updating particular columns of information dependent on whether it's filled/altered

I haven't written the whole statement yet (I am having trouble writing the Update statement...) But, below is what I think I can get done. But as I said, I don't think it's "correct"



Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' Each Dim is a separate input. Sometimes they will be typed into, othertimes they won't. I want to be able to update the row's column, only if it's required.

Dim ourcost As Double = CDbl(Our_CostTextBox.Text)
Dim quote As Boolean = QuoteCheckBox.Checked
Dim accept As Boolean = AcceptCheckBox.Checked
Dim price As Double = CDbl(PriceTextBox.Text)
Dim fixcon As String = FixConTextBox.Text
Dim ra As String = RA_IDComboBox.Text
' The only way I can think of how to do this, is if statements for each variable. And to check that the variable has something in it. But, if it already has a value in it, I don't want it to update.

If ourcost >= 0 Then
ourcostsub(ra, ourcost)
End If

'My dodgey update statement, I'm currently just getting my head around how to work with the data, so I'm aware of SQL parameters to stop injection, but I just want to get something working for now so I understand, and then once I've done that go through and fix the code up.

sub ourcostsub(byval ra as string, byval ourcost as Double)
" update RA(our_cost) " & _
" Set ( " & _
"'" & ourcost & "'" & _
" Where(RA_ID = '" & ra & "')"

:) I got my update statement properly...Besides not using sql parameters.. i'll get that bit done shortly.

Dim insertqry As String = " update RA " & _
" Set our_cost = " & _
"'" & ourcost & "'" & _
" Where RA_ID = '" & ra & "'"
Dim sqlconnection As New SqlConnection(Main.connectionstring)
Dim command As New SqlCommand(insertqry, sqlconnection)

Try
SqlConnection.Open()
command.ExecuteNonQuery()
Catch ex As Exception
MessageBox.Show("Error while inserting record on table..." & ex.Message, "Insert Records")
Finally
SqlConnection.Close()
End Try