Reference no: EM13381105

Question 1. Update stock levels when the order is cancelled

At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean's wants to create a trigger that automatically updates the stock level of all products associated with a cancelled order and that updates the ORDERPLACED column of the BB_BASKET table to zero, reflecting that the order was not completed. Create a trigger named BB_ORDERCANCEL_TRG to accomplish this task by considering the following items:

1. The trigger needs to fire when a new status record is added to the BB_BASKETSTATUS table and when the IDSTAGE column is set to 4, which indicates order cancellation.
2. Each basket can contain multiple items in the BB_BASKETITEM table, so a CURSOR FOR loop may be an appropriate mechanism to update the stock level of each item.
3. Keep in mind that coffee can be ordered in half o whole pounds.
4. Use basket 6 for testing. Note that this basket contains two items.
   1. Open or return to SQL Plus. Execute the following statement to test the trigger:

Insert into bb_basketstatus (idstatus, idbasket, idstage, tdstage) values (bb_status_seq.nextval, 6, 4, sysdate);

1.  
   1. Execute queries to confirm that the basket order status and product stock levels have been appropriately modified by the trigger.
   2. Be sure to run the following statement to disable this trigger so that it does not affect other products:

Alter trigger bb_ordcancel_trg disable;

Question 2. Process discounts

Brewbean's is implementing a new discount for return shoppers - every fifth completed order receives a 10% discount. The count of orders for a shopper is placed in a packaged variable named PV_DISC_NUM during the ordering process. This count needs to be tested upon checkout to determine if a discount should be applied. Create a trigger named BB_DISCOUNT_TRG so that when an order is confirmed (the ORDERPLACED value is set from 0 to 1), the PV_DISC_NUM packaged variable is checked. If it is equal to 5, then set a second packaged variable named PV_DISC_TXT to 'Y'. This variable is used in calculating the order summary so that a discount is applied if appropriate.

Create a package specification named DISC_PKG that contains the needed packaged variables. Use an anonymous block to initialize the packaged variables to use for testing the trigger. Test the trigger by using the following update statement:

Update bb_basket set orderplaced =1 where idbasket=13;

Reset the ORDERPLACED to zero for the basket used (this is done as needed to complete trigger testing). Also, disable this trigger when completed so that it does not affect other assignment questions.

Question 3. Use triggers to maintain referential integrity

At times, Brewbean's has changed the id number for existing products. In the past, they have had to add a new product row with the new id to the BB_PRODUCT table, modify all the corresponding BB_BASKETITEM and BB_PRODUCTOPTION table rows, and then delete the original product row. Can a trigger be developed to avoid all these steps and handle the update of the BB_BASKETITEM and BB_PRODUCT OPTION table rows automatically for a given change in product id? If so, create the trigger and test by issuing an update statement, which changes the IDPRODUCT of 7 to 22. Do a rollback to return the data back to its original state. Also, disable the new trigger after you have completed the assignment.

Question 4. Maintain an audit trail of product table changes

The accuracy of product table data is critical and the Brwebean's. owner wants to have an audit file that contains information regarding all DML activity on the BB_PRODUCT table. This information should indicate the user id of the user running a DML statement, the date, the original values of the changed rows and the new values. The audit table needs to track specific columns of concern, including PRODUCTNAME, PRICE, SALESTART, SALEEND, and SALEPRICE. Create a table named BB_PRODCHG_AUDIT that can hold the relevant data. Then create a trigger named BB_AUDIT_TRG that fires on update to this table whenever one of the specified columns in the BB_PRODUCT table is changed.

Use the following update statement to test your trigger. Then, complete a rollback and disable the trigger when completed so that it does not affect other assignment questions.

Update bb_product set salestart = '05-MAY-03', saleend = '12-MAY-03', saleprice = 9 where idproduct = 10;

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