SQL Server/T-SQL Tutorial/Table/Computed Columns

Computed columns are (by default) virtual columns not physically stored in the table.

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Their values are recalculated each time they are referenced in a query. CREATE TABLE orders

       (orderid INT NOT NULL,
       price MONEY NOT NULL,
       quantity INT NOT NULL,
       orderdate DATETIME NOT NULL,
       total AS price * quantity PERSISTED,
       shippeddate AS DATEADD (DAY, 7, orderdate))

GO drop table orders; GO</source>