In this post, we will discuss the different types of Relationships of databases that have different types of relations like many to many, One to one, and too many relationships, and here we will explain along with certain examples of each to understand it better.
Different Relationships of Databases
There are three types of relationship between databases which are one-to-one, one-to-many, and many-to-many. so here one by one we will discuss all of them to get it done.
One To One Relationship
In a one-to-one relationship, one record in a table is associated with one and only one record in another table, and vice versa. For example, a person may have only one passport, and a passport may belong to only one person. This can be implemented by adding a foreign key column to one of the tables that references the primary key of the other table. The foreign key should be unique to ensure that there is a one-to-one relationship between the two tables.
Here we have taken an example to explain it with the help of a scenario.
Example: Table 1: Person (person_id, name, address, etc.) and Table 2: Passport (passport_id, passport_number, expiration_date, etc.)
Many To Many Relationship
In a many-to-many relationship, one record in a table can be associated with many records in another table and vice versa. For example, a student can enroll in many courses, and a course can have many students. This can be implemented by creating a third table, known as a junction table or linking table, that contains the foreign keys from both tables. The primary key of the junction table should be a composite key consisting of both foreign keys.
Example: Table 1: Student (student_id, name, email, etc.) and Table 2: Course (course_id, name, description, etc.) Table 3: Enrollment (enrollment_id, student_id, course_id)
One to many
In a one-to-many relationship, a record in one table can be associated with multiple records in another table, but each record in the second table can only be associated with one record in the first table.
Example:
Table 1: Customer (customer_id, name, email, etc.) and Table 2: Order (order_id, customer_id, order_date, total, etc.)
Overall, understanding the different types of relationships between tables is important for designing efficient and effective databases. Each relationship type has its own strengths and weaknesses, and choosing the appropriate type for a given scenario can help ensure that the database is well-designed and easy to maintain.
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