Explain the use of primary and foreign key in DBMS with example. What is the role of foreign key?

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Suresh Chand · Accepted Answer

The primary key is used to identify data uniquely therefore two rows can’t have the same primary key. It can’t be null. On the other hand, foreign key is used to maintain a relationship between two tables. Primary of a table act as a foreign key in the other table. Foreign keys in a table Enforce Referential Integrity constraint. It can be more than once on the table. Example: Here we have two tables, Employee and Department, which contain the Information of Employees and Department, respectively. Employee: Department No Name 001 001 002 Peter 027 Jon Department: Department No Department Name 001 Sales 002 Marketing Here department no in the Employee table is a foreign key. As you can see, there are only two departments in the department table, but in the Employee table, if a new Employee is added with the department no 027, which is not a valid foreign key hence here concept of referential integrity comes into the picture it will prevent new Employee with the wrong department no to be added. Roles of Foreign Key: Foreign keys help you to migrate entities using a primary key from the parent table. A foreign key enables you to link two or more tables together. It makes your database data consistent. A foreign key can be used to match a column or combination of columns with primary key in a parent table. SQL foreign key constraint is used to make sure the referential integrity of the data parent to match values in the child table.

Explain the use of primary and foreign key in DBMS with example. What is the role of foreign key?

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Explain the use of primary and foreign key in DBMS with example. What is the role of foreign key?

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