In which scenario is a correlated subquery typically less efficient than a JOIN?
Answer options
A
When the subquery returns a single value
B
When the outer query has very few rows
C
When the subquery executes once for each row of the outer query on a large table
D
When used with EXISTS on an indexed column
Correct answer: When the subquery executes once for each row of the outer query on a large table
Detailed Solution & Conceptual Analysis
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Key Engineering Takeaway
In Database Management, understanding the underlying mechanics of SQL is critical for writing performant, bug-free production code and passing rigorous technical architecture reviews.