How can tables in databases be related to each other?

Tables in databases can be related to each other in the following main ways:

1. One-to-one relationship (1:1)

   • Each record in the first table corresponds to exactly one record in the second.
   • For example, the Users table and the Profiles table, where each user has one profile.

2. One-to-many relationship (1:N)

   • One record in the first table is related to multiple records in the second.
   • For example, the Authors table and the Books table, where one author can have many books.

3. Many-to-many relationship (M:N)

   • Records in the first table can be related to multiple records in the second and vice versa.
   • Implemented through an intermediate join table.
   • For example, the Students table and the Courses table, where a student can attend multiple courses, and a course can have many students.

Relationships are implemented using foreign keys, which ensure data integrity and allow joins between tables.