Web Forms :: Get Old Values Of Gridview Textbox To Compare Before Inserting?

I need to compare the old value of my textbox to the new value that was put intot he checkbox to see if anything changed alse I don't wnat to save anything in the wor and move to next row. Here is my gridiview with bound txtBoxes and my initial code behind.

<asp:TemplateField HeaderText="ACTUAL">
<ItemTemplate>
<asp:TextBox ID="txtActual" runat="server" Text='<%# Eval("ACTUAL_VALUE") %>' Width="60" MaxLength="8"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="TARGET">
<ItemTemplate>
<asp:TextBox ID="txtTarget" runat="server" Text='<%# Eval("TARGET_VALUE") %>' Width="60" MaxLength="8"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="TOLERANCE">
<ItemTemplate>
<asp:TextBox ID="txtTolerance" runat="server" Text='<%# Eval("TOLERANCE_RAW") %>' Width="120" MaxLength="8"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>

I save a linkbutton to save it all. but I need to compare values so that I am not saving information that does not need to be saved becuase of the expensive long trip of the update process to an oracle server over a link from sql.

For Each dgi As GridViewRow In Gridmain.Rows
Dim Actualval As String = CType(dgi.FindControl("txtActual"), TextBox).Text
Dim Targetval As String = CType(dgi.FindControl("txtTarget"), TextBox).Text
Dim Tolval As String = CType(dgi.FindControl("txtTolerance"), TextBox).Text
Dim BMVal1 As String = CType(dgi.FindControl("txtBm1"), TextBox).Text
Dim BMVal2 As String = CType(dgi.FindControl("txtBm2"), TextBox).Text
Dim BMVal3 As String = CType(dgi.FindControl("txtBm3"), TextBox).Text
Dim BMVal4 As String = CType(dgi.FindControl("txtBm4"), TextBox).Text
Dim BMVal5 As String = CType(dgi.FindControl("txtBm5"), TextBox).Text
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