Databases: Pre-Unit Knowledge Check

What is the main purpose of a database?

• To store, manipulate, and retrieve data

• To manage operating systems

• To display multimedia

• To design web pages

Answer explanation

The main purpose of a database is to store, manipulate, and retrieve data efficiently. This functionality is essential for managing large amounts of information, making the first choice the correct answer.

What is a relational database?

• A type of database that stores data in non-relational tables

• A type of database where data is stored in interconnected tables

• A database only used for social networks

• A system where data is stored as one long file

Answer explanation

A relational database organizes data in interconnected tables, allowing for efficient data retrieval and management. This distinguishes it from non-relational databases, which do not use this table-based structure.

Which of the following is NOT an example of a relational database management system (RDBMS)?

• Microsoft Access

• Oracle Database

• SQL Server

• Microsoft Excel

Answer explanation

Microsoft Excel is a spreadsheet application, not a relational database management system (RDBMS). In contrast, Microsoft Access, Oracle Database, and SQL Server are all examples of RDBMS that manage data in structured formats.

What is the purpose of normalisation in a database?

• To reduce data redundancy and improve data integrity

• To increase data redundancy for faster access

• To allow multiple users to access the database simultaneously

• To enhance the graphical interface of the database

Answer explanation

The purpose of normalization in a database is to reduce data redundancy and improve data integrity. This process organizes data efficiently, ensuring that each piece of information is stored only once, minimizing duplication.

Which of the following is a benefit of using a relational database?

• A. Increased data redundancy

• B. Easier management of relationships between data sets

• C. Limited scalability

• D. Data is stored randomly

Answer explanation

B is correct because relational databases are designed to manage relationships between data sets efficiently, allowing for easier data retrieval and organization compared to other database types.

What is a primary key in a database table?

• A. A unique identifier for each record

• B. A key used to encrypt data

• C. The main menu key in a database system

• D. A key that defines foreign relationships

Answer explanation

A primary key is a unique identifier for each record in a database table, ensuring that no two records can have the same key value. This is essential for maintaining data integrity and enabling efficient data retrieval.

In a relational database, what does an "entity" refer to?

• A. A row of data

• B. A column in a table

• C. A real-world object or concept represented by data

• D. A type of relationship between data sets

Answer explanation

In a relational database, an 'entity' refers to a real-world object or concept represented by data, making option C the correct choice. Options A and B refer to data structure components, while D describes relationships, not entities.

Which SQL command is used to retrieve data from a database?

• A. SELECT

• B. INSERT

• C. UPDATE

• D. DELETE

Answer explanation

The SQL command used to retrieve data from a database is A. SELECT. This command allows users to specify which data they want to see, making it essential for querying databases.

What is a foreign key in a relational database?

Answer explanation

A foreign key in a relational database is a field (or collection of fields) that establishes a link between data in two tables. It refers to the primary key in another table, ensuring referential integrity.

Which of the following operations is a typical function of a relational database?

• Storing images

• Writing software code

• Sorting and filtering data

• Designing user interfaces

Answer explanation

Sorting and filtering data are core functions of a relational database, allowing users to organize and retrieve specific information efficiently. The other options do not represent typical database operations.