Sqlhelper calls the stored procedure to obtain the returned values and parameters

Sqlhelper extracted from Microsoft petshop. When a stored procedure is executed, the data parameter is always null.

At first, I thought my stored procedure was wrong. After the test, I found that there was no problem.

 

I also found some articles on the internet, saying that sqldatareader can be accessed after being disabled. Still unsolved

 

Later, I carefully read the sqlhelper code to find the problem, as shown below. After executing executereader, cmd. Parameters. Clear ();
The parameters are cleared. Of course, they cannot be obtained. You can finally go to bed.

        /// <summary>        /// Execute a SqlCommand that returns a resultset against the database specified in the connection string         /// using the provided parameters.        /// </summary>        /// <remarks>        /// e.g.:          ///  SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));        /// </remarks>        /// <param name="connectionString">a valid connection string for a SqlConnection</param>        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>        /// <param name="commandText">the stored procedure name or T-SQL command</param>        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>        /// <returns>A SqlDataReader containing the results</returns>        public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)        {            SqlCommand cmd = new SqlCommand();            SqlConnection conn = new SqlConnection(connectionString);            // we use a try/catch here because if the method throws an exception we want to             // close the connection throw code, because no datareader will exist, hence the             // commandBehaviour.CloseConnection will not work            try            {                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);                //cmd.Parameters.Clear();                return rdr;            }            catch            {                conn.Close();                throw;            }        }