You enter the expression in the Field cell in the query design grid. The fields you reference in the expression are from the tables or queries in the current query.
| Expression | Description | 
|---|---|
| Cat: (SELECT [CategoryName] FROM [Categories] WHERE [Products].[CategoryID]=[Categories].[CategoryID]) | Displays the CategoryName if the CategoryID from the Categories table is the same as the CategoryID from the Products table. |