1. For student, require values for name and address.
For advisor, require values for name, phone, and .
For advisor, make values for unique.

2. SQL DDL Example CREATE TABLE student (pid varchar(9),
name varchar(25) NOT NULL,
address varchar(50) NOT NULL,
phone varchar(15),
varchar(25),
PRIMARY KEY (pid));
CREATE TABLE advisor
(emp_id varchar(5) CONSTRAINT pk_adv PRIMARY KEY,
name varchar(25) NOT NULL,
office varchar(25),
phone varchar(6) NOT NULL,
varchar(25) NOT NULL,
UNIQUE ( ));

3. SQL DDL Example CREATE TABLE st_adv
(pid varchar(9) CONTRAINT fk_st REFERENCES student(pid)
ON DELETE CASCADE ON UPDATE CASCADE,
emp_id varchar(5),
PRIMARY KEY (pid, emp_id),
FOREIGN KEY (emp_id) REFERENCES advisor(emp_id)
ON DELETE CASCADE ON UPDATE CASCADE;
CREATE INDEX sid_x ON student(pid);
CREATE INDEX emp_x ON advisor(emp_id);
CREATE INDEX adv_stx ON st_adv(pid, emp_id);