Triggers vs. computed columns
While continuing your analysis of the database, you find two other interesting objects:
The table
SalesWithPricehas a column that calculates theTotalAmountasQuantity * Price. This is done using a computed column which uses columns from the same table for the calculation.The trigger
SalesCalculateTotalAmountwas created on theSalesWithoutPricetable. ThePricecolumn is not part of theSalesWithoutPricetable, so a computed column cannot be used for theTotalAmount. The trigger overcomes this limitation by using thePricecolumn from theProductstable.
Deze oefening maakt deel uit van de cursus
Building and Optimizing Triggers in SQL Server
Praktische interactieve oefening
Probeer deze oefening eens door deze voorbeeldcode in te vullen.
-- 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;