SQL - LEFT and RIGHT JOIN
What is the primary effect of using a
LEFT JOIN instead of an INNER JOIN in SQL?What is the primary effect of using a LEFT JOIN instead of an INNER JOIN in SQL?
easy📝 Conceptual Q1 of 15
Step-by-Step Solution
Solution:
Step 1: Understand JOIN types
INNER JOIN returns only matching rows from both tables.Step 2: LEFT JOIN behavior
LEFT JOIN returns all rows from the left table, and NULLs for unmatched right table rows.Final Answer:
It returns all rows from the left table, including those without matching rows in the right table. -> Option AQuick Check:
LEFT JOIN preserves all left rows [OK]
Quick Trick: LEFT JOIN keeps all left table rows, unmatched get NULLs [OK]
Common Mistakes:
MISTAKES- Confusing LEFT JOIN with INNER JOIN
- Assuming RIGHT JOIN returns left table rows
- Thinking LEFT JOIN filters unmatched rows
Master "LEFT and RIGHT JOIN" in SQL
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