When using SharePoint Designer, it should be remembered that it is a fully-fledged member of the Microsoft Office suite of products. As such, we can use it to perform powerful calculations that you would expect other products in the suite (such as Excel) to perform.

We will add a new column to our data view that will display the total value of the wine the Wine Company has in stock. We begin this process by clicking on our data view to select it and then going to Data View | Edit Columns....

The Edit Columns dialog allows us to select the fields in our data set that we would like to include in our data view. If we would like to add columns to or remove columns from our data view, this is the dialog that we would use.

The dialog also allows us to add a formula column. We will do this now by clicking on Add Formula Column... and then clicking on the Add >> button.

The XPath Expression Builder then appears. If you have previously created formulae in Microsoft Excel or Microsoft...