一个DAO类，用于访问SQL server、MySQL和MongoDB中的数据库

有没有一种方法可以创建一个像EmployeeDAO这样的DAO类，并且这个类应该能够使用SQL Server、MySql和MongoDB。它应该以某种方式更改并与MySqlConnection/SqlConnection和MySqlCommand/SqlCommand一起工作。现在，我必须为每个数据库创建三个类。有什么接口我可以使用吗？我找不到。非常感谢。

public abstract class DaoFactory
{
  public static DaoFactory GetInstance(DaoConnection daoConnection)
    {
        DaoFactory instance = null;
        switch (daoConnection)
        {
                case DaoConnection.Default:
                case DaoConnection.MySQL:
            {
                instance = new MySqlConnectionFactory(MySqlServer, MySqlPort, MySqlUser, MySqlPassword);
                break;
            }
        }
        return instance;
    }
 protected string ConnectionString { get; set; }
 public abstract DbConnection GetConnection();
}
public class MySqlConnectionFactory : DaoFactory
{
    public MySqlConnectionFactory(string server, string port, string user, string password) : base(server, port, user, password)
    {
        this.ConnectionString = string.Format("Server={0}; Port={1} Uid={2}; Pwd={3}; pooling=true", server, port, user, password);
    }
    public override DbConnection GetConnection()
    {
        return new MySqlConnection(this.ConnectionString);
    }
}

public class EmployeeDao : IEmployeeDao
{
    private const string InsertEmployee = "INSERT INTO employees VALUES (@name,@age)";
    private DaoFactory daoFactory;
    EmployeeDao(DaoFactory daoFactory)
    {
        this.daoFactory = daoFactory;
    }
    public void Insert(Employee employee)
    {
        MySqlConnection connection =  (MySqlConnection) this.daoFactory.GetConnection();
        using (connection)
        {
            var commannd = new MySqlCommand(InsertEmployee, connection);
            commannd.ExecuteNonQuery();
        }
    }