Redundant column to maintain data integrity

Course Queries Syllabus Queries 2 years ago

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Posted on 16 Aug 2022, this text provides information on Syllabus Queries related to Course Queries. Please note that while accuracy is prioritized, the data presented might not be entirely correct or up-to-date. This information is offered for general knowledge and informational purposes only, and should not be considered as a substitute for professional advice.

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manpreet Tuteehub forum best answer Best Answer 2 years ago

 

Consider the following example:

Syllabus
-id 
-course_id 
FOREIGN KEY (course_id) REFERENCES Course(id)   

SyllabusItem 
-id
-syllabus_id 
FOREIGN KEY (syllabus_id) REFERENCES Syllabus(id)   

Course 
-id   

Class 
-id 
-course_id 
-syllabus_item_id 
-syllabus_id <--- redundant column 
FOREIGN KEY (course_id, syllabus_id) REFERENCES Syllabus (course_id, id)
FOREIGN KEY (syllabus_item_id, syllabus_id) REFERENCES SyllabusItem (id, syllabus_id)

The second foreign key constraint is used to ensure the Syllabus Item belongs to the Syllabus, which belongs to the Course the Class belongs to. But in order to maintain this relationship, we have to add a redundant column syllabus_id to Class.

Is there a more efficient way to achieve data integrity in this example?

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