PostgreSQL query to return results as a comma separated list

Question

Let say you have a SELECT id from table query (the real case is a complex query) that does return you several results.

The problem is how to get all id return in a single row, comma separated?

user_8591363 · Answer

use array_to_string() & array() function for the same.

select array_to_string(array(select column_name from table_name where id=5), ', ');

user_11582228 · Answer

Use this below query it will work and gives the exact result.

SELECT array_to_string(array_agg(id), ',') FROM table

Output : {1,2,3,4,5}

user_1001199 · Answer

SELECT array_agg(id, ',') FROM table

{1,2,3,4}

I am using Postgres 11 and EntityFramework is fetching it as array of integers.