Computer Science/IT MCQs
Topic Notes: Computer Science/IT
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
4601
What is the function of `TRUNCATE TABLE`?
Answer:
To delete all data from a table quickly.
`TRUNCATE TABLE` is a DDL command that removes all rows from a table, but the table structure, columns, constraints, and indexes remain. It is generally much faster than a `DELETE` statement with no `WHERE` clause.
4602
The relationship between a `Student` and the `Courses` they are enrolled in is an example of a:
Answer:
Many-to-many relationship
One student can enroll in many courses, and one course can be taken by many students. Therefore, the relationship is many-to-many (M:N).
4603
A collection of concepts used to describe the structure of a database, including data types, relationships, and constraints, is a:
Answer:
Data Model
A data model provides the theoretical framework for a database. It defines how data is connected to each other, how it is processed, and how it is stored within the system. Examples include the relational, hierarchical, and network models.
4604
Can a foreign key column contain NULL values?
Answer:
Yes, if the column is not also defined with a NOT NULL constraint.
A foreign key can contain NULL values. This typically means that the record does not have a relationship with the parent table. For example, an 'Employee' record might have a NULL value for 'ManagerID' if that employee is the CEO.
4605
Boyce-Codd Normal Form (BCNF) is considered a stricter version of which normal form?
Answer:
3NF
BCNF is an extension of Third Normal Form and is slightly stronger. While a table in BCNF is always in 3NF, a table in 3NF is not necessarily in BCNF. BCNF handles certain rare anomalies that 3NF does not.
4606
Which of the following is a disadvantage of file processing systems that DBMS aims to solve?
Answer:
Data isolation
In traditional file processing systems, data is often stored in separate, isolated files, making it difficult to access and share data across different applications. A DBMS solves this by providing a centralized repository of data that can be accessed by multiple users and applications simultaneously.
4607
When changes to data occur in multiple lists and not all are updated, it causes:
Answer:
Data inconsistency
Data inconsistency occurs when the same data exists in different formats in multiple tables, leading to unreliable information.
4608
Which join returns all records when there is a match in either the left or the right table?
Answer:
FULL OUTER JOIN
A `FULL OUTER JOIN` combines the results of both left and right outer joins. It returns all rows from both tables, with NULLs in places where the join condition is not met.
4609
Which of the following best describes 'data independence'?
Answer:
The separation of data storage from the user's logical view of the data.
Data independence is a key feature of DBMS. It means that the application programs are insulated from changes in the way the data is structured and stored, allowing the database's physical structure to change without affecting the application's view of it.
4610
From a table's set of candidate keys, one is chosen by the database designer to be the main identifier for the table. This chosen key is the:
Answer:
Primary Key
A table may have several potential keys (candidate keys) that could uniquely identify its rows. The database designer selects one of these candidate keys to be the primary key, which will be the main means of identifying records.