Database Concepts (1)

What type of database is characterised by tables related to each other through keys?

• Entity relationship modelling

• Secondary key

• Relational

• Flat file

Answer explanation

Relational databases are characterized by tables related to each other through keys, making them the correct choice in this scenario.

Which key is unique and identifies each record in a table?

• Index

• Foreign key

• Secondary key

• Primary key

Answer explanation

The primary key is unique and identifies each record in a table, making it the correct choice among the options provided.

What is used to establish a link between two tables in a relational database?

• Primary key

• Normalization

• Foreign key

• Indexing

Answer explanation

A foreign key is used to establish a link between two tables in a relational database by referencing the primary key of another table.

Which concept involves reducing data redundancy and improving data integrity?

• Entity relationship modelling

• Secondary key

• Indexing

• Normalisation

Answer explanation

Normalization involves reducing data redundancy by organizing data into tables and improving data integrity by enforcing relationships between tables through foreign keys.

What is the process of optimising data retrieval called?

• Foreign key

• Indexing

• Normalisation

• Secondary key

Answer explanation

Indexing is the process of optimizing data retrieval by creating data structures to quickly locate and access the requested data.

Which operation is used to extract specific columns from a table?

• Join

• Select

• Insert

• Delete

Answer explanation

The correct operation to extract specific columns from a table is 'Select'.

Which of the following best describes the purpose of a primary key in a database?

• To speed up database search and retrieval

• To establish relationships between tables

• To ensure each record in a table is unique

• To store data redundantly to improve integrity

Answer explanation

The purpose of a primary key in a database is to ensure each record in a table is unique.

What mechanism is used to speed up the performance of database queries?

• Normalisation

• Primary key

• Indexing

• Foreign key

Answer explanation

Indexing is used to speed up the performance of database queries by creating data structures that allow for quick lookup of specific values.

Which of the following is NOT a type of SQL join?

• INNER JOIN

• LEFT JOIN

• RIGHT JOIN

• BACK JOIN

Answer explanation

The correct choice is BACK JOIN as it is not a type of SQL join. The other options - INNER JOIN, LEFT JOIN, and RIGHT JOIN are valid types of SQL joins.

Which SQL statement is used to remove rows from a database table?

• REMOVE

• DELETE

• DROP

• TRUNCATE

Answer explanation

The correct SQL statement used to remove rows from a database table is DELETE.