Difference in foreign key and primary key

Question

Accepted Answer

Foreign key is a field in a table that refers to the primary key of another table.

Primary key uniquely identifies a record in a table, while foreign key establishes a link between two tables.
Primary key cannot have duplicate values, while foreign key can have duplicate values.
Primary key is used to enforce entity integrity, while foreign key is used to enforce referential integrity.
Foreign key helps in establishing relationships between tables and maintaining data integrity.
Example: In a database of students and courses, student_id can be a foreign key in the courses table, referring to the primary key student_id in the students table.

Accepted Answer

Primary key is always unique, foreign key can be unique and can be duplicated also. Foreign key is the unique primary key of another table and is the link to that table to join.

Difference in foreign key and primary key

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