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Why is it important to join tables on a primary key to foreign key relationship rather than arbitrary columns?

hard📝 Conceptual Q10 of 15
SQL - INNER JOIN
Why is it important to join tables on a primary key to foreign key relationship rather than arbitrary columns?
ABecause arbitrary columns always cause syntax errors
BBecause primary keys are always numeric
CBecause primary and foreign keys ensure referential integrity and correct matching
DBecause foreign keys contain duplicate values only
Step-by-Step Solution
Solution:

  1. Step 1: Understand referential integrity

    Primary and foreign keys enforce valid relationships between tables.

  2. Step 2: Importance of correct matching

    Joining on these keys ensures rows match correctly and data is consistent.

  3. Final Answer:

    Because primary and foreign keys ensure referential integrity and correct matching -> Option C

  4. Quick Check:

    Join on keys for integrity and correctness [OK]
Quick Trick: Join on keys to keep data consistent [OK]
Common Mistakes:
MISTAKES
  • Thinking arbitrary columns are safe to join
  • Assuming primary keys must be numeric
  • Misunderstanding foreign key duplicates

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