Which relationship is implemented with a junction table containing foreign keys to both sides?

Which relationship is implemented with a junction table containing foreign keys to both sides?

• A. One-to-Many Relationship
• B. Foreign Key
• C. Many-to-Many Relationship
• D. Composite Index

Answer: (C)

Many-to-many relationships are modeled with a junction (bridge) table that holds foreign keys to both related tables. This special table connects many rows on one side to many rows on the other by pairing their primary keys. For example, in a system with students and courses, an Enrollment table would contain student_id and course_id as foreign keys. A student can be enrolled in many courses, and each course can have many students, and the Enrollment table records every unique pairing. You can also store extra details about the relationship in the junction table, like enrollment date or grade. Other options don’t fit because a one-to-many relationship is implemented with a foreign key in the many-side table pointing to the one-side table; a standalone foreign key is a constraint, not a relationship type; and a composite index is for query performance, not to model relationships.

Many-to-many relationships are modeled with a junction (bridge) table that holds foreign keys to both related tables. This special table connects many rows on one side to many rows on the other by pairing their primary keys. For example, in a system with students and courses, an Enrollment table would contain student_id and course_id as foreign keys. A student can be enrolled in many courses, and each course can have many students, and the Enrollment table records every unique pairing. You can also store extra details about the relationship in the junction table, like enrollment date or grade.

Other options don’t fit because a one-to-many relationship is implemented with a foreign key in the many-side table pointing to the one-side table; a standalone foreign key is a constraint, not a relationship type; and a composite index is for query performance, not to model relationships.