Integrity constraints in DBMS Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are integrity constraints in a database?

Integrity constraints are rules that ensure the accuracy and consistency of data in a database. They prevent invalid data from being entered.

beginner

Name the four main types of integrity constraints.

The four main types are: 1) Entity Integrity, 2) Referential Integrity, 3) Domain Integrity, and 4) User-Defined Integrity.

beginner

What is Entity Integrity?

Entity Integrity ensures that each row in a table has a unique and non-null primary key, so every record can be uniquely identified.

intermediate

Explain Referential Integrity with a real-life example.

Referential Integrity means that a foreign key in one table must match a primary key in another table or be null. For example, a student's course enrollment must refer to an existing course.

beginner

What is Domain Integrity?

Domain Integrity restricts the type, format, or range of values that can be stored in a column, like allowing only dates or positive numbers.

Which constraint ensures that a primary key cannot be null?

A Entity Integrity

B Referential Integrity

C Domain Integrity

D User-Defined Integrity

Entity Integrity requires that primary keys are unique and not null.

What does Referential Integrity enforce?

A Primary keys must be unique

B Data types must be consistent

C Foreign keys must match primary keys or be null

D User permissions on data

Referential Integrity ensures foreign keys refer to existing primary keys or are null.

Which constraint restricts the allowed values in a column?

A Entity Integrity

B Domain Integrity

C Referential Integrity

D User-Defined Integrity

Domain Integrity controls the type and range of data allowed in a column.

User-Defined Integrity constraints are:

A Rules defined by users for specific business needs

B Only related to foreign keys

C Automatically enforced by the database engine

D Standard rules like primary key uniqueness

User-Defined Integrity allows custom rules based on business logic.

What happens if an integrity constraint is violated?

A The database ignores the violation

B The database deletes the entire table

C The database automatically fixes the data

D The database rejects the data operation

Violating an integrity constraint causes the database to reject the operation to keep data consistent.

Describe the four main types of integrity constraints and their purpose.

Think about how each rule helps keep data accurate and consistent.

Explain with an example how Referential Integrity works in a database.

Consider how tables relate to each other in real life.