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Thread: No results from sql query

  1. #1

    Thread Starter
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    Arrow No results from sql query

    Hi.
    Got a small problem here. Trying to read data from an Access 2007 database but I'm getting nowhere.
    What I do know is that everything is spelled correctly and that the database actually contains data.
    I get no error and the form launches but the labeltext is not changed.

    thanks

    btw, Using VS 2008

    Code:
    Imports System.Data.OleDb
    Public Class Form1
        Private conStr As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\SoccerQuiz.accdb;Jet OLEDB:Database Password=I_hate_Inter"
        Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    
            ReadData(conStr, "SELECT * FROM Tabell")
    
        End Sub
        Public Sub ReadData(ByVal connectionString As String, _
                        ByVal queryString As String)
            Using connection As New OleDbConnection(connectionString)
                Dim command As New OleDbCommand(queryString, connection)
    
                connection.Open()
                Dim reader As OleDbDataReader = command.ExecuteReader()
                While reader.Read()
                    lblTest.Text = reader(0).ToString()
                    'Console.WriteLine(reader(0).ToString())
                End While
                reader.Close()
            End Using
        End Sub
    End Class
    this code doesn't work either:
    Code:
            conn = New OleDbConnection(connstring)
            conn.Open()
            Dim cmd As New OleDbCommand(sql_query, conn)
            Try
                Dim reader As OleDbDataReader = cmd.ExecuteReader()
                While reader.Read()
                    MessageBox.Show(reader.GetValue(0).ToString())
                End While
                reader.Close()
            Catch err As OleDbException
                MessageBox.Show(err.Message)
            Finally
                conn.Close()
            End Try
    FORZA ROSSONERI! CAMPIONI!!!

  2. #2
    I'm about to be a PowerPoster! Hack's Avatar
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    Re: No results from sql query

    Try this
    Code:
    Imports System.Data.OleDb
    
    Public Class Form1
    
        Private connstring As String = "Your connection string"
        Private conn As OleDb.OleDbConnection
    
        Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            conn = New OleDbConnection(connstring)
            conn.Open()
        End Sub
    
        Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
            Dim sSQL As String = String.Empty
            sSQL = "SELECT * FROM Tabell "
            Dim command As New OleDbCommand(sSQL, conn)
            Dim reader As OleDbDataReader = command.ExecuteReader()
            ListBox1.Items.Clear()
           If reader.HasRows = True Then 'make sure there is data returned
                 While reader.Read()
                          ListBox1.Items.Add(reader.GetString(0))
                  End While
           Else
                  MessageBox.Show("No data matched your search criteria.")
           End If
            reader.Close()
        End Sub
    End Class
    You are returned multiple records so I would suggest using something other than a label.

  3. #3

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    Re: No results from sql query

    Thanks Hack.
    While this did not solve my problem I now get errors that I can try to resolve. For example "Microsoft.ACE.OLEDB.12.0-provider is not registerd on the computer". (Wich I guess is a big reason why it wont work ). I will try to figure this out in the morning. If someone knows how to fix this so that I don't need to spend an hour on Google I would be a very hapy dude
    Thanks again.
    Last edited by Rossonero; Nov 14th, 2008 at 07:52 PM.
    FORZA ROSSONERI! CAMPIONI!!!

  4. #4
    Super Moderator jmcilhinney's Avatar
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    Re: No results from sql query

    Quote Originally Posted by Rossonero
    Thanks Hack.
    While this did not solve my problem I now get errors that I can try to resolve. For example "Microsoft.ACE.OLEDB.12.0-provider is not registerd on the computer". (Wich I guess is a big reason why it wont work ). I will try to figure this out in the morning. If someone knows how to fix this so that I don't need to spend an hour on Google I would be a very hapy dude
    Thanks again.
    That means that the system it's being run on doesn't have any Office drivers installed. To get the Access 2007 OLEDB provider you have to either install Access 2007 or the Office driver pack.

    http://www.microsoft.com/downloads/d...displaylang=en

    With regards to your original issue, you were using a While loop and testing the result of the DataReader's Read method. Most likely the method never returned True so the loop was never entered. That means that the query returned no data. You can confirm that by testing the reader's HasRows property.
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  5. #5

    Thread Starter
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    Re: No results from sql query

    Thanks everybody.
    FORZA ROSSONERI! CAMPIONI!!!

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