C# DbConnection Class

DbConnection.cs

using System;

namespace Sandbox
{
        public abstract class DbConnection
        {
            public string ConnectionString { get; set; }
            public TimeSpan Timeout { get; set; }

            public DbConnection(string connectionString)
            {
                if (String.IsNullOrWhiteSpace(connectionString))
                    throw new ArgumentException("Connection string cannot be empty");
                this.ConnectionString = connectionString;
            }

            public abstract void Open();
            public abstract void Close();
        }

        public class SqlConnection : DbConnection
        {
            public SqlConnection(string connectionString) : base(connectionString)
            {}

            public override void Open() => Console.WriteLine("Open SQL connection");
            public override void Close() => Console.WriteLine("Close SQL connection");
        }
        
        public class OracleConnection : DbConnection
        {
            public OracleConnection(string connectionString) : base(connectionString)
            {}

            public override void Open() => Console.WriteLine("Open Oracle connection");
            public override void Close() => Console.WriteLine("Close Oracle connection");
        }
}