How to count Maximum rows in Visual Basic - sql

Question

I have the code for the next button. The data in the database show up normally.
The problem is when I click next button, the data will be repeated again as --> data1 > data2 > data3 > data1 > data2...
I've to been told that I should count the maximum rows but I didn't know how to do it; I've search for the coding as well, but nothing that I understand came out.
Please help me~~~ (I am not very good with English, sorry)
Private Sub btnNext_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnNext.Click
btnBack.Enabled = True
da.Fill(dt)
If position >= 0 Then
position = position + 1
Me.lblID.Text = dt.Rows(position).Item("RefNo")
Me.txtboxName.Text = dt.Rows(position).Item("Name")
Me.rtxtboxAddress.Text = dt.Rows(position).Item("Address")
Me.txtboxContactNo.Text = dt.Rows(position).Item("ContNo")
Me.txtboxFaxNo.Text = dt.Rows(position).Item("FaxNo")
Me.txtboxBrand.Text = dt.Rows(position).Item("Brand")
Me.txtboxModel.Text = dt.Rows(position).Item("Model")
Me.txtboxSN.Text = dt.Rows(position).Item("SN")
Me.rtxtboxProblems.Text = dt.Rows(position).Item("Problems")
Me.rtxtboxTechRemark.Text = dt.Rows(position).Item("TechRemark")
Me.rtxtboxServChange.Text = dt.Rows(position).Item("ServiceChange")
Me.rtxtboxPartChange.Text = dt.Rows(position).Item("PartsChange")
Me.txtboxTotal.Text = dt.Rows(position).Item("TotalPrice")
End If
End Sub
I don't know if this is also need to be told, but... there is two different class
1) database.vb - sql coding
2) forms.vb - coding for my visual basic form
Please help me!!
THANKS EVERYONE WHO HELO ME WITH THE ANSWERS!! I HAVE FOUND THE SOLUTION OF THE QUESTION AFTER RE-FIGURED THE CODING.
I didn't figure out the position value and the row value is same. My value of position = 0 and dt.Rows.Count = 4, since I have 4 data; so when the position = 0, the row = 1. I get confused about that; I thought both value is starting with 0.

Answer 1

A bit more code... this is bad code... don't rely on it for production since I'm sure there are plenty of corner cases it doesn't handle, but I wanted to give you a picture of how you could handle it and at least a glimpse of stuff you might need to worry about (e.g. 0 rows in the data table). Please work through this and try to understand the code... don't simply copy/paste.
Private Sub btnNext_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnNext.Click
If position >= dt.Rows.Count Then
// No more rows to show after this one, so disable the next button
btnNext.Enabled = False
End If
// Put check for zero in btnBack.Click to make sure it doesn't go below 0
// I'm assuming position starts off at 0, and that you're showing the very
// first row by default
position += 1
// This is to handle a condition like having 0 rows in the data table,
// in which case don't want to do the next part...
If position > dt.Rows.Count Then Exit Sub
// Only necessary once really, but we'll do it each time anyway...
btnBack.Enabled = True
da.Fill(dt)
position += 1
// Update various textboxes and labels...
End Sub

Answer 2

dt.Rows.Count is the number of rows in the Rows collection. Anytime you want to check the whether you've reached the maximum number of rows compare the row count to dt.Rows.Count

Answer 3

da, dt, and position should be declared outside your sub above. The Fill statement should also be executed outside the sub.
In the sub:
If position >= 0 and position < dr.rows.count then
do stuff above
else
Beep ' out of range
end if