What makes a subquery 'correlated'?

Mediumsqlcorrelated-subqueries

It references a column from the outer query, so it's re-evaluated per outer rowCorrect answer
It can only be written in all capital letters
It cannot be used with the WHERE clause
It always runs faster than a non-correlated subquery

Show answer & explanation

Correct answer: A. It references a column from the outer query, so it's re-evaluated per outer row

Explanation

A correlated subquery references a column from the outer query, meaning it's effectively re-evaluated for each row the outer query considers.

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Mediumsqlcorrelated-subqueries

It references a column from the outer query, so it's re-evaluated per outer rowCorrect answer
It can only be written in all capital letters
It cannot be used with the WHERE clause
It always runs faster than a non-correlated subquery

Show answer & explanation

Correct answer: A. It references a column from the outer query, so it's re-evaluated per outer row

Explanation

A correlated subquery references a column from the outer query, meaning it's effectively re-evaluated for each row the outer query considers.

Practise 3 questions on this topic

Take SQL Subqueries — Timed Test (3 questions) — scored instantly, explanation for every question, no login.

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