What types of relationships between tables in a database exist?

There are three main types of relationships between tables in databases:

1. One-to-One

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

2. One-to-Many

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

3. Many-to-Many

   • Records in the first table can be related to multiple records in the second table and vice versa.
   • Implemented through an intermediate table (e.g., Students, Courses, and the Students_Courses table).

These relationships help structure data and ensure data integrity in the database.