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
341
A data anomaly caused by data redundancy where updating a value requires changing it in multiple places is a(n):
Answer:
Update anomaly
An update anomaly occurs when a single piece of real-world information is stored in multiple rows. If this information is updated, all corresponding rows must be changed. Failing to update all rows leads to data inconsistency.
342
The `COMMIT` and `ROLLBACK` commands, which manage database transactions, are part of which SQL sub-language?
Answer:
TCL
TCL stands for Transaction Control Language. These commands are used to manage transactions in the database, ensuring they are completed successfully (`COMMIT`) or undone (`ROLLBACK`).
343
What is the primary purpose of the `GROUP BY` clause in a `SELECT` statement?
Answer:
To arrange rows into groups based on the values in one or more columns.
The `GROUP BY` clause is often used with aggregate functions (like `COUNT`, `MAX`, `SUM`) to group the result-set by one or more columns, allowing you to perform calculations on each group.
344
What is the highest level in the hierarchy of data organization?
Answer:
Data base
The database represents the highest level in the data hierarchy. It is a comprehensive collection that logically contains all the related files, which in turn contain records, fields, and so on.
345
Which of the following is NOT a relational DBMS?
Answer:
Reflex
While dBase IV, 4th Dimension, and FoxPro are all examples of relational database management systems, Reflex was an early flat-file database manager and not a relational one.
346
An ad hoc query is best described as what?
Answer:
Spur-of-the-moment question
Ad hoc queries are created on demand to answer a specific, often one-time question, without being pre-defined in the system.
347
A key used for data retrieval purposes that is not a primary or candidate key is often called a:
Answer:
Secondary key
A secondary key is an attribute or combination of attributes that is used for indexing and retrieval. Unlike a primary key, its values do not have to be unique. For example, `LastName` could be a secondary key for efficient searching.
348
Report generators in DBMS are utilized to:
Answer:
Both b and c
Report generators are powerful tools within a DBMS that are specifically designed to retrieve requested information from the database and present it in a formatted, readable report, which effectively answers user queries for data.
349
Referential integrity is a rule that the database enforces to ensure relationships between tables remain consistent. It is typically enforced using a:
Answer:
Foreign Key
Referential integrity is the core concept behind foreign keys. It ensures that a value cannot be entered into a foreign key column unless it matches a value in the referenced primary key column of the parent table.
350
Which type of database stores data in two-dimensional tables?
Answer:
Relational
Relational databases organize data into tables, which consist of rows and columns, allowing for flexible relationships between different data sets.