db:migrate rails code example

Example 1: how create migration rails

rails g migration AddPartNumberToProducts

Example 2: ruby on rails db migrate

rails db:migrate

Example 3: rials db down

bin/rails db:migrate:down VERSION=YYYYMMDDHHMMSS

Example 4: how to create an SQL table in ruby

def self.create_table
    sql = <<-SQL
      CREATE TABLE IF NOT EXISTS students (
        name TEXT,
        grade TEXT
      )
    SQL
    DB[:conn].execute(sql)
  end