What is the exact error you see? What behaviour did you observe, which did you expect?

Since you’re using MySQL, you probably want to use MyXQL.

GitHub: https://github.com/elixir-ecto/myxql
Docs: https://hexdocs.pm/myxql/readme.html

It is possible to use raw drivers? Yes.
Suppose you want to use on a simple, not phoenix project
creating a project using mix new my_app --sup will create the folders and the implementation of Application (the main entry point) which starts the supervision tree.

defmodule MyApp.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  def start(_type, _args) do
    # List all child processes to be supervised
    children = [
      # Starts a worker by calling: MyApp.Worker.start_link(arg)
      # {MyApp.Worker, arg}
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

Now the driver is just a “Worker” and we can start under the supervisor.

• Add {:myxql, "~> 0.2.0"} to your dependencies and run mix deps.get, this is a new driver made for newer versions of mysql

• Supports MySQL 5.7.10+, 8.0, and MariaDB 10.3

• Now under the MyApp.Application.start/2 function we have the children list, there we will add the initialization for the driver.

children = [
  {MyXQL, hostname: "10.10.11.11", username: "username", password: "password", database: "fortesting", name: :mydb}
]

Note that we add a key name to the options with value :mydb that is our identifier to use the same driver process in the application without the need to start/stop when a request comes.

Now on your controller action or any where you need, even on iex -S mix :

{:ok, result} = MyXQL.query(:mydb, "select * from database where ticket = ? and ver = ? and os = ?", [ticket_param, ver_param, os_param])

Performing the query with ? on the string allows the driver do the sanatization, preventing SQL Injection.

And thats it. For more infor on what you get from MyXQL.query/3 you can see the docs and the github repo

It seems like you’re just getting started with Elixir, so you might want to check out Ecto which is used by most people in the Elixir community for working with SQL databases.

Take a look at the Getting Started guide:
https://hexdocs.pm/ecto/getting-started.html

If you use ecto, then you will need a Repo, as the Repo is your wrapper around the connection pooling.

Of course you can also use postgrex (or any other driver) to directly do the low level dirty work to talk to your database…