How to return only values from SELECT and WHERE IN query?

Question

I have the following table - orders:

id	value	price	amount
2	'orange'	$12	7
8	'yellow'	$14	29
5	'green'	$17	9

I have to perform SELECT query with WHERE IN clause

SELECT value FROM order WHERE id IN (2, 5);

or using Knex.js

knex('orders)
      .select('value')
      .whereIn('id', [2, 5])

it returns me an array of objects:

[{value: 'orange'}, {value: 'green'}] 

how is it possible to return only array of values using PostgreSQL syntax?

['orange', 'green']

Answer 1

Using SQL:

SELECT DISTINCT array_agg(value) AS values
FROM orders
WHERE id IN (2, 5);

Using Knex.js

const values = await knex.raw(`
    SELECT DISTINCT array_agg(value) AS values
    FROM orders
    WHERE id IN (2, 5)
`);

Answer 2

Using pluck:

knex('orders')
      .select('value')
      .whereIn('id', [2, 5])
      .pluck('value')