Foreign key

Foreign Key is an essential concept in the field of database management and relational databases. It is a type of field or column in a database that acts as a reference to a corresponding field from another table in the same database, and is used to ensure referential integrity.

A primary key, also known as a unique identifier, is a code used to uniquely identify a record within a database table. The primary key field of one table is referred to as a foreign key in the other table – in essence, it represents a reference to the primary key of another table. Foreign Keys help ensure that the relationship between two tables in a database are enforced and that no data integrity issues occur.

For example, if there is a database table containing customer information and another containing orders from the customers, the foreign key would be a reference to the primary key of the customer table, such as a customer identification number or the customer’s name. This connection makes it able to track which customer made what order.

Foreign Keys are also important in order to enforce the various types of constraints when a database record is updated or deleted, such as ensuring that no orphaned records are created (records in one table with no corresponding record in another table). They are also used to ensure data integrity when fields are modified in one table.

Foreign Keys are an essential part of database management and used for a wide variety of tasks. They are necessary for normalizing data, ensuring that databases are properly updated, and enforcing various types of constraints. Without properly established Foreign Keys in the data, databases would become riddled with data integrity errors and fields would not remain properly updated or consistent.