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Database management system

Database management system - questions and solutions

Question:-
Option (A)
{A -> BC, E -> C, D -> AH, AH -> B}
Option (B)
{A -> B, E -> C, D -> EH, AH -> D}
Option (C)
{A -> BC, E -> C, D -> AEH, AH -> D}
Option (D)
{A -> BC, E -> C, D -> H, AH -> BD}
Correct Option:
C
Question:-
Option (A)
Relational algebra and relational calculus are both procedural query language
Option (B)
Relational algebra is procedural query language and relational calculus is a non procedural
Option (C)
Relational algebra and relational calculus are both non procedural query language
Option (D)
Relational algebra is a non procedural query language and relational calculus is a procedural query language
Correct Option:
B
Question Solution:
Relational algebra is a theoretical language. It defines relational operators that are used to perform various operations on relations. The relational algebra helps to learn SQL because the syntax of SQL statements are similar to syntax of relational algebra expression. It is a procedural language. Relational calculus is a non-procedural relational data manipulation language in which user specifies what data should be retrieved, but not how to retrieve the data.
Question:-
Option (A)
An alternate key is a candidate key that is not a primary key
Option (B)
An alternate key is a primary key that is not a candidate key
Option (C)
An alternate key is a candidate key that is also a primary key
Option (D)
None of the above
Correct Option:
A
Question Solution:
An alternate key is one of the candidate key that is not a primary key.
Question:-
Option (A)
1 and 4
Option (B)
2, 3 and 4
Option (C)
1, 2 and 3
Option (D)
All 1, 2, 3 and 4 can be solved
Correct Option:
C
Question Solution:
The concept of locking can be used to solve the problem of lost update, uncommitted dependency and prevents inconsistency among data but it is not capable of preventing the deadlock always.
Hence (c) is the correct option
Question:-
Option (A)
1, 2 only
Option (B)
1 only
Option (C)
1, 3 only
Option (D)
1, 2 and 3
Correct Option:
D
Question Solution:
4 NF is stronger normal form than BCNF as it prevents tables from containing nontrivial mutlivalued, dependencies (MVDs) and hence data redundancy. All the statements are true.
Question:-
Option (A)
Employee (EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName))
Option (B)
Supervision (EmpID,BithDate, Salary, Name(FirstName, MiddleName, LastName), EmpId)
Option (C)
Supervisor (SupervisorID, BirthDate, Salary, Name(FirstName, MiddleName, LastName), EmpID), {EmpID})
Option (D)
Employee (EmpID, BirthDate, Salary, Name(FirstName, MiddleName, LastName), SupervisorID)
Correct Option:
D
Question Solution:
The given ERD shows the self recursively relationship among Employees.
1 is supervisor 2 is supervisee.
The possible relation is
Employee (Emp Id, Birthdate, Salary, Name (First Name, Middle Name, Last Name), Supervisor Id)