SQL - LEFT and RIGHT JOIN
You have two tables: Students and Exams. You want to list all exams and include student names if available. Which JOIN should you use?
You have two tables: Students and Exams. You want to list all exams and include student names if available. Which JOIN should you use?
hard📝 Application Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Identify which table to keep all rows from
We want all exams listed, so Exams is the table to keep all rows from.Step 2: Choose JOIN type to keep all Exams rows
LEFT JOIN keeps all rows from the left table. To keep all Exams, Exams must be the left table.Step 3: Match correct syntax
LEFT JOIN Students ON Exams.student_id = Students.id means FROM Exams LEFT JOIN Students, which is correct.Final Answer:
LEFT JOIN Students ON Exams.student_id = Students.id -> Option CQuick Check:
Keep all Exams rows = LEFT JOIN with Exams as left table [OK]
Quick Trick: Keep all rows from Exams (left table) use LEFT JOIN [OK]
Common Mistakes:
MISTAKES- Using RIGHT JOIN with Exams as left table incorrectly
- Confusing which table is left or right
- Choosing LEFT JOIN when RIGHT JOIN is needed
Master "LEFT and RIGHT JOIN" in SQL
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