Computer Science - IT MCQs
Topic Notes: Computer Science - IT
<p>MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.</p>
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
161
What does an "Update Query" do?
Answer:
It modifies the data in existing records within a table
An Update Query is used for bulk changes. For example, you could use one to increase the price of all products in a certain category by 10%.
162
Which type of query makes changes to the data in your tables?
Answer:
Action Query
Action Queries are used to modify data. There are four types: Make-Table, Append, Update, and Delete queries.
163
To filter records in a query to show only customers from "London", you would type "London" in the _________ row for the City field.
Answer:
Criteria
The Criteria row in the design grid is where you specify the conditions that records must meet to be included in the query results.
164
In the Query Design View, the top pane shows _________, and the bottom pane (the design grid) shows __________.
Answer:
The tables used in the query, the fields and criteria for the query
The top pane is where you add the tables you want to get data from. The bottom grid is where you build the query by adding fields, setting sort orders, and entering criteria.
165
What is the main purpose of a "Select Query"?
Answer:
To retrieve and view data from one or more tables
A Select Query is the most common type of query. It is used to select a specific subset of data based on criteria you define, without changing the underlying data.
166
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
167
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.
168
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).
169
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.
170
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.