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# Database MCQ - Database design

11:

If a relation is in BCNF, then it is also in

 A. 1 NF B. 2 NF C. 3 NF D. All of the above Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Mithinga Kumar Boro said: (7:59am on Tuesday 10th April 2018) i want to know why its answer is all of the above. Write your comments here:
12:

Consider the relation given below and ind the maximum normal form applicable to them

1. R(A, B) with productions { A --> B }

2. R(A, B) with productions  { B --> A }

3 R(A, B) with productions {A —> B, B --> A }

4  R(A, B, C) with productions {A -->B, B --> A, AB --> C }

 A. 1, 2 and 3 are in 3NF and 4 is in BCNF B. 1 and 2 are in BCNF and 3 and 4 are in 3NF C. All are in 3NF D. All are in BCNF Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Naeem Ahmad said: (3:45am on Wednesday 17th June 2015) Answer should be A because 4 is not in BCNF.In 4, FDs A-->B and B-->A do not hold property of neither trivial nor super key.A and B are not super key since AB is primary key.FDs are nontrivial FDs. naresh said: (4:14pm on Friday 4th September 2015) if single relation is there then it will be in bcnf so a and b are in bcnf but c and d are in 3nf becoz determinant is not always key or super key. so answer should be b. Prashant said: (5:57am on Friday 1st September 2017) 4 will be in bcnf because the closure of a,b and ab will be {a,b,c} and all will become a key. Write your comments here:
13:

Consider the following

S1: Foreign key allows null values.

S2: Every binary tables is in BCNF

Which of the following is true

 A. Both S1 and S2 are true B. S1 is true C. S2 is true D. None of these Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
14:

Consider the following functional dependencies in a database:

Date_of_Birth —> Age                                   Age —> Eligibility

Name —> Roll_number                              Roll_number -> Name

Course_number ---> Course—> name      Course_number —> Instructor

The relation (Roll_number; Name; Date_of birth, Age)  is

 A. in second normal form but not in third normal form B. in third normal form but not in BCNF C. in BCNF D. in none of the above Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:
15:

The relation scheme student performance (name, courseNo, rollNo, grade) has the following functional dependencies: