sql - Store select query's output in one array in postgres

Question

My code is:

SELECT column_name
FROM information.SCHEMA.columns
WHERE table_name = 'aean'

It returns column names of table aean.
Now I have declared an array:

DECLARE colnames text[]

How can I store select's output in colnames array.
Is there any need to initialize colnames?

Answer 1

There are two ways. One is to aggregate:

SELECT array_agg(column_name::TEXT)
FROM information.schema.columns
WHERE table_name = 'aean'

The other is to use an array constructor:

SELECT ARRAY(
    SELECT column_name 
    FROM information_schema.columns 
    WHERE table_name = 'aean'
)

I'm presuming this is for plpgsql. In that case you can assign it like this:

colnames := ARRAY(
    SELECT column_name
    FROM information_schema.columns
    WHERE table_name='aean'
);