What are the primary key and foreign key in MySQL?

In a MySQL database, the primary key is a field used to uniquely identify each row of data, ensuring that every row in the table has a distinct identifier. The primary key field must have a non-NULL value, and every row of data must have a unique primary key value.

Foreign keys are used to create relationships between tables, allowing for data association between them. A foreign key is a field in a table that contains the value of another table’s primary key, establishing a connection between the two tables. Foreign keys help ensure data integrity and consistency by referencing data from one table to another.

Primary keys and foreign keys play a crucial role in database design and querying processes, ensuring the integrity and consistency of data.