[Solved] Consider these tables:students(id, name), courses(id, title), enrollments(student_id, course_id)What does this query return?SELECT s.name, c.title FROM students s LEFT JOIN enrollments e ON s.id = e.... | SQL

SQL - LEFT and RIGHT JOIN

Consider these tables:
students(id, name), courses(id, title), enrollments(student_id, course_id)
What does this query return?

SELECT s.name, c.title FROM students s LEFT JOIN enrollments e ON s.id = e.student_id LEFT JOIN courses c ON e.course_id = c.id;

AAll students with their enrolled courses; NULL if not enrolled.

BOnly students enrolled in courses.

CAll courses with enrolled students.

DOnly courses with students enrolled.

Step-by-Step Solution

Solution:

Step 1: Identify main table and joins
Main table is students. LEFT JOIN enrollments on student_id, then LEFT JOIN courses on course_id.
Step 2: LEFT JOIN preserves all students
All students appear. If no enrollment, course title is NULL.
Final Answer:
All students with their enrolled courses; NULL if not enrolled. -> Option A
Quick Check:
LEFT JOIN keeps all students = All students with their enrolled courses; NULL if not enrolled. [OK]

Quick Trick: LEFT JOIN keeps all left rows, NULLs for missing right rows [OK]

Common Mistakes:

MISTAKES

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