จะทำการ update ตาราง แต่ run แล้วขึ้นว่า Syntax error in UPDATE statement

Private Sub Bedit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Bedit.Click
 If MessageBox.Show("คุณต้องการแก้ไขข้อมูลใช่หรือไม่", "คำยืนยัน", MessageBoxButtons.YesNo, MessageBoxIcon.Warning) = Windows.Forms.DialogResult.Yes Then
            sql = "UPDATE Product SET"
            sql = sql + " Product_name='" & Tproname.Text & "',"
            sql = sql + " Type_code='" & Tprotype.Text & "',"
            sql = sql + " Brand_code='" & Tprocode.Text & "',"
            sql = sql + " Color ='" & Tcolor.Text & "',"
            sql = sql + " Size ='" & Tsize.Text & "',"
            sql = sql + " Stock_Amount ='" & Tprostock.Text & "',"
            sql = sql + " Product_cost ='" & Tprocost.Text & "',"
            sql = sql + " Product_price ='" & Tprosale.Text & "',"
            sql = sql + " Store_code ='" & Tprostore.Text & "',"
            sql = sql + " Lowpro ='" & Tprolow.Text & "',"
            sql = sql + " WHERE "
            sql = sql + " Product_code ='" & Tprocode.Text & "'"



            MessageBox.Show("แก้ไขข้อมูลเรียบร้อยแล้ว")
            cmd_excuteNonquery()

        End If
        Tprobrand.Clear()
        Tprocode.Clear()
        Tprocost.Clear()
        Tprolow.Clear()
        Tproname.Clear()
        Tprosale.Clear()
        Tprostock.Clear()
        Tprostore.Clear()
        Tprotype.Clear()
        Tsize.Clear()
        Tcolor.Clear()
        refresh_Product()

    End Sub