

many-to-many-migration.js

.createTable('farm_animals', tbl => {
  tbl.integer('farm_id')
    .unsigned()
    .notNullable()
    .references('id')
    // this table must exist already
    .inTable('farms')
  tbl.integer('animal_id')
    .unsigned()
    .notNullable()
    .references('id')
    // this table must exist already
    .inTable('animals')

  // the combination of the two keys becomes our primary key
  // will enforce unique combinations of ids
  tbl.primary(['farm_id', 'animal_id']);
});