SQL Server/T-SQL Tutorial/Table/Computed Columns — различия между версиями
Admin (обсуждение | вклад) м (1 версия) |
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Версия 16:46, 26 мая 2010
Computed columns are (by default) virtual columns not physically stored in the table.
<source lang="sql">
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>