[Solved] Identify the error in this query:SELECT STRING_AGG(name, ', ' ORDER BY name) FROM users ORDER BY name; | PostgreSQL

PostgreSQL - Aggregate Functions and GROUP BY

Identify the error in this query:

SELECT STRING_AGG(name, ', ' ORDER BY name) FROM users ORDER BY name;

AORDER BY cannot be used inside STRING_AGG.

BThe query is correct and will run without errors.

CORDER BY must be inside STRING_AGG parentheses, not outside.

DORDER BY inside STRING_AGG must come after separator argument.

Step-by-Step Solution

Solution:

Step 1: Check ORDER BY usage inside STRING_AGG
ORDER BY inside STRING_AGG after the separator is valid syntax.
Step 2: Check outer ORDER BY
Without GROUP BY, the outer ORDER BY name causes an error because 'name' must appear in GROUP BY or be used in an aggregate function.
Final Answer:
ORDER BY must be inside STRING_AGG parentheses, not outside. -> Option C
Quick Check:
Outer ORDER BY invalid without GROUP BY = ORDER BY must be inside STRING_AGG parentheses, not outside. [OK]

Quick Trick: ORDER BY inside STRING_AGG works; outside requires GROUP BY in aggregate queries [OK]

Common Mistakes:

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