mbi.rb

# Function transfer in Account class
  def transfer(recipient_id, amount)
    result = @db.query("SELECT Balance FROM Balance WHERE AccountID = #{@account_id} ORDER BY Date DESC LIMIT 1")
    if result.first['Balance'] >= amount
      puts @db.query("CALL Transfer(#{@account_id}, #{recipient_id}, #{amount})").inspect
      puts nil.inspect
    end
  end