Differences between Primary Key and Foreign Key in a Relational Database System

Primary Key:

• A Primary Key uniquely identifies each record in a table.
• It must have a unique value and cannot be null.
• There can be only one Primary Key in a table.

Foreign Key:

• A Foreign Key establishes a relationship between two tables.
• It refers to the Primary Key of another table to maintain referential integrity.
• It can have duplicate values and can be null.

Ensuring Data Integrity

Primary Keys and Foreign Keys are used to maintain data integrity in a relational database system by:

• Enforcing entity integrity by ensuring each record has a unique identifier.
• Implementing referential integrity to maintain relationships between tables.
• Preventing orphan records by requiring foreign keys to reference valid primary key values.

Differences Between Primary Key and Foreign Key in a Relational Database System

Focus Keyword: data integrity

In a relational database system, a primary key uniquely identifies each record in a table and ensures each record is unique. It serves as the main point of reference for establishing relationships between tables. The primary key constraint enforces the uniqueness and non-null constraint on the column or set of columns.

On the other hand, a foreign key establishes a relationship between two tables, where the foreign key in one table is linked to the primary key in another table. This relationship maintains referential integrity between the tables, ensuring that data remains consistent and connected.

Utilizing primary and foreign keys in a database system plays a critical role in ensuring data integrity. By defining primary keys, each record is uniquely identified, preventing duplicate entries. Foreign keys then link related tables, enforcing referential integrity by maintaining the relationships between them. This helps to avoid orphaned records and ensures that the data remains consistent and accurate throughout the database.

Overall, the combination of primary and foreign keys in a relational database system helps to maintain data integrity by enforcing uniqueness, relationships, and consistency in the stored data.