ADO.NET :: Combining Data On INSERT?

I have a page with a SqlDataSource and a GridView which displays products (Title, Description, Price) pulled from a SQL table (let's call it Table1). I have added a TemplateField with a DropDownList so the buyer can choose how many they'd like. I've also added a ButtonField so the user can click to add the items to his/her shopping cart. All this works really well. The inserting is done in the Code Behind into Table2 (the code for this is provided below)

I then have a second page (ViewOrder) with a SqlDataSource and a GridView which simply displays the contents of Table2.

Here's the problem. If I add three Product 1's, ViewOrder displays a row with 3 product 1's. That's fine. But, if I then add a further 2 Product 1's, ViewOrder now displays TWO rows, one with 3 and one with 2 OF THE SAME PRODUCT.

Now, as it's the same product, I'd like ViewOrder to display ONE row with FIVE Product 1's.

Here's the code which does the Inserting into Table2:

[Code]....

myVal is the SelectedValue of the DropDownList and MealValue is a calculated value of the unit cost * myVal.