The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
+15 votes

Which normal form is considered adequate for normal relational database design?

  1. $2NF$
  2. $5NF$
  3. $4NF$
  4. $3NF$
asked in Databases by Veteran (59.7k points)
edited by | 1.1k views

4 Answers

+31 votes
Best answer
because we can always have a $3NF$ decomposition which is dependency preserving and lossless (not possible for any higher forms).
answered by Veteran (55.6k points)
edited by
till 3NF both lossless join and dependency preserving hold .for BCNF lossless join hold but dependency preserving not guaranteed.for higher than BCNF even lossless join also not guaranteed along with dependecy preserving
+14 votes
Answer: D
3NF will be adequate for normal relational database design since 3NF tables are free of insertion, update, and deletion anomalies.
answered by Boss (34k points)

Rajarshi Sarkar can you please explain - 3NF tables are free of insertion, update, and deletion anomalies.

+11 votes
3 NF cause it ensures both lossless and dependency preserving ..In BCNF DP is not always possible although it is more strict than 3NF..
answered by Active (1.9k points)
0 votes
Ans: D
answered by Loyal (7.6k points)
But why not BCNF, sure 3NF is dependency preserving. BCNF is less redundant compare to 3NF. Size of DB is an concern.
3NF is always lossless and dependency preserving but BCNF is always lossless only. Dependency preserving is not guaranteed in BCNF
Why we want the dependency preserving property in our database ,can anyone explain it ?

iknow that bcnf is less redundant then 3nf that's why i am thinking that bcnf should be optimal choice

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true

44,149 questions
49,639 answers
65,807 users