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Computed Columns into Table -Sql Server

        A computed column is a virtual column that is not physically stored in the table, unless the column is marked PERSISTED. A computed column expression can use data from other columns to calculate a value for the column to which it belongs. You can specify an expression for a computed column in in SQL Server 2016 by using SQL Server Management Studio or Transact-SQL

 CREATE TABLE dbo.Products 
(
    ProductID int IDENTITY (1,1) NOT NULL
  , QtyAvailable smallint
  , UnitPrice money
  , InventoryValue AS QtyAvailable * UnitPrice
);

 -- Insert values into the table.

 INSERT INTO dbo.Products (QtyAvailable, UnitPrice)  VALUES (25, 2.00), (10, 1.5);

 -- Display the rows in the table.

SELECT * FROM dbo.Products; 



To add a new computed column to an  existing table
ALTER TABLE dbo.Products ADD RetailValue AS (QtyAvailable * UnitPrice * 1.35);

To Change an existing column to a computed column

ALTER TABLE dbo.Products DROP COLUMN RetailValue;
GO
ALTER TABLE dbo.Products ADD RetailValue AS (QtyAvailable * UnitPrice * 1.5);
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