使用 ExecuteReader 时，C# 从存储过程中捕获返回值

Question

I'm trying to capture the return value from a stored proc, it should return 1, but the below C# code always shows 0 instead.

I do know that you should only read values of output paramers and the return value AFTER the datareader has been closed, but I am doing that and it still is using the wrong value.

            using (SqlConnection con = new SqlConnection(connectionString))
            {
                con.Open();

                con.InfoMessage += (object obj, SqlInfoMessageEventArgs e) => {
                    spPrintOutput2.Add(e.Message);
                };

                SqlCommand cmd = new SqlCommand(sql, con);
                cmd.CommandTimeout = 60 * 60;   // 1 hour timeout
                cmd.Parameters.Add("@returnValue", System.Data.SqlDbType.Int).Direction
                    = System.Data.ParameterDirection.ReturnValue;

                using (SqlDataReader dataReader = cmd.ExecuteReader())
                {
                    do
                    {
                        while (dataReader.Read())
                            spPrintOutput2.Add(dataReader[0].ToString());
                    } while (dataReader.NextResult());
                }

                spReturnValue = (int)cmd.Parameters["@returnValue"].Value;  // *** Should be 1 but it is 0

                cmd.Dispose();
            }

Answer 1

You forgot to specify CommandType.StoredProcedure . By default the command type is CommandType.Text , which does not expect a return value.

Try adding:

cmd.CommandType = CommandType.StoredProcedure;