One-to-one relationship

One-to-one relationship is a type of relationship in database design where one record in a particular record type is related to only one record of another record type. In other words, it means that for each record in one table, there is only one corresponding record in another table.

Explanation:

- In a one-to-one relationship, two tables are linked together based on a common field or attribute. This common field is typically a primary key in one table and a foreign key in another table.
- One-to-one relationships are often used to split a large table into two smaller tables to improve data organization and reduce redundancy.
- In this type of relationship, the primary key of one table becomes the foreign key in another table. This ensures that each record in the first table is related to only one record in the second table.
- One-to-one relationships are useful when there is a need to separate out certain attributes or properties of a record into a separate table, while still maintaining a strong connection between the two tables.
- For example, consider a database for a company where each employee has a unique employee ID. The company may decide to store sensitive employee information, such as salary and performance reviews, in a separate table that is only accessible to authorized personnel. This creates a one-to-one relationship between the employee table and the sensitive information table.
- The one-to-one relationship ensures that each employee record is linked to only one corresponding record in the sensitive information table.
- One-to-one relationships can also be used to simplify complex data models by breaking them down into smaller, more manageable chunks.
- One-to-one relationships are less common compared to one-to-many relationships or many-to-many relationships, but they can be very useful in specific scenarios where data separation and organization are important.