Dec 27, 2024 · PRIMARY KEY FOREIGN KEY ; A primary key is used to ensure data in the specific column is unique. A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables. …

Apr 11, 2021 · A primary key is required to define a relational database table. A foreign key, is one or more columns for another table that references a table’s primary key. In some DBMS’s define foreign key constraints to protect this relationship.

A primary key uniquely identifies a row in a table, while a foreign key is used to link two tables together by referencing the primary key of the related table. The most important difference that you should note here is that a primary key cannot have a NULL value, whereas a foreign key can accept NULL values.

Let us now dive into the concept of Primary and Foreign keys by understanding the definition, syntax, and examples of both keys. What is a Primary Key in SQL? A Primary key is a unique column we set in a table to easily identify and locate data in queries.

Nov 7, 2009 · Primary Key: A primary key is a field or combination of fields that uniquely identify a record in a table, so that an individual record can be located without confusion. Foreign Key: A foreign key (sometimes called a referencing key) is a key used to link two tables together.

Jun 28, 2024 · A primary key constraint is a column that uniquely identifies every row in the table of the relational database management system, while a foreign key is a column that creates a relationship between two tables.

Apr 3, 2025 · In SQL Server, there are two keys - primary key and foreign key which seem identical, but actually, both are different in features and behaviors. A primary key acts as a unique ID for each record in a database, ensuring that every row is distinct.

Apr 17, 2025 · In summary, a primary key uniquely identifies records within its own table, while a foreign key establishes a link between two tables, referencing the primary key of another table. Discover the differences between primary and foreign keys in relational databases.

Apr 9, 2025 · The Difference Between Primary key and Foreign key in SQL is that a Primary key is an identifier that is specific to each record in a table. By referring to the Primary Key of another table, a Foreign Key creates a connection between two tables.

Jun 7, 2024 · EnrollmentID is the Primary Key. StudentID is a Foreign Key that references the StudentID in the Students table. The Foreign Key (StudentID in Enrollments) links each enrollment record to a specific student in the Students table. This tells us which student is taking which class. How Do Primary Keys and Foreign Keys Work Together?