defmodule Coba do
    def connect_db do
        opts = [backoff_type: :stop, hostname: "localhost", username: "budi", password: "123456", database: "dbname123", ssl: false]
        {:ok, pid} = Postgrex.start_link(opts)
        {:ok, res} = Postgrex.query(pid, "SELECT kolom1 FROM tablecoba", [])
    end
end

Coba.connect_db()