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Which situation best shows the need for a LEFT OUTER JOIN?

easy📝 Conceptual Q2 of 15
SQL - LEFT and RIGHT JOIN
Which situation best shows the need for a LEFT OUTER JOIN?
AWhen you want only matching records from both tables
BWhen you want to delete unmatched records from the left table
CWhen you want all records from the left table, even if no match in the right table
DWhen you want to combine tables without any NULL values
Step-by-Step Solution
Solution:

  1. Step 1: Define LEFT OUTER JOIN behavior

    LEFT OUTER JOIN returns all rows from the left table and matched rows from the right table; unmatched right rows become NULL.

  2. Step 2: Identify use case

    Use LEFT OUTER JOIN when you want to keep all left table rows regardless of matches in the right table.

  3. Final Answer:

    When you want all records from the left table, even if no match in the right table -> Option C

  4. Quick Check:

    LEFT OUTER JOIN use = keep all left rows [OK]
Quick Trick: Left outer join keeps all left table rows [OK]
Common Mistakes:
MISTAKES
  • Using INNER JOIN when unmatched left rows are needed
  • Confusing LEFT OUTER JOIN with RIGHT OUTER JOIN
  • Expecting no NULLs in outer join results

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