PART 1:
ALTER TABLE movies ADD num_rentals_datatype INT;
------------------
Command(s) completed successfully.

SELECT movie_id, num_rentals_datatype FROM movies
---------------
movie_id    num_rentals_datatype
1       NULL
2       NULL
3       NULL
4       NULL
5       NULL
(5 ROW(s) affected)


UPDATE movies SET num_rentals_datatype =0;
-----------------------
movie_id    num_rentals_datatype
1       0
2       0
3       0
4       0
5       0


ALTER TABLE movies ALTER COLUMN num_rentals_datatype INT NOT NULL;
---------------
Command(s) completed successfully.

PART 2:
CREATE TRIGGER tr_Customer_Rentals_insert
ON CustomerRentals FOR INSERT
        AS
        BEGIN
        UPDATE movies
        SET num_rentals_datatype = num_rentals_datatype +1
        WHERE movie_id = (SELECT movie_id FROM inserted);
        END;
----------------
Command(s) completed successfully.


CREATE TRIGGER tr_Customer_Rentals_delete
ON CustomerRentals FOR DELETE
        AS
        BEGIN
        UPDATE movies
        SET num_rentals_datatype = num_rentals_datatype -1
        WHERE movie_id = (SELECT movie_id FROM DELETED);
        END;
---------------
Command(s) completed successfully.

CREATE TRIGGER tr_Customer_Rentals_update
ON CustomerRentals FOR UPDATE
        AS
        BEGIN
        UPDATE movies
        SET num_rentals_datatype = num_rentals_datatype -1
        WHERE movie_id = (SELECT movie_id FROM DELETED);
        UPDATE movies
        SET num_rentals_datatype = num_rentals_datatype +1
        WHERE movie_id = (SELECT movie_id FROM INSERTED);
        END;
---------------------
Command(s) completed successfully.

PART 3:
INSERT INTO CustomerRentals
VALUES(2, 1, ‘Active’, ‘6/9/2018’, ‘6/12/2018’, 10.00)
--------
(1 ROW(s) affected)
(1 ROW(s) affected)

movie_id    num_rentals_datatype
1       1
2       0
3       0
4       0
5       0

UPDATE CustomerRentals
SET movie_id = 5
WHERE customer_id = 2
    AND movie=id = 1
    AND rental_date_out = ‘6/9/2018’
-----------
(1 ROW(s) affected)
(1 ROW(s) affected)
(1 ROW(s) affected)

movie_id    num_rentals_datatype
1       0
2       0
3       0
4       1
5       0

D