SQL - LEFT and RIGHT JOIN
What happens to rows in the left table when there is no matching row in the right table in a
LEFT JOIN?What happens to rows in the left table when there is no matching row in the right table in a LEFT JOIN?
easy📝 Conceptual Q1 of 15
Step-by-Step Solution
Solution:
Step 1: Understand LEFT JOIN behavior
A LEFT JOIN returns all rows from the left table and matching rows from the right table.Step 2: Consider unmatched rows
If no match exists, the right table columns show NULL for those left table rows.Final Answer:
They appear with NULL values for the right table columns -> Option CQuick Check:
LEFT JOIN unmatched rows = NULL in right table columns [OK]
Quick Trick: LEFT JOIN keeps all left rows, fills right with NULL if no match [OK]
Common Mistakes:
MISTAKES- Thinking unmatched rows are removed
- Assuming unmatched rows cause errors
- Believing unmatched rows duplicate
Master "LEFT and RIGHT JOIN" in SQL
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