VS 2008 - Search Item By DataGridView Column

Data in Table1 is as follows
Code-------product--------weight
1-------------Apple----------2.00
2-------------Mango---------3.25
3-------------Banana---------6.50

Then I have Datagridview with three columns same as
Code, Product, Weight

I have following codes
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
str = "SELECT desc1,weight FROM master where code =" & Val(DataGridView1.Rows(0).Cells(0).Value)
dt = GetTable(str)
If dt.Rows.Count > 0 Then
DataGridView1.Rows(0).Cells(1).Value = Trim(dt.Rows(0).Item(0))
DataGridView1.Rows(0).Cells(2).Value = Trim(dt.Rows(0).Item(1))
End If
End Sub

When I enter 1 in row(0).cells(0) then other two columns fill automatically, but when enter 2 in next row then nothing retreived from database.I think this line should me modified as current row and current column.
str = "SELECT desc1,weight FROM master where code =" & Val(DataGridView1.Rows(0).Cells(0).Value)