Northwind Question

[Wapug]

On the product details form in the Northwind database there is a "Go to Product" box that has the coding below as its row source. I cant make out what the <>Nz function is doing here. Could someone please explain this?
SELECT [ID], [Product Code], [Product Name], [List Price] FROM Products WHERE [ID]<>Nz(Form![ID],0) ORDER BY [Product Code];

 

[MarkK]

Nz() is the only creature that can eat a null without dying. In this SQL, if Form!ID is null, the Nz() function keeps things alive by returning a zero instead.

To test how this would fail without Nz(), remove the Nz() function from the SQL, and then navigate to a new record in Form (which would likely cause Form!ID to be null) and observe the result. That failure is what the Nz(), in this case, prevents.

hth
Mark