SQL Contraints and Triggers

Question 1

What does the keyword UNIQUE do?

Answer 1

Declares keys

Question 2

What do the keywords NOT NULL do?

Answer 2

Disallows null values

Question 3

What do the keywords PRIMARY KEY do?

Answer 3

It is a combination of key + not null

Question 4

What do the keywords FOREIGN KEY do?

Answer 4

References attributes in other tables

Question 5

_____ values are ignored when checking constraints

Answer 5

NULL

Question 6

_____ uniquely identify the tuples of a relation

Answer 6

KEYS

Question 7

How do you declare a key with more than one attribute?

Answer 7

UNIQUE (p1, p2)

Question 8

What are 3 ways to handle a deletion of an property referred to by a foreign key?

Answer 8

1. Reject
2. Propogate
3. Set to NULL

Question 9

A _______ rejects updates/insertions of the condition is false

Answer 9

CHECK

Question 10

A _______ is a datatype with optional constraints

Answer 10

DOMAIN

Question 11

An _______ is a CHECK constraint not bound to a specific table

Answer 11

ASSERT

Question 12

What are 3 components of a trigger?

Answer 12

• Event (update, delete, etc)
• Condition
• Action (make queries, examine)

Question 13

TRIGGERS are processed in a _______ order

Answer 13

arbitrary

Question 14

A collection of TRIGGERS can have ______________ effects

Answer 14

unpredictable