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
91
The field on the "many" side of a one-to-many relationship (the foreign key) _________ have to be unique.
Answer:
Does not
In fact, the foreign key field is expected to have duplicate values. For instance, in an Orders table, the same `CustomerID` will appear many times (once for each order that customer placed). ### Queries and SQL Basics in Access
92
A "lookup list" is often populated by the values from a field in another table. This is an application of:
Answer:
Table relationships and foreign keys
Creating a lookup field that pulls data from another table (e.g., a dropdown list of all customer names) is a practical use of a table relationship, ensuring you can only select valid customers.
93
Can a table have more than one foreign key?
Answer:
Yes, a table can have multiple foreign keys linking to multiple different tables
Absolutely. For example, an "Orders" table might have a foreign key for `CustomerID` (linking to Customers) and another for `EmployeeID` (linking to the salesperson in the Employees table).
94
If a book can be written by multiple authors, and an author can write multiple books, the relationship between "Books" and "Authors" is:
Answer:
Many-to-Many
This is a classic example of a many-to-many relationship that would require a junction table (e.g., "BookAuthors") containing `BookID` and `AuthorID` to link the two main tables.
95
The process of organizing data into tables and establishing relationships between them is called:
Answer:
Normalization
Normalization is the formal process of designing a database to reduce redundancy and improve data integrity by dividing larger tables into smaller, well-structured tables and defining relationships between them.
96
In the Relationships window, how do you delete a relationship?
Answer:
Right-click the relationship line and choose "Delete"
You can manage relationships by right-clicking the line that connects the tables to either edit its properties or remove it entirely.
97
A well-designed relational database minimizes:
Answer:
Data redundancy
The main goal of normalization and creating relationships is to store each piece of information only once. This saves space and, more importantly, improves data consistency and accuracy.
98
Which data type is ideal for a primary key that has no real-world meaning but just needs to be unique?
Answer:
AutoNumber
The AutoNumber data type is perfect for creating "surrogate" primary keys. It automatically generates a new, unique number for each record, saving the user from having to invent one.
99
What happens if you try to enter a value into a foreign key field that does not exist in the related primary key field (with referential integrity enforced)?
Answer:
Access will display an error message and prevent you from adding the record
This is the core function of referential integrity. It prevents the creation of orphan records by ensuring that the foreign key value always points to a valid, existing record in the primary table.
100
A "Candidate Key" is:
Answer:
A field or set of fields that could potentially be used as the primary key
A table might have several fields that are unique (e.g., StudentID, SocialSecurityNumber). Any of these could serve as the primary key. They are all considered candidate keys until one is chosen as the primary key.