c# - How can I get the return value from Sql Server system message?

Question

I am trying to verify the backup I have just done in c# using command against sql server Express

 string _commandText =  string.Format("RESTORE VERIFYONLY FROM DISK = '{0}'", backupLocation);

 SqlDataReader _sqlDataReader = SqlHelper.ExecuteReader("BookssortedSQLDbConnection", CommandType.Text, _commandText);

If I execute the command in SSMS it returns 'The backup set on file 1 is valid.' but how can I get this message back into my code?

A reader wont work as there are no rows being returned.

NOTE: I have tried the SMO.Restore object to try and verify it but it doesn't work and that is why I am doing it this way.

_restore.SqlVerify(srv, out _errorMessage); //returns false even though bakcup is fine

BTW - Open to suggestions as I don't think this is the ideal way to achieve what I am trying to do

Answer 1

Informational messages (with severity less than 10) and PRINT output are returned to the client, and raised as InfoMessage events by the SqlConnection instance. Each event contains a collection of SqlError objects (this is the same class used in SqlException.Errors).

Here's a complete example that shows connection state changes, info messages and exceptions. Note that I use ExecuteReader instead of ExecuteNonQuery, but the info and exception results are the same.

namespace Test
{
    using System;
    using System.Data;
    using System.Data.SqlClient;

    public class Program
    {
        public static int Main(string[] args)
        {
            if (args.Length != 2)
            {
                Usage();
                return 1;
            }

            var conn = args[0];
            var sqlText = args[1];
            ShowSqlErrorsAndInfo(conn, sqlText);

            return 0;
        }

        private static void Usage()
        {
            Console.WriteLine("Usage: sqlServerConnectionString sqlCommand");
            Console.WriteLine("");
            Console.WriteLine("   example:  "Data Source=.;Integrated Security=true" "DBCC CHECKDB"");
        }

        public static void ShowSqlErrorsAndInfo(string connectionString, string query)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                connection.StateChange += OnStateChange;
                connection.InfoMessage += OnInfoMessage;

                SqlCommand command = new SqlCommand(query, connection);
                try
                {
                    command.Connection.Open();
                    Console.WriteLine("Command execution starting.");
                    SqlDataReader dr = command.ExecuteReader();
                    if (dr.HasRows)
                    {
                        Console.WriteLine("Rows returned.");
                        while (dr.Read())
                        {
                            for (int idx = 0; idx < dr.FieldCount; idx++)
                            {
                                Console.Write("{0} ", dr[idx].ToString());
                            }

                            Console.WriteLine();
                        }
                    }

                    Console.WriteLine("Command execution complete.");
                }
                catch (SqlException ex)
                {
                    DisplaySqlErrors(ex);
                }
                finally
                {
                    command.Connection.Close();
                }
            }
        }

        private static void DisplaySqlErrors(SqlException exception)
        {
            foreach (SqlError err in exception.Errors)
            {
                Console.WriteLine("ERROR: {0}", err.Message);
            }
        }

        private static void OnInfoMessage(object sender, SqlInfoMessageEventArgs e)
        {
            foreach (SqlError info in e.Errors)
            {
                Console.WriteLine("INFO: {0}", info.Message);
            }
        }

        private static void OnStateChange(object sender, StateChangeEventArgs e)
        {
            Console.WriteLine("Connection state changed: {0} => {1}", e.OriginalState, e.CurrentState);
        }
    }
}