MicroSoft SQL Server column expressions can simplify some of the logic in your database schema or application logic by allowing expressions to derive the value of a database table column.

For example;

I was needing to perform some basic calculations for order line items. Rather than creating a trigger to multiple the QTY ordered by the selling PRICE of the item and place that value in the TOTAL column, I used an expression in the TOTAL column to do this multiplication for me. Here is a screenshot.


 
After this setup on the column, you will find that all records will have the proper order total automatically. No need to code triggers, put in application logic to calculate and update the value.

In real world usage I am sure it will not be this simple. You will want to make careful choices about what belongs in the column spec. or in the business rule logic.

Best of luck.