All Categories MCQs
Topic Notes: All Categories
General Description
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
321
The function of a database is:
Answer:
To collect and organize input data
The primary and most fundamental function of a database is to act as a structured repository. It is designed to systematically collect input data and organize it in a way that allows for efficient storage, retrieval, and management.
322
Which of the following changes may fail when modifying a database column?
Answer:
Changing a column data type from char to date
This change may fail if the existing character data in the column cannot be validly converted into the date format.
323
What is a composite key?
Answer:
A key that is composed of two or more columns.
A composite key is a primary key that consists of two or more columns. The combination of these columns' values must be unique for each record in the table, even though the individual column values may not be unique.
324
A transitive dependency exists when a non-key attribute is functionally dependent on:
Answer:
Another non-key attribute.
A transitive dependency is an indirect relationship between attributes. If A -> B and B -> C, then there is a transitive dependency C -> A via B, where A is the primary key and B and C are non-key attributes. 3NF aims to remove this.
325
Can a primary key column contain NULL values?
Answer:
No, a primary key must not contain NULL values.
A primary key constraint is a combination of a `NOT NULL` constraint and a `UNIQUE` constraint. Therefore, it is a strict rule that a primary key column cannot have any NULL values.
326
An attribute in one table that is a primary key in another table is a:
Answer:
Foreign Key
This is the definition of a foreign key. It creates a referential link between the two tables.
327
What do you create when you want to ask the database for specific information?
Answer:
Query
A query is a formal request to a database to retrieve, add, modify, or delete data based on specified criteria.
328
Which is not true for the traditional information processing approach?
Answer:
There is common sharing of data among the various applications
Traditional information processing systems were file-oriented and created data silos, where each application had its own separate files. This made common data sharing between different applications very difficult, unlike the integrated approach of a DBMS.
329
A command that lets you change one or more fields in a record is:
Answer:
Modify
The modify command, known as `UPDATE` in standard SQL, is the specific DML command used to alter or change the data within one or more existing records in a table.
330
When you link one database table to another, what are you creating?
Answer:
Relationships
Linking tables via keys like primary and foreign keys establishes relationships, which allows data to be efficiently combined and retrieved across multiple tables.