CREATE TABLE SALESMAN

(SALESMAN_ID NUMBER (4),

NAME VARCHAR2 (20),

CITY VARCHAR2 (20),

COMMISSION VARCHAR2 (20),

PRIMARY KEY	(SALESMAN_ID));

CREATE TABLE CUSTOMER1

(CUSTOMER_ID NUMBER (4),

CUST_NAME VARCHAR2 (20),

CITY VARCHAR2 (20),

GRADE NUMBER (3),

PRIMARY KEY (CUSTOMER_ID),

SALESMAN_ID REFERENCES SALESMAN (SALESMAN_ID) ON DELETE SET NULL);

CREATE TABLE ORDERS

(ORD_NO NUMBER (5),

PURCHASE_AMT NUMBER (10, 2),

ORD_DATE DATE,

PRIMARY KEY (ORD_NO),

CUSTOMER_ID REFERENCES CUSTOMER1 (CUSTOMER_ID) ON DELETE CASCADE, SALESMAN_ID REFERENCES SALESMAN (SALESMAN_ID) ON DELETE CASCADE);



INSERT INTO SALESMAN VALUES (1000, ‘JOHN’,’BANGALORE’,’25 %’);

INSERT INTO SALESMAN VALUES (2000, ‘RAVI’,’BANGALORE’,’20 %’);

INSERT INTO SALESMAN VALUES (3000, ‘KUMAR’,’MYSORE’,’15 %’);

INSERT INTO SALESMAN VALUES (4000, ‘SMITH’,’DELHI’,’30 %’);

INSERT INTO SALESMAN VALUES (5000, ‘HARSHA’,’HYDRABAD’,’15 %’);


INSERT INTO CUSTOMER1 VALUES (10, ‘PREETHI’,’BANGALORE’, 100, 1000);

INSERT INTO CUSTOMER1 VALUES (11, ‘VIVEK’,’MANGALORE’, 300, 1000);

INSERT INTO CUSTOMER1 VALUES (12, ‘BHASKAR’,’CHENNAI’, 400, 2000);

INSERT INTO CUSTOMER1 VALUES (13, ‘CHETHAN’,’BANGALORE’, 200, 2000);

INSERT INTO CUSTOMER1 VALUES (14, ‘MAMATHA’,’BANGALORE’, 400, 3000);


INSERT INTO ORDERS VALUES (50, 5000, ‘04-MAY-17’, 10, 1000); INSERT INTO ORDERS VALUES (51, 450, ‘20-JAN-17’, 10, 2000);

INSERT INTO ORDERS VALUES (52, 1000, ‘24-FEB-17’, 13, 2000);

INSERT INTO ORDERS VALUES (53, 3500, ‘13-APR-17’, 14, 3000);

INSERT INTO ORDERS VALUES (54, 550, ‘09-MAR-17’, 12, 2000);



Queries:

1.	Count the customers with grades above Bangalore’s average.

SELECT GRADE, COUNT (DISTINCT CUSTOMER_ID) FROM CUSTOMER1

GROUP BY GRADE

HAVING GRADE > (SELECT AVG(GRADE) FROM CUSTOMER1

WHERE CITY='BANGALORE');



2.	Find the name and numbers of all salesmen who had more than one customer.

SELECT SALESMAN_ID, NAME FROM SALESMAN A

WHERE 1 < (SELECT COUNT (*)

FROM CUSTOMER1

WHERE SALESMAN_ID=A.SALESMAN_ID);


3.	List all salesmen and indicate those who have and don’t have customers in their cities (Use UNION operation.)

SELECT SALESMAN.SALESMAN_ID, NAME, CUST_NAME, COMMISSION 
FROM SALESMAN s, CUSTOMER c
WHERE s.SALESMANID=c.SALESMAN_ID and s.CITY<>c.CITY



4.	Create a view that finds the salesman who has the customer with the highest order of a day.

CREATE VIEW ELITSALESMAN AS

SELECT B.ORD_DATE, A.SALESMAN_ID, A.NAME FROM SALESMAN A, ORDERS B

WHERE A.SALESMAN_ID = B.SALESMAN_ID

AND B.PURCHASE_AMT=(SELECT MAX (PURCHASE_AMT)

FROM ORDERS C

WHERE C.ORD_DATE = B.ORD_DATE);



5.	Demonstrate the DELETE operation by removing salesman with id 1000. All his orders must also be deleted.

Use ON DELETE CASCADE at the end of foreign key definitions while creating child table orders and then execute the following:

Use ON DELETE SET NULL at the end of foreign key definitions while creating child table customers and then executes the following:

DELETE FROM SALESMAN

WHERE SALESMAN_ID=1000;