A developer writes: CREATE TABLE Enrollment(student_id INT, course_id INT, PRIMARY KEY(student_id)); to represent many-to-many between Student and Course. What's wrong?

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SQL - Table Relationships

A developer writes: CREATE TABLE Enrollment(student_id INT, course_id INT, PRIMARY KEY(student_id)); to represent many-to-many between Student and Course. What's wrong?

ATable name is invalid

BForeign keys are missing

CData types are incorrect

DPrimary key should include both student_id and course_id

Step-by-Step Solution

Solution:

Step 1: Understand many-to-many junction table keys
Junction tables need composite primary keys including both foreign keys.
Step 2: Check primary key definition
Only student_id is primary key here; course_id should be included too.
Final Answer:
Primary key should include both student_id and course_id -> Option D
Quick Check:
Composite PK needed for many-to-many [OK]

Quick Trick: Many-to-many tables need composite primary keys [OK]

Common Mistakes:

MISTAKES

Using single column as primary key
Omitting foreign keys
Incorrect data types

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A developer writes: CREATE TABLE Enrollment(student_id INT, course_id INT, PRIMARY KEY(student_id)); to represent many-to-many between Student and Course. What's wrong?

Step 1: Understand many-to-many junction table keys

Step 2: Check primary key definition

Final Answer:

Quick Check:

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