npm install knex -g

if there is no knexfile.js - the file which contains our various database configurations.

knex init

to create a new migration:

knex migrate:make migration_name

replace migration_name with the name of the migration. something like add_details_to_users or create_comments . It will create a file that is timestamped like 20170520122711_create_ratings in './migrations'.

go to your newly created file in './migrations' and you will find

exports.up = function(knex, Promise) {

};

exports.down = function(knex, Promise) {

};

in the exports.up function, you will write code to be run when the migration runs. While exports.down is what runs to roll-back the migration. (usually used to undo what is done in exports.up). Syntax for schema building can be found here on the knex docs page. here is a sample:

exports.up = function(knex, Promise) {

  return knex.schema.createTable('ratings', function (table) {
    table.increments('id').unsigned().primary();
    table.integer('rating').notNull();
    table.integer('user_id').unsigned().notNull().references('id').inTable('users');
    table.integer('tutorial_id').unsigned().notNull().references('id').inTable('tutorials');
    table.timestamps();
  })

};

exports.down = function(knex, Promise) {
  return knex.schema.dropTable('ratings')
};

here we're creating a table called 'ratings' with the columns id, rating, user_id, tutorial_id. Each column has some properties associated with it.

Once you have finished writing the migrations, you can update the database matching your NODE_ENV by running:

knex migrate:latest

To rollback the last batch of migrations:

knex migrate:rollback

Migrations are run in the order they were created so try and create main tables and columns before you create things that depend on them.

To create a seed file, execute:

knex seed:make seed_name

replacing seed_name with what you're seeding.. users tutorials tags ..etc

this will create a file in "./seeds/dev" docs located here

To run seed files, execute:

knex seed:run

We will be numbering our seed files as such

1_users_see.js
2_posts_seed.js