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How to use Foreign Key in SQL?

In this article, we will learn how A FOREIGN KEY in one table points to a PRIMARY KEY in another table?
Submitted by Bharti Parmar, on January 09, 2019

Basically, Foreign Key represents relationship between tables.


    column-name data_type (size) CONSTRAINT constraint-name  
    References  Table-name (Column-name)


Table 1:


Table 2:


First create a primary key in first table which is also called unique key.

Like this:

create table student 
(enroll number(6) primary key, s_name varchar(25), address varchar2(20), 
contact number(10) );

Second create foreign key by using second table.

Like this:

create table student_fees
(enroll number(6) constraint en_fk References Student (enroll) , course_fee number(8), 
status varchar2(6), amount number(10) );

Query to find student name, address, contact from the database.

Foreign result


In this article, we have learnt how to use foreign key and how it works and useful for us to retrieve data from the relational database? I hope you understand the concept; if you have any query, feel free to ask in the comment section.


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