As the Sales Manager, execute the following statements to raise the price of all tee shirts by $0.95:

UPDATE GROUPO.Products
   SET UnitPrice = UnitPrice + 95
   WHERE Name = 'Tee Shirt';
SELECT ID, Name, UnitPrice
   FROM GROUPO.Products;

The following result set is returned:

The Sales Manager observes immediately that 0.95 should have been entered instead of 95, but before the error can be fixed, the Accountant accesses the database from another office.

The company's Accountant is worried that too much money is tied up in inventory. As the Accountant, execute the following statement to calculate the total retail value of all the merchandise in stock:

SELECT SUM( Quantity * UnitPrice )
 AS Inventory
   FROM GROUPO.Products;

The following result is returned:

Unfortunately, this calculation is not accurate. The Sales Manager accidentally raised the price of the tee shirt by $95, and the result reflects this erroneous price. This mistake demonstrates one typical type of inconsistency known as a dirty read. As the Accountant, you accessed data that the Sales Manager has entered, but has not yet committed.

As the Sales Manager, fix the error by rolling back your first change and entering the correct UPDATE statement. Check that your new values are correct.

ROLLBACK;
UPDATE GROUPO.Products
SET UnitPrice = UnitPrice + 0.95
WHERE NAME = 'Tee Shirt';

The following result set is returned:

The Accountant does not know that the amount he calculated was in error. You can see the correct value by executing the SELECT statement again in the Accountant's window.

SELECT SUM( Quantity * UnitPrice )
 AS Inventory
   FROM GROUPO.Products;

Finish the transaction in the Sales Manager's window. The Sales Manager would enter a COMMIT statement to make the changes permanent, but you should execute a ROLLBACK statement instead, to avoid changing the local copy of the SQL Anywhere sample database.

ROLLBACK;