This topic contains a solution. Click here to go to the answer
« previous next »

Author Question: How is a composite attribute of an entity mapped into a relation? What will be an ideal ... (Read 14 times)

bcretired

  • Hero Member
  • *****
  • Posts: 525
on: Jul 7, 2018
How is a composite attribute of an entity mapped into a relation?
 
  What will be an ideal response?

Question 2

What is a primary key?
 
  What will be an ideal response?


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

31809pancho

  • Sr. Member
  • ****
  • Posts: 317
Reply #1 on: Jul 7, 2018
Answer to Question 1

If an entity contains composite attributes, each component of the composite attribute is mapped as a column of a relation, while the composite attribute itself does not appear in the mapped relation.

Answer to Question 2

Primary key is a column (or a set of columns) whose value is unique for each row. Primary keys cannot have null values. If there are multiple columns (or sets of columns) that have unique values in each row, one of them is designated as a primary key. Each relation must have a primary key.


bcretired

  • Member
  • Posts: 525
Reply 2 on: Jul 7, 2018
YES! Correct, THANKS for helping me on my review

isabelt_18

  • Member
  • Posts: 342
Reply 3 on: Yesterday
Excellent

« previous next »
 

Did you know?

Carbamazepine can interfere with the results of home pregnancy tests. If you are taking carbamazepine, do not try to test for pregnancy at home.

Did you know?

Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).

Did you know?

The largest baby ever born weighed more than 23 pounds but died just 11 hours after his birth in 1879. The largest surviving baby was born in October 2009 in Sumatra, Indonesia, and weighed an astounding 19.2 pounds at birth.

Did you know?

Pink eye is a term that refers to conjunctivitis, which is inflammation of the thin, clear membrane (conjunctiva) over the white part of the eye (sclera). It may be triggered by a virus, bacteria, or foreign body in the eye. Antibiotic eye drops alleviate bacterial conjunctivitis, and antihistamine allergy pills or eye drops help control allergic conjunctivitis symptoms.

Did you know?

When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).

Relation between form, particular objects, and images in Plato’s Line. Relation between form, particular objects, and images in Plato’s Line.
The hypothalamus and pituitary glands and their relation to the brain. The hypothalamus and pituitary glands and their relation to the brain.
What are examples of ideal forms? What are examples of ideal forms?
The course of EEG stages during a typical night’s sleep and the relation of emergent stage 1 EEG ... The course of EEG stages during a typical night’s sleep and the relation of emergent stage 1 EEG ...
Posterior view of midbrain in relation to brain stem Posterior view of midbrain in relation to brain stem
Split-brain patients were shown composite photographs Split-brain patients were shown composite photographs
Video: Vascular tissues in a corn stem and a buttercup root

For a complete list of videos, visit our video library