add_colum migration rails code example

Example 1: rails g migration add columns

$ rails generate migration AddDetailsToProducts part_number:string price:decimal

Example 2: 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