B CompE Bachelor of Computer Engineering Database Management Systems 2

Question 1

Which indexing structure is most commonly used in relational databases for primary keys?

Accepted Answer

B-Tree Index

Answer

B-Tree indexes are the default in most relational databases because they support both equality and range queries efficiently.

Question 2

What is a deadlock in a database system?

Accepted Answer

Two transactions wait indefinitely for each other to release locks

Answer

A deadlock occurs when two or more transactions each hold a lock the other needs, creating a circular wait that prevents progress.

Question 3

Which relational algebra operation combines tuples from two relations where a condition is met?

Accepted Answer

Join

Answer

The Join operation in relational algebra combines rows from two relations based on a matching condition between their attributes.

Question 4

What is the purpose of a database view?

Accepted Answer

Provide a virtual table based on the result of a stored query

Answer

A database view is a stored query that appears as a virtual table, simplifying complex queries and restricting data access.

Question 5

Which SQL aggregate function returns the total number of rows in a result set?

Accepted Answer

COUNT()

Answer

COUNT() returns the number of rows that match the specified criteria, counting non-NULL values when a column is specified.

B CompE Bachelor of Computer Engineering Practice Test