run migration file rails code example

Example 1: how create migration rails

rails g migration AddPartNumberToProducts

Example 2: rails g migration add columns

$ rails generate migration AddDetailsToProducts part_number:string price:decimal

Example 3: run a specific migration rails

rake db:migrate:up VERSION=20090408054532

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