Database design best practices in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is normalization in database design?

Normalization is the process of organizing data to reduce duplication and improve data integrity by dividing tables and defining relationships.

beginner

Why should you use primary keys in tables?

Primary keys uniquely identify each record in a table, ensuring each row can be referenced and preventing duplicate records.

beginner

What is the purpose of foreign keys?

Foreign keys link records between tables, enforcing referential integrity by ensuring related data exists in the referenced table.

beginner

Why is it important to avoid redundant data in a database?

Avoiding redundant data saves storage space, reduces errors, and makes updates easier because data is stored in one place only.

intermediate

What does indexing do in a database?

Indexing speeds up data retrieval by creating a quick lookup structure, similar to an index in a book.

Which of the following best describes a primary key?

A A unique identifier for each record in a table

B A field that stores large text data

C A key used to encrypt data

D A field that can contain duplicate values

A primary key uniquely identifies each record and cannot have duplicates.

What is the main goal of normalization?

A To organize data to reduce redundancy

B To store data in one large table

C To speed up queries by adding indexes

D To increase data duplication

Normalization organizes data to reduce redundancy and improve integrity.

Which key enforces a relationship between two tables?

A Primary key

B Foreign key

C Candidate key

D Composite key

Foreign keys link tables and enforce referential integrity.

Why should you avoid storing the same data in multiple places?

A It makes the database faster

B It helps with backup

C It causes data inconsistency and wastes space

D It improves security

Storing duplicate data wastes space and can cause inconsistencies.

What does an index do in a database?

A Deletes old data automatically

B Encrypts data for security

C Stores backup copies

D Speeds up data retrieval

Indexes speed up searching by creating a quick lookup.

Explain the importance of primary keys and foreign keys in database design.

Think about how tables connect and keep data consistent.

Describe what normalization is and why it is used in databases.

Consider how to keep data clean and avoid repetition.