DATABASED MANAGEMENT SYSTEM - [ Relationship]

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A database relationship refers to the association between tables in a relational database. It establishes a connection between the data stored in different tables, enabling the database to represent complex data structures and support efficient data retrieval and manipulation.


There are Three types of database relationships, including:

One-to-One (1:1) Relationship: 

In this type of relationship, one record in a table is associated with only one record in another table, and vice versa. For example, a table of employees may have a corresponding table for their personal information, where each employee has a unique entry.

One-to-Many (1:N) Relationship:

This relationship occurs when a single record in one table can be associated with multiple records in another table. It is the most common type of relationship. For instance, in a database for a library, a single author may have written multiple books, creating a one-to-many relationship between the authors table and the books table.

Many-to-Many (N:M) Relationship: 

This relationship arises when multiple records in one table can be associated with multiple records in another table. In this case, an intermediate table, known as a junction table or associative table, is used to link the two tables. For example, in a database for a school, a student can enroll in multiple courses, and each course can have multiple students, resulting in a many-to-many relationship. The junction table would store the student ID and course ID to represent this relationship.

To establish these relationships, databases use primary and foreign keys. A primary key uniquely identifies a record in a table, while a foreign key is a field in a table that refers to the primary key in another table.

The relationships between tables help maintain data integrity, improve data consistency, and enable the database to efficiently retrieve and manage related information. They are crucial for designing and implementing effective relational databases of the Systems.

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