Which of the following is the correct syntax to aggregate the column city with ', ' separator using STRING_AGG?

easy📝 Syntax Q3 of 15

PostgreSQL - Aggregate Functions and GROUP BY

Which of the following is the correct syntax to aggregate the column city with ', ' separator using STRING_AGG?

ASELECT STRING_AGG(city, ',') FROM locations;

BSELECT STRING_AGG(city) FROM locations;

CSELECT STRING_AGG(city, ', ') FROM locations;

DSELECT STRING_AGG(city, city) FROM locations;

Step-by-Step Solution

Solution:

Step 1: Check syntax for STRING_AGG
STRING_AGG requires two arguments: the column and the separator string.
Step 2: Evaluate each option
SELECT STRING_AGG(city, ',') FROM locations; uses ',' (comma only, no space). SELECT STRING_AGG(city) FROM locations; misses separator argument. SELECT STRING_AGG(city, ', ') FROM locations; uses the correct ', ' separator. SELECT STRING_AGG(city, city) FROM locations; uses column as separator, which is invalid.
Final Answer:
SELECT STRING_AGG(city, ', ') FROM locations; -> Option C
Quick Check:
Correct syntax = column + separator string [OK]

Quick Trick: STRING_AGG needs column and separator string [OK]

Common Mistakes:

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