CODEWITHSUNDEEP
vb.net
user1932402
user1932402

Reputation:

Conversion type Integer Misunderstanding

I am sorry for my bad english. I hope somebody could explain what the error The conversion from type MySqlDataReader to type Integer is invalid means.

I was sure that it was a simple 'Dim a Integer, but It is larger than that, or I am just been stupid.

My btnLogin_Click code:

Dim SQL As New MySQLHook
Dim loginResult As Integer

Dim User As TextBox = Me.Controls.Item("TextGebruikersNaam")
Dim Pass As TextBox = Me.Controls.Item("TextGebruikersPass")

If String.IsNullOrEmpty(User.Text) Or String.IsNullOrEmpty(Pass.Text) Then
    MsgBox("Voer een gebruikersnaam en wachtwoord in om verder te gaan.", MsgBoxStyle.Exclamation, "Foutmelding")
    User.Focus()
Else
    loginResult = SQL.Results("SELECT * FROM tblgebruikers " & "WHERE GebruikersNaam='" & User.Text & "' AND " & "GebruikersPass='" & Pass.Text & "'")

    If loginResult = 1 Then
        ' Login was good, todo: add code here
    Else
        MsgBox("De gebruikersnaam of wachtwoord is onjuist. Probeer het opnieuw of vraag een nieuw wachtwoord aan.", MsgBoxStyle.Exclamation, "Foutmelding")
        User.Text = ""
        Pass.Text = ""
        User.Focus()
    End If
End If

My Results code (SQL.Results is from As New MySQLHook)

Public Function Results(ByVal sql)
    Try
        Dim conn = Connect()

        Dim myAdapter As New MySqlDataAdapter
        Dim myCommand As New MySqlCommand()

        myCommand.Connection = conn
        myCommand.CommandText = sql

        myAdapter.SelectCommand = myCommand

        Dim myData As MySqlDataReader

        myData = myCommand.ExecuteReader()
        Return myData
    Catch myerror As MySqlException
        clsError.logMessage("De server retourneerde de volgende foutmelding: " & myerror.Message)
        Return DBNull.Value
    End Try
End Function

I olso tried using this function but it gave me the same error message:

Public Function num_results(ByVal sql)
Try
    Dim conn = Connect()

    Dim myAdapter As New MySqlDataAdapter
    Dim myCommand As New MySqlCommand()

    myCommand.Connection = conn
    myCommand.CommandText = sql
    myAdapter.SelectCommand = myCommand

    Dim myData As MySqlDataReader

    myData = myCommand.ExecuteReader()
    Return myData
Catch myerror As MySqlException
    clsError.logMessage("De server retourneerde de volgende foutmelding: " & myerror.Message)
    Return DBNull.Value
End Try
End Function

Why does this conversion error pop-ups? I was sure that 1 or 0 is self-explaining.

Upvotes: 0

Views: 132

Answers (1)

driis
driis

Reputation: 164291

Your problem is that you are creating a data reader and returning that. You need to read the integer from the myData variable before returning it.

So, instead of:

Return myData

You should be able to use:

Return myData.GetInt32(0)

The 0 in that statement identifies the column you want to read, and since you are returning a single column from your SQL query, it is in index 0.

Once you have fixed that, please google 'SQL injection' and 'parameterized SQL queries' before continuing. Having your app open to SQL injection is a serious risk.

Upvotes: 1

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