What is the difference between foreign key and primary key in sql

Berlin: Springer, Print [1]Ritchie, Colin. Relational Database Principles. Boston: Cengage, Print [2]Harrington, Jan L. Relational Database Design and Implementation. Burlington: Morgan Kaufmann, User assumes all risk of use, damage, or injury.

You agree that we have no liability for any damages. What is a Primary Key? What is a Foreign Key? Relation of Primary Key vs Foreign Key A primary key uniquely identifies a record in the relational database table, whereas a foreign key refers to the field in a table which is the primary key of another table.

Temporary Table of Primary Key vs Foreign Key A primary key constraint can be defined implicitly on temporary tables and their variables, whereas a foreign key constraint cannot be enforced on local or global temporary tables. Deletion of Primary Key vs Foreign Key A primary key value cannot be deleted from the parent table which is referred to as a foreign key in the child table. Primary Key vs.

Foreign Key: Comparison Chart Summary of Primary Key verses Foreign Key Keys play a crucial role in the existence of database schema to establish links between tables and within a table. Author Recent Posts. Sagar Khillar. He has that urge to research on versatile topics and develop high-quality content to make it the best read.

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You can say he is curious by nature. He believes everyone is a learning experience and it brings a certain excitement, kind of a curiosity to keep going. Latest posts by Sagar Khillar see all. Help us improve. Next Topic Primary Key vs Unique key. Reinforcement Learning. R Programming. React Native. Python Design Patterns. Python Pillow. Python Turtle. Verbal Ability. Interview Questions. Company Questions. Artificial Intelligence.

Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. Operating System. Computer Network. Compiler Design. Computer Organization. Discrete Mathematics. Ethical Hacking. Computer Graphics. Software Engineering. Web Technology. Cyber Security. C Programming. It is used to efficiently retrieve data from the database.

There are primarily three types of relationships 1 One-to-One, 2 One-to-many, 3 Many-to-many. A primary key constrain is a column or group of columns that uniquely identifies every row in the table of the relational database management system.

It cannot be a duplicate, meaning the same value should not appear more than once in the table. A table can have more than one primary key. Primary key can be defined at the column or the table level. If you create a composite primary key, it should be defined at the table level. Foreign key is a column that creates a relationship between two tables. The purpose of the Foreign key is to maintain data integrity and allow navigation between two different instances of an entity.

It acts as a cross-reference between two tables as it references the primary key of another table. Every relationship in the database should be supported by a foreign key. StudID is chosen as a primary key because it can uniquely identify other rows in the table. In the above example, we have two tables, a teacher and a department in a school.