MiniOrm.cs

public abstract class Database
{
	public Database(string connectionString)
	{
		ConnectionString = connectionString;
	}

	protected string ConnectionString { get; private set; }

	public IEnumerable<IDictionary<string, object>> Query(string query, object parameters = null)
	{
		var rows = new List<IDictionary<string, object>>();

		using (var connection = CreateConnection())
		using (var command = connection.CreateCommand())
		{
			command.CommandText = query;
			
			if (parameters != null)
			{
				foreach (var parameter in ToDictionary(parameters))
				{
					var p = command.CreateParameter();

					p.ParameterName = parameter.Key;
					p.Value = parameter.Value;

					command.Parameters.Add(p);
				}
			}

			connection.Open();

			using (var reader = command.ExecuteReader())
			{
				while (reader.Read())
				{
					var values = new Dictionary<string, object>();

					for (var fieldIndex = 0; fieldIndex < reader.FieldCount; fieldIndex++)
					{
						values.Add(reader.GetName(fieldIndex), reader.GetValue(fieldIndex));
					}

					rows.Add(values);
				}
			}

			connection.Close();
		}

		return rows;
	}

	protected abstract IDbConnection CreateConnection();

	protected IDictionary<string, object> ToDictionary(object source)
	{
		var dictionary = new Dictionary<string, object>();

		foreach (PropertyDescriptor property in TypeDescriptor.GetProperties(source))
		{
			var value = property.GetValue(source);

			dictionary.Add(property.Name, value);
		}

		return dictionary;
	}
}

public class MySqlDatabase : Database
{
	public MySqlDatabase(string connectionString)
		: base(connectionString)
	{
	}
	
	protected override IDbConnection CreateConnection()
	{
		return new MySqlConnection(ConnectionString);
	}
}

public class NpgsqlDatabase : Database
{
	public NpgsqlDatabase(string connectionString)
		: base(connectionString)
	{
        }

        protected override IDbConnection CreateConnection()
        {
            return new NpgsqlConnection(ConnectionString);
        }
}