C#执行带参数的Oracle存储过程

 public void UpdateByRowGuid(string RowGuid)
        {
//OracleConnection conn = new OracleConnection("data source=myoracle;User Id=feng;Password=feng");    //连接数据库
string connectionString = System.Configuration.ConfigurationManager.AppSettings["CoonString"].ToString();
            OracleConnection con = new OracleConnection(connectionString);
         conn.Open();                                                  //打开数据库
         OracleCommand dr = new OracleCommand("ss_xs", conn);                         //连接存储过程
         dr.CommandType = CommandType.StoredProcedure;                           //定义连接的是存储过程
         OracleParameter op = dr.Parameters.Add("sdate", OracleType.VarChar, );         //定义参数
         op.Direction = ParameterDirection.Input;                                  //定义参数是输入
         op.Value = "";                                                   //参数值
         dr.ExecuteNonQuery();                     //执行
         conn.Close();                       //关闭数据库连接
}