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Difference Between Primary key And Foreign key
In the world of databases, there are two important players: primary keys and foreign keys. They’re like puzzle pieces that help organize and connect information. Even though they both play a role in keeping things organized and accurate, they have different jobs. Let’s take a closer look at what makes primary keys and foreign keys different and how they each contribute to making databases work well.
What Is Primary Key?
A primary key is a designated aspect within a database table that emphasizes individuality. It is embodied by a singular column or a combination of columns, serving to distinguish each row within the database distinctly. Essentially, it precludes the presence of identical values across different rows, while also mandating the absence of NULL values.
What Is Foreign Key?
A foreign key is primarily utilized to create a connection between two tables. Its main role is to uphold the accuracy of data when dealing with two different sets of information that are related to each other.
Key Difference Between Primary Key and Foreign Key
| Sl. No | Primary Key | Foreign Key |
| 1 | A primary key aims on the uniqueness of the table and assures the value in the specific column is unique. | A foreign key is used to build a relationship between the two tables. |
| 2 | The primary key tables has only one primary key. | Whereas, Foreign key tables can allow more than one foreign key. |
| 3 | It doesn’t allow null values. | Foreign key accepts multiple null values. |
| 4 | It can identify the record uniquely in the database table. | A foreign key is a field in the table and primary key in another table. |
| 5 | In the primary key, the value cannot be removed from the parent table. | In contrast, the value can be deleted from the child table. |
| 6 | Its restriction can be completely defined on the temporary tables. | Its restriction cannot be defined on the global or local temporary tables. |
Conclusion
This article focus on the Key difference between primary and Foreign key. These two keys are important for the database . Hence, in short A primary key is used to assure the value in the particular column is unique. The foreign key provides the link between the two tables .
FAQ – Difference Between Primary key And Foreign key
Q1. What is a primary key and foreign key example?
Ans. In the student table, we store the details of students and the courses they have enrolled in. And in the department table, we store all the details of the department. Here the courseId acts as the Primary key for the department table whereas it acts as the Foreign key in the student table.
Q2. Can a foreign key be a primary key?
Ans. Foreign keys are almost always “Allow Duplicates,” which would make them unsuitable as Primary Keys. It is perfectly fine to use a foreign key as the primary key if the table is connected by a one-to-one relationship, not a one-to-many relationship.
Q3. What is the symbol for foreign key?
Ans. Foreign keys are denoted by the FK notation.
Hello, I’m Hridhya Manoj. I’m passionate about technology and its ever-evolving landscape. With a deep love for writing and a curious mind, I enjoy translating complex concepts into understandable, engaging content. Let’s explore the world of tech together