Question 16(b)Differentiate between primary key and foreign key.

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Accepted Answer

Primary KeyForeign KeyPrimary Key is a column or group of columns in a table that uniquely identify every row in that table.A foreign key is an attribute whose value is derived from the primary key of another table. A foreign key is used to represent the relationship between two tables.Primary key cannot have Null values.Foreign key can have Null values.There can be only one primary key in a table.Multiple foreign keys can exist in a table.It is used to enforce entity integrity and ensure data uniqueness.It is used to enforce referential integrity and maintain data consistency across related tables.

Primary Key	Foreign Key
Primary Key is a column or group of columns in a table that uniquely identify every row in that table.	A foreign key is an attribute whose value is derived from the primary key of another table. A foreign key is used to represent the relationship between two tables.
Primary key cannot have Null values.	Foreign key can have Null values.
There can be only one primary key in a table.	Multiple foreign keys can exist in a table.
It is used to enforce entity integrity and ensure data uniqueness.	It is used to enforce referential integrity and maintain data consistency across related tables.

Database Concepts — Question 18

Question 16(b)