ALTER TABLE salesman
ADD CONSTRAINT P_K PRIMARY KEY(sid)

CREATE TABLE customer(
    cid int,
    cname varchar(20),
   ccity varchar(10),
cgrade int,
    sid int,
     PRIMARY KEY(cid),      
    FOREIGN KEY (sid) REFERENCES salesman(sid)
    );

CREATE TABLE morder(
  ono int,
   purchase_amount int,
orderdate Date,
    sid int,
    cid int,
     PRIMARY KEY(ono),      
    FOREIGN KEY (sid) REFERENCES salesman(sid),
       FOREIGN KEY (cid) REFERENCES customer(cid)
    );
INSERT INTO salesman VALUES(1,'AB','chittagong',0.10,10000);
INSERT INTO salesman VALUES(2,'AC','barishal',0.12,20000);
INSERT INTO salesman VALUES(3,'AD','chittagong',0.19,30000);
INSERT INTO salesman VALUES(4,'AE','dhaka',0.20,40000);

INSERT INTO customer VALUES(5,'z','dhaka','A',1);
INSERT INTO customer VALUES(6,'y','chittagong','B',2);
INSERT INTO customer VALUES(7,'x','barishal','C',3);
INSERT INTO customer VALUES(8,'w','khulna','D',4);

INSERT INTO morder VALUES(1,1000,'27-07-23',1,5);
INSERT INTO morder VALUES(2,2000,'26-07-23',2,6);
INSERT INTO morder VALUES(3,3000,'29-07-23',3,7);
INSERT INTO morder VALUES(4,4000,'25-07-23',4,8);

SELECT sname, scity
FROM salesman
WHERE scity = 'chittagong';