Question

I followed an example on stackoverflow about how to read database records into variables. This is the first time doing this and I feel that I’m close but I’m baffled at this point about the problem.

Here is the link I am referring to:
Visual Basic 2010 DataSet

My code is shown below.

 Public Class Form1
        ' DataSet/DataTable variables
        Dim testdataDataSet As New DataSet
        Dim dttestdataDataTable As New DataTable
        Dim datestdataDataAdapter As New Odbc.OdbcDataAdapter

       ' Variables for retrieved data
       ' Dim sSpeed As String = ""
       ' Dim sFuelprice As String = ""
       Dim sSpeed As Integer
       Dim sFuelprice As Integer


       'Connect to the database 
       ''

       'Fill DataSet and assign to DataTable
       datestdataDataAdapter.Fill(TestdataDataSet , "TestdataDataSet")
       dttestdataDataTable = TestdataDataSet.Tables(0)

      'Extract data from DataTable
      ' Rows is the row of the datatable, item is the column

      sSpeed  = dtTestdataDataTable.Rows(0).Item(0).ToString
      sFuelprice  = dtTestdataDataTable.Rows(0).Item(1).ToString

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    result.Text = Val(miles.Text) * sSpeed * sFuelprice
End Sub

End Class

Basically, I am getting declaration errors and I don’t understand why since the example I was following clearly declared them. I’m connecting to an Access DB called “testdata.mdb” which contains only 1 record with two fields that I want to use throughout the program. The exanple said to dim the variables for each field as strings but this created more dim errors so I made them into integers and remarked out the original dim statements in the meantime (since they’re going to be used in calculations.) The dataadapter and datatable variables also are getting flagged for not being declared when they were earlier in the program. I know this must be a simple thing to fix but I’m just not seeing it.

The form is just a simple thing where the user types in a number and a result is produced by using the numbers read in from the database. In short, I want to be able to do simple calculations with a database within a program and the dim statement thing is getting in the way.

If someone can please clarify what I should do, that would be very much appreciated. Thanks!

Answer 1

I apologize for the delay in writing the answer to close off this question and sum it up.

In my case, it dataset is a one row database called testdata and contains 20 fields.

The solution that worked is as follows:

Immediately after the form1_load event, the variables can be immediately written after the dataadapter line:

  Me.TestdataTableAdapter.Fill(Me.fooDataSet.testdata)

  speed = Me.fooDataSet.testdata(0).speed
  fuelprice = Me.fooDataSet.testdata(0).fuelprice
  mpg = Me.fooDataSet.testdata(0).mpg

Then just DIM the variables to whatever you want them to be (in this case, speed is an integer, fuelprice is a decimal and MPG is a decimal) right after the PUBLIC CLASS statement at the top of your form’s code.

You can then manipulate the variables in calculations after a button click as such:

 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        fuelcost = CDec((miles.Text/ mpg) * fuelprice)
        txtfuelcost.Text = fuelcost.ToString
 End Sub

Thank you all for your responses!