1- a> [5pts] Create the new table by writing and executing a full SQL DDL statement based on the following schema:

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1 1. [20pts] To track the history of financial information changes such as a driver s bank account, you are going to create a table to store the history of all bank account numbers. Once created, this table will track the bank account information. That is, when an insertion is made to the Driver table, the bank account information (routing number and account number) should also be inserted into this table. Also, whenever an update regarding the bank account number (the routing and/or account number) is made for a current Driver, their new bank account information should be inserted into this table after the update is successfully executed. 1- a> [5pts] Create the new table by writing and executing a full SQL DDL statement based on the following schema: Bank_Account_History (did: INTEGER, bank_account_number: VARCHAR(20), bank_account_routing_number: VARCHAR(20), operation_datetime: DATETIME) The did field refers to a driver s ID. The Operation_datetime column will store the datetime when a given record was inserted into this table. Make sure to include the appropriate PK and FK specifications in your DDL statement. CREATE TABLE Bank_Account_History ( did INTEGER, bank_account_number VARCHAR(20), bank_account_routing_number VARCHAR(20), operation_datetime DATETIME, PRIMARY KEY (did, bank_account_number, bank_account_routing_number), FOREIGN KEY (did) REFERENCES Drivers(did) ); 1- b> [5pts] Write a SQL INSERT statement that inserts the currently stored bank account information for every driver into your new Bank_Account_History table. Use the current datetime to fill in the initial operation_datetime field. You should need only one SQL INSERT statement to insert the information for all drivers. Your INSERT statement should not have to contain any actual bank account information. INSERT INTO Bank_Account_History (did, bank_account_number, bank_account_routing_number, operation_date) SELECT did, bank_account_number, bank_account_routing_number, now() from Drivers; 1- c> [5pts] Create a TRIGGER that inserts a driver s bank_account information into the Bank_Account_History table after a new driver has been successfully inserted into the Drivers table. Use the datetime when the insertion is made to fill in the operation_datetime field. The trigger name should be DRIVER_INSERT_TRIGGER. Your DDL should conform to the following template. That is, start your SQL statements with DELIMITER // and finish your statements with DELIMITER ;. 1

2 DELIMITER // CREATE TRIGGER DELIMITER ; DELIMITER // CREATE TRIGGER DRIVER_INSERT_TRIGGER AFTER INSERT ON Drivers FOR EACH ROW BEGIN INSERT INTO Bank_Account_History (did, bank_account_number, bank_account_routing_number, operation_date) VALUES (NEW.did, NEW.bank_account_number, NEW.bank_account_routing_number, now()); END;// DELIMITER ; 1- d> [5pts] Create a TRIGGER that inserts a driver s new bank_account information into the Bank_Account_History table whenever the bank account information for a driver has been updated in the Drivers table. Use the current datetime when the update occurs to fill in the operation_datetime field. The trigger name should be DRIVER_UPDATE_TRIGGER. Your DDL should conform to the template used in the question 1- c. DELIMITER // CREATE TRIGGER DRIVER_UPDATE_TRIGGER AFTER UPDATE ON Drivers FOR EACH ROW BEGIN IF NEW.bank_account_number!= OLD.bank_account_number OR NEW.bank_account_routing_number!= OLD.bank_account_routing_number THEN INSERT INTO Bank_Account_History (did, bank_account_number, bank_account_routing_number, operation_date) VALUES (OLD.did, NEW.bank_account_number, NEW.bank_account_routing_number, now()); END IF; END;// DELIMITER ; 2. [20 pts] Currently, deleting a customer does not automatically delete the associated credit cards of the customer being deleted. Therefore, a Deliber employee needs to issue two SQL statements to delete a customer and their associated credit card information. Your goal is to reduce this overhead. Specifically, when a customer is deleted, you want the associated credit card information to be automatically deleted as well. 2- a> [10 pts] Suppose for a moment that you were designing the Credit_Cards table from scratch. Explain how you would modify the following (incomplete) DDL statement in order to enforce referential integrity as desired between the Customers and Credit_cards tables. 2

3 CREATE TABLE Credit_cards_new ( card_number VARCHAR(20), expr_date CHAR(6), cid INTEGER, PRIMARY KEY (card_number) ); CREATE TABLE Credit_cards_new ( card_number VARCHAR(20), expr_date CHAR(6), cid INTEGER, PRIMARY KEY (card_number), FOREIGN KEY (cid) REFERENCES Customers(cid) ON DELETE CASCADE ); 2- b> [10 pts] Since you cannot just drop the Credit_cards table and recreate it, an ALTER TABLE statement is the only viable option. Write and execute an ALTER TABLE statement to modify the Credit_cards table to enforce referential integrity as desired for future operations. Assume that you don t have any FK in the Credit_cards table. ALTER TABLE Credit_cards ADD FOREIGN KEY (cid) REFERENCES Customers(cid) ON DELETE CASCADE; 3. [20 pts] Currently, the Order_track_status table does not present a very intuitive result to answer customer status inquiries. Thus, you are to create a view that displays the status of a given order in a single row rather than displaying multiple rows per order. 3- a> [15 pts] Write and execute a CREATE VIEW statement to create a view named Orders_status_view that has the following schema. (If the datetime of a given status change does not yet exist, let it be NULL.) Orders_status_view (oid, order_customer, order_restaurant, order_initialized_datetime, order_being_prepared_datetime, order_being_delivered_datetime, order_delivered_datetime) An example record might be: (1, Patrick M. Tyler, Pat Urban Seoul, :34:34, :44:34, :54:34, :24:34 ) CREATE VIEW Order_Status_view(oid, order_customer, order_restaurant, o_start_datetime, o_prepare_datetime, o_delivering_datetime, o_delivered_datetime) AS (SELECT DISTINCT o.oid, Users.name, Restaurants.name, o1.order_status_datetime, o2.order_status_datetime, o3.order_status_datetime, o4.order_status_datetime FROM Orders_track_status o 3

