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
101
When Access displays a "Subdatasheet" (a small '+' sign next to a record), it is showing:
Answer:
Records from a related table based on a one-to-many relationship
The subdatasheet is a direct visual representation of the relationship. Clicking the '+' next to a customer record will show you all the orders for that customer directly within the customer table's datasheet view.
102
A "self-join" or "self-referencing relationship" is when:
Answer:
A table is joined to itself
This is used to model hierarchical data within a single table. For example, in an "Employees" table, you could have a `SupervisorID` field that is a foreign key linking to the `EmployeeID` (primary key) of the same table.
103
In a relationship between a "Departments" table and an "Employees" table, which is the "one" side?
Answer:
Departments
One department can have many employees. Therefore, "Departments" is the "one" side of the relationship.
104
Can a primary key field contain a Null (empty) value?
Answer:
No, a primary key must always have a value
The fundamental rule of a primary key is that it must uniquely identify a record. A Null value is not unique and therefore is not allowed. Access automatically enforces this rule.
105
What is the primary benefit of creating relationships between tables?
Answer:
It reduces data redundancy and improves data integrity
Instead of typing a customer's full name and address on every single order, you store it once in the Customers table and simply link to it. This saves space and ensures that if the customer's address changes, you only need to update it in one place.
106
An example of a many-to-many relationship would be between which two tables?
Answer:
Students and Classes
One student can enroll in many classes, and one class can have many students. This requires a junction table (e.g., an "Enrollment" table) to link them.
107
To establish a relationship, the linked fields (primary and foreign keys) must:
Answer:
Have the same data type
This is a requirement for creating a relationship. You cannot link a Number field to a Text field. While it's good practice for them to have the same name, it is not strictly required.
108
The "Cascade Delete Related Records" option means that:
Answer:
If you delete a primary key record, Access will automatically delete all related records in the "many" table.
This is a powerful but potentially dangerous option. For example, if you turn this on and delete a customer, all of their orders will also be permanently deleted.
109
The "Cascade Update Related Fields" option for referential integrity means that:
Answer:
If you update a primary key value, Access will automatically update the matching foreign key values in the related table.
This feature helps maintain data consistency. If a `CustomerID` changes from 101 to 505, this option will automatically find all orders for customer 101 and change their `CustomerID` to 505.
110
What is a "One-to-One" relationship?
Answer:
Each record in one table can have one, and only one, matching record in another table.
This type of relationship is less common. It might be used to split a table with many columns or for security reasons, such as separating employee contact information from sensitive payroll information.