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Which statement best describes the performance difference between a JOIN and a subquery in SQL?

easy📝 Conceptual Q11 of 15
SQL - Subqueries
Which statement best describes the performance difference between a JOIN and a subquery in SQL?
AJOINs generally perform better because they combine tables in a single step.
BSubqueries always perform better because they run separately.
CJOINs and subqueries have the same performance in all cases.
DSubqueries are faster because they use less memory.
Step-by-Step Solution
Solution:
  1. Step 1: Understand how JOINs work

    JOINs combine rows from two or more tables in one operation, which is often optimized by the database engine.
  2. Step 2: Compare with subqueries

    Subqueries run separately and then feed results to the main query, which can be slower especially with large data.
  3. Final Answer:

    JOINs generally perform better because they combine tables in a single step. -> Option A
  4. Quick Check:

    JOIN performance > Subquery performance [OK]
Quick Trick: JOINs usually run faster than subqueries [OK]
Common Mistakes:
MISTAKES
  • Thinking subqueries always run faster
  • Assuming JOINs and subqueries are always equal
  • Believing subqueries use less memory

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