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Triggers vs. computed columns

While continuing your analysis of the database, you find two other interesting objects:

  • The table SalesWithPrice has a column that calculates the TotalAmount as Quantity * Price. This is done using a computed column which uses columns from the same table for the calculation.

  • The trigger SalesCalculateTotalAmount was created on the SalesWithoutPrice table. The Price column is not part of the SalesWithoutPrice table, so a computed column cannot be used for the TotalAmount. The trigger overcomes this limitation by using the Price column from the Products table.

この演習はコースの一部です

Building and Optimizing Triggers in SQL Server

コースを見る

実践的なインタラクティブ演習

このサンプルコードを完成させて、この演習に挑戦してみましょう。

-- Add the following rows to the table
INSERT INTO ___ (Customer, Product, Price, Currency, Quantity)
VALUES ('Fruit Mag', 'Pomelo', 1.12, 'USD', 200),
	   ('VitaFruit', 'Avocado', 2.67, 'USD', 400),
	   ('Tasty Fruits', 'Blackcurrant', 2.32, 'USD', 1100),
	   ('Health Mag', 'Kiwi', 1.42, 'USD', 100),
	   ('eShop', 'Plum', 1.1, 'USD', 500);

-- Verify the results after adding the new rows
SELECT * FROM SalesWithPrice;
コードを編集して実行