The following is a simple C# application that connects to Oracle Database and displays its version number before disconnecting using ODP.NET, Unmanaged Driver:

// C#
 
using System; 
using Oracle.DataAccess.Client;
 
class Sample
{
  static void Main()
  { 
    // Connect to Oracle
    string constr = "User Id=scott;Password=tiger;Data Source=oracle";
    OracleConnection con = new OracleConnection(constr);
    con.Open();
 
    // Display Version Number
    Console.WriteLine("Connected to Oracle " + con.ServerVersion); 
 
    // Close and Dispose OracleConnection
    con.Close();
    con.Dispose();
  }
}

If you are using ODP.NET, Managed Driver or ODP.NET Core, then replace the contents of Program.cs with the following C# code. The namespace of ODP.NET, Managed Driver (Oracle.ManagedDataAccess.*) is different from the namespace of ODP.NET, Unmanaged Driver (Oracle.DataAccess.*)

// C#
using System;
using Oracle.ManagedDataAccess.Client;
using Oracle.ManagedDataAccess.Types;
 
namespace Connect
{
  class Program
  {
    static void Main(string[] args)
    {
      try
      {
        // Please replace the connection string attribute settings
        string constr = "user id=scott;password=tiger;data source=oracle";
 
        OracleConnection con = new OracleConnection(constr);
        con.Open();
        Console.WriteLine("Connected to Oracle Database {0}", con.ServerVersion);
        con.Dispose();
 
        Console.WriteLine("Press RETURN to exit.");
        Console.ReadLine();
      }
      catch (Exception ex)
      {
        Console.WriteLine("Error : {0}", ex);
      }
    }
  }
}