CONSTRAINTS CHAPTER-4 EXAM QUESTIONS
AND CORRECT ANSWERS
D. None of the above statements is correct - CORRECT ANSWERS Which of the following
statements is correct?
A. A PRIMARY KEY constraint allows NULL values in the primary key column(s)
B. You can enable a dropped constraint if you need it in the future
C. Every table must have at least one PRIMARY KEY constraint, or Oracle 11g doesn't allow the
table to be created
D. None of the above statements is correct
A. PRIMARY KEYS - CORRECT ANSWERS Which of the following is not a valid constraint
type?
A. PRIMARY KEYS
B. UNIQUE
C. CHECK
D. FOREIGN KEY
C. ALTER TABLE books ADD CONSTRAINT books_pubid_nn NOT NULL (pubid); - CORRECT
ANSWERS Which of the following SQL statements is invalid and returns an error message?
A. ALTER TABLE books ADD CONSTRAINT books_pubid_uk UNIQUE (pubid);
B. ALTER TABLE books ADD CONSTRAINT books_pubid_pk Primary Key (pubid);
C. ALTER TABLE books ADD CONSTRAINT books_pubid_nn NOT NULL (pubid);
D. ALTER TABLE books ADD CONSTRAINT books_pubid_fk FOREIGN KEY (pubid) REFERENCES
publisher (pubid);
E. All of the above statements are invalid
, A. 1 - CORRECT ANSWERS What are the maximum number of PRIMARY KEY constraints
allowed for a table?
A. 1
B. 2
C. 30
D. 255
E. None of the above commands is valid - CORRECT ANSWERS Which of the following is a
valid SQL command?
A. ALTER TABLE books ADD CONSTRAINT UNIQUE (pubid);
B. ALTER TABLE books ADD CONSTRAINT PRIMARY KEY (pubid);
C. ALTER TABLE books MODIFY (pubid CONSTRAINT NOT NULL);
D. ALTER TABLE books ADD FOREIGN KEY CONSTRAINT (pubid) REFERENCES publisher (pubid);
E. None of the above commands is valid
A. 0 - CORRECT ANSWERS How many NOT NULL constraints can be created at the table
level by using the CREATE TABLE command?
A. 0
B. 1
C. 12
D. 30
E. 255
C. the child table in a parent-child relationship - CORRECT ANSWERS The FOREIGN KEY
constraint should be added to which table?
A. the table representing the "one" side of a one-to-many relationship
B. the parent table in a parent-child relationship
AND CORRECT ANSWERS
D. None of the above statements is correct - CORRECT ANSWERS Which of the following
statements is correct?
A. A PRIMARY KEY constraint allows NULL values in the primary key column(s)
B. You can enable a dropped constraint if you need it in the future
C. Every table must have at least one PRIMARY KEY constraint, or Oracle 11g doesn't allow the
table to be created
D. None of the above statements is correct
A. PRIMARY KEYS - CORRECT ANSWERS Which of the following is not a valid constraint
type?
A. PRIMARY KEYS
B. UNIQUE
C. CHECK
D. FOREIGN KEY
C. ALTER TABLE books ADD CONSTRAINT books_pubid_nn NOT NULL (pubid); - CORRECT
ANSWERS Which of the following SQL statements is invalid and returns an error message?
A. ALTER TABLE books ADD CONSTRAINT books_pubid_uk UNIQUE (pubid);
B. ALTER TABLE books ADD CONSTRAINT books_pubid_pk Primary Key (pubid);
C. ALTER TABLE books ADD CONSTRAINT books_pubid_nn NOT NULL (pubid);
D. ALTER TABLE books ADD CONSTRAINT books_pubid_fk FOREIGN KEY (pubid) REFERENCES
publisher (pubid);
E. All of the above statements are invalid
, A. 1 - CORRECT ANSWERS What are the maximum number of PRIMARY KEY constraints
allowed for a table?
A. 1
B. 2
C. 30
D. 255
E. None of the above commands is valid - CORRECT ANSWERS Which of the following is a
valid SQL command?
A. ALTER TABLE books ADD CONSTRAINT UNIQUE (pubid);
B. ALTER TABLE books ADD CONSTRAINT PRIMARY KEY (pubid);
C. ALTER TABLE books MODIFY (pubid CONSTRAINT NOT NULL);
D. ALTER TABLE books ADD FOREIGN KEY CONSTRAINT (pubid) REFERENCES publisher (pubid);
E. None of the above commands is valid
A. 0 - CORRECT ANSWERS How many NOT NULL constraints can be created at the table
level by using the CREATE TABLE command?
A. 0
B. 1
C. 12
D. 30
E. 255
C. the child table in a parent-child relationship - CORRECT ANSWERS The FOREIGN KEY
constraint should be added to which table?
A. the table representing the "one" side of a one-to-many relationship
B. the parent table in a parent-child relationship
