You have two tables from an ER diagram: Student(id, name) and Enrollment(student_id, course_id). You want to add a foreign key constraint to Enrollment.student_id. Which SQL statement is correct?

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SQL - Table Relationships

You have two tables from an ER diagram: Student(id, name) and Enrollment(student_id, course_id). You want to add a foreign key constraint to Enrollment.student_id. Which SQL statement is correct?

AALTER TABLE Enrollment ADD FOREIGN KEY (student_id) REFERENCES Student(id);

BALTER TABLE Student ADD FOREIGN KEY (id) REFERENCES Enrollment(student_id);

CCREATE FOREIGN KEY Enrollment.student_id REFERENCES Student.id;

DALTER Enrollment ADD CONSTRAINT FOREIGN KEY student_id Student(id);

Step-by-Step Solution

Solution:

Step 1: Identify the correct syntax for adding foreign key
The standard syntax is ALTER TABLE [table] ADD FOREIGN KEY (column) REFERENCES [other_table](column).
Step 2: Apply to given tables
Enrollment.student_id references Student.id, so the statement must alter Enrollment table.
Final Answer:
ALTER TABLE Enrollment ADD FOREIGN KEY (student_id) REFERENCES Student(id); -> Option A
Quick Check:
ALTER TABLE + ADD FOREIGN KEY + REFERENCES [OK]

Quick Trick: Foreign key added on referencing table with ALTER TABLE [OK]

Common Mistakes:

MISTAKES

Adding foreign key on referenced table
Wrong ALTER TABLE syntax
Using CREATE FOREIGN KEY instead of ALTER TABLE

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You have two tables from an ER diagram: Student(id, name) and Enrollment(student_id, course_id). You want to add a foreign key constraint to Enrollment.student_id. Which SQL statement is correct?

Step 1: Identify the correct syntax for adding foreign key

Step 2: Apply to given tables

Final Answer:

Quick Check:

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