4 LEFT JOIN Orders_track_status o1 ON (o1.order_status_code=1 and o.oid=o1.oid) LEFT JOIN Orders_track_status o2 ON (o2.order_status_code=2 AND o1.oid=o2.oid) LEFT JOIN Orders_track_status o3 ON (o3.order_status_code=3 AND o1.oid=o3.oid) LEFT JOIN Orders_track_status o4 ON (o4.order_status_code=4 AND o1.oid=o4.oid) JOIN Orders ON (o1.oid=orders.oid) JOIN Restaurants ON (Orders.rid=Restaurants.rid) JOIN Users ON (Orders.cid=Users.id) ORDER BY oid); 3- b> [5 pts] Execute the following SQL statement to retrieve an order (oid: 15). SELECT * FROM Order_Status_view WHERE oid = 15; oid order_customer order_restaurant o_start_datetime o_prepare_datetime o_delivering_datetime o_delivered_datetime 15 Patrick M. Tyler Sar Tang 190 1/15/15 14:22 1/15/15 14:24 1/15/15 14:28 1/15/15 14:53 4. [20 pts] Write a SQL GRANT statement that would give the user named deliberuser read access (and only read access!) to the Orders_status_view. They should also be allowed to give the same privilege to other users. GRANT SELECT ON deliber.orders_status_view TO deliberuser WITH GRANT OPTION; 5. [20 pts] Last but certainly not least, since the site is starting to run too slowly, it is time to create some indexes to accelerate some important queries execution speeds. You want to focus on customer name lookups to find the status of an order quickly. You also want to add an index on the Orders table so that total_amount based analysis queries will run faster. 5- a> [4pts] Show the query plan for each of the following queries before you create the two indexes for these tables. First, check the visual query plan for each query by copying and pasting the following SQLs and clicking the lightning + magnifier button in MySQLWorkBench. You are not required to submit the visual query plan. You need to submit the textual query plan of each of the following queries. To create a textual query result, you can use EXPLAIN in front of each query to see the query plan in text. (e.g., EXPLAIN SELECT id, ) i) SELECT id, name FROM Users WHERE name LIKE "Ja%"; ii) SELECT id, name FROM Users WHERE name LIKE "%an"; iii) SELECT oid, total_amount FROM Orders WHERE total_amount > 100; 4

CREATE INDEX ix_users_name ON Users(name); 5- c> [4pts] Write and execute a CREATE INDEX statement that creates an index on the Orders.total_amount field.

5 [EXPLAIN SELECT ] will generate a textual query plan. To help your understanding, we present the visual query plan here. i) ii) iii) 5- b> [4pts] Write and execute a CREATE INDEX statement that creates an index on the Users.name field. The index name should be ix_users_name. CREATE INDEX ix_users_name ON Users(name); 5- c> [4pts] Write and execute a CREATE INDEX statement that creates an index on the Orders.total_amount field. The index name should be ix_orders_total_amount. CREATE INDEX ix_orders_total_amount ON Orders(total_amount); 5- d> [4pts] Now you have created two indexes. Check the visual query plan again for each of the following queries. Again, you are not required to submit the visual query plans. However, you are required to submit the textual EXPLAIN output of the following queries. i) SELECT id, name FROM Users WHERE name LIKE "Ja%"; ii) SELECT id, name FROM Users WHERE name LIKE "%an"; iii) SELECT oid, total_amount FROM Orders WHERE total_amount > 100; 5

i) ii) iii) 5- e> [4pts] Now, by comparing the query plan of 5- a and 5- d,

to make these queries run faster. An index can be utilized in all cases.

6 [EXPLAIN SELECT ] will generate a textual query plan. To help your understanding, we present the visual query plan here. i) ii) iii) 5- e> [4pts] Now, by comparing the query plan of 5- a and 5- d, briefly explain, in words, how the indexes are being used by the query optimizer to make these queries run faster. An index can be utilized in all cases. For ii), even if full index scan is conducted, the cost is cheaper than scanning the entire table since the size of index is much smaller. 6

Data Modelling and Databases. Exercise Session 7: Integrity Constraints

Data Modelling and Databases. Exercise Session 7: Integrity Constraints Data Modelling and Databases Exercise Session 7: Integrity Constraints 1 Database Design Textual Description Complete Design ER Diagram Relational Schema Conceptual Modeling Logical Modeling Physical Modeling