Top Posters
Since Sunday
50
23
23
22
21
20
20
19
19
18
18
18
New Topic  
wrote...
Posts: 189
2 months ago
Describe the reason why it is acceptable to have null foreign key, but it is unacceptable to have a null primary key. Use the concept of entity integrity rule and referential integrity rule in your answer.
Source  Download
Accounting Information Systems
Edition: 14th
Authors:
Read 21 times
1 Reply
Do What Makes You Come Alive
Replies
Answer verified by a subject expert
wrote...
Posts: 196
2 months ago
Sign in or Sign up in seconds to unlock everything.
A primary key cannot uniquely identify a row in a table if it is null (blank). A nonnull primary key ensures that every row in a table represents something and that it can be identified. This is referred to as the entity integrity rule. Foreign keys link rows in one table to rows in another table. This constraint, called the referential integrity rule, ensures database consistency. Foreign keys can contain null values.
1
Related Topics
New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers.
Learn More
Improve Grades
Help Others
Save Time
Accessible 24/7
  294 People Browsing
Your Opinion
Which 'study break' activity do you find most distracting?
Votes: 157

Related Images
 1120
 312
 40

▶️ Video: Central Nervous System Animation

For a complete list of videos, visit our video library