What is the difference between a primary key and a foreign key in a relational database management system (RDBMS)?

Understanding the difference between the primary key and foreign key in a relational database management system (RDBMS)

The primary key and foreign key are fundamental concepts in a relational database system. Let's delve into their distinctions:

Primary Key:

A primary key is a unique identifier for each record in a table. It ensures that each row in a table is distinctly identified. It enforces entity integrity and guarantees that no duplicate data is present in the column defined as the primary key. The primary key uniquely identifies a record in the table and is a critical component for data manipulation and retrieval.

Foreign Key:

A foreign key establishes a link between two tables in a database. It is a field or a combination of fields in a table that matches the primary key in another table. The foreign key maintains referential integrity within the database by ensuring that the value in the foreign key column exists as a primary key value in another table. It allows for the establishment of relationships between tables, enabling data consistency and integrity across the database.

Key Differences:

• The primary key uniquely identifies each record in a table, while the foreign key links tables together.
• The primary key ensures data uniqueness within a table, whereas the foreign key enforces data integrity between tables.
• Primary keys are defined on a column in a single table, while foreign keys establish relationships between tables.

Understanding the disparities between the primary key and foreign key is crucial for building efficient and well-structured relational databases.

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