Foreign key is a field in a relational database table that establishes a relationship between two tables based on the values of one or more fields in each table.
Foreign key Rule
- Foreign key in one table refers to the primary key in another table.
- The table containing the foreign key is called the referencing table or child table.
- The table with the primary key is called the referenced table or parent table.
- In the context of foreign keys, referential integrity means that the values in the foreign key match the values in the primary key.
Benefits of Foreign Keys
- Data Integrity
- Foreign keys help to enforce referential integrity, which ensures that data is consistent and accurate across related tables. Foreign keys ensure that data entered into a table matches the primary key of another table, preventing the creation of invalid records.
- Query Performance Increases
- Foreign keys can improve the query performance by allowing the database to efficiently join tables. This can help to reduce the amount of data that needs to be processed during execution of query.
- Simplified Database Design
- This is done by reducing the need for redundant data in multiple tables. Instead of duplicating data in multiple tables, a foreign key can be used to reference a single primary key in another table.
- Data Maintenance is easy
- Foreign keys can make it easier to maintain data in a database by providing a clear and structured way to manage relationships between tables. This can make it easier to update and modify data without introducing inconsistencies or errors.
- Data Analysis may be better
- Foreign keys can improve data analysis by making it easier to analyze data across related tables. By using foreign keys to link tables together, analysts can perform more complex queries and generate more accurate reports.
