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: GitHub - elixir-ecto/myxql: MySQL 5.5+ driver for Elixir · GitHub
Docs: MyXQL — MyXQL v0.9.0

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