Need Help WithVisual Baisc

I really need help with a query in Visual basic. I have in program that insert data into a sql table, but Im trying to duplicate the data. Basically tring to make the messagebox pop up if I try insert a data into the table, which is already in the table. Can someone please help. I provided my code below

vb Code:

SQLSelect.Connection = SQLConnection
                SQLSelect.CommandText = "SELECT count(1) FROM [Inventory] WHERE  [TraceCode] ='" & TextBox1.Text & "'"
 
                SQLConnection.Open()
 
                Dim myReaders As SqlDataReader = SQLSelect.ExecuteReader()
                While myReaders.Read
                    If myReaders.Item(0) = "0" Then
 
                        SQLinsert.Connection = SQLConnection
 
                        SQLinsert.CommandText = "INSERT INTO Inventory  ([SerialNumber], [PartNumber], [VINNumber], [Status], [ProcessDate], [AllocatedDate], [RackGroup], [TraceCode], [ProcessSequence]) values ('" & TextBox2.Text & "','" & TextBox3.Text & "', '" & TextBox4.Text & "','" & TextBox5.Text & "', '" & TextBox6.Text & "','" & TextBox7.Text & "','" & TextBox8.Text & "', '" & TextBox9.Text & "','" & TextBox10.Text & "' )"
 
                        SQLinsert.Connection = SQLConnection
                        myReaders.Close()
                        SQLinsert.ExecuteNonQuery()
                       TextBox1.Text = ""
                      Exit Sub
                    
                    Else
 
                        TextBox1.Text = ""
                        MessageBox.Show("Module Already Exist In Database")
                        Exit Sub
                        Focus()
                    End If
                End While
                SQLConnection.Close()

Moved From The CodeBank (which is for sharing code rather than posting questions :) )

What happens when you step through through the code.

What you mean?

Put a breakpoint at the beginning of your code and then step through it one line at a time and see how the logic is flowing. If you don't know what I mean by that check out this link.

http://www.homeandlearn.co.uk/net/nets5p6.html