ExecuteScalar

[joshmouch]

This may sound like a dumb question, but does the MySqlDirect.Net driver support the MysqlCommand.ExecuteScalar function?

I have some very simple code:

Code: Select all

Dim cmd as new MySqlCommand("SELECT 1", connection)
dim i as integer = cmd.ExecuteScalar

The function always returns a 0. This is only one test case I've tried. The more important one is executing "SELECT @@IDENTITY" after an insert, which also returns a 0.

As a reference, I run the same code on Mysql's provider without any problems.

[joshmouch]

I wrote up a test case in .Net 2.0 beta 1 using the latest version of your driver:

Code: Select all

        Dim cn As New MySqlConnection("connectionstring")
        cn.Open()
        Dim cmd As New MySqlCommand("SELECT 1", cn)
        Dim i As Integer = cmd.ExecuteScalar
        cn.Close()
        Console.WriteLine(i)
        Console.ReadLine()

This code prints a 0 intead of a 1.

[Oleg]

Thank you for information.
This problem was in beta version but we have already released MySQLDirect .NET 2.70 and it doesn't have this problem.

[Guest]

Thank you for the reply.

I have version 2.70.1.0 of the MySqlDirect.Net Driver, 2.0 beta1 of .Net, and 4.0 of mysql server.

Any other ideas?

Thank you for information.
This problem was in beta version but we have already released MySQLDirect .NET 2.70 and it doesn't have this problem.

[Oleg]

The problem is in .NET Framework 2.0 beta. To check it just decompile System.Data.ProviderBase.DbCommandBase.ExecuteScalar method and you can see the next code:

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Public Overrides Function ExecuteScalar() As Object
      Using reader1 As IDataReader = MyBase.ExecuteReader
            Dim flag1 As Boolean = False
            Do
                  If (0 < reader1.FieldCount) Then
                        flag1 = True
                        Exit Do
                  End If
            Loop reader1.NextResult
            If (flag1 AndAlso reader1.Read) Then
                  reader1.GetValue(0)
            End If
      End Using
      Return Nothing
End Function

It always returns Nothing. If this problem remains in the further versions of .NET Framework 2.0 we'll solve it at the level of our provider.

[Guest]

I don't think that beta 2 will be out until well into next year. Until then, couldn't you add your own implementation of ExecuteScalar to get it working correctly? Something similar to this:

Code: Select all

		public object ExecuteScalar()
		{
			object val = null;
			MySqlDataReader reader = ExecuteReader();
			if (reader.Read())
				val = reader.GetValue(0);
			reader.Close();

			return val;
		}

[Oleg]

We'll fix this problem at the next build of MySQLDirect .NET.