Merging results in a row depending on another field

Question

Below is the source table and the output I am trying to achieve.

I would like each another_table.id to only appear once in the output, with subsequent values displaying in new columns

Answer 1

This will give you the output, given the table in your question. With CTEs instead of subqueries for added clarity...

with intials as(
SELECT id, 
another_table.id as another_table_id,
value as field_1
FROM
main_table
WHEN
variable.id = 1),

finals as(
SELECT id, 
another_table.id as another_table_id,
value as field_1
FROM
main_table
WHEN
variable.id = 2)

SELECT
initials.id,
initials.another_table_id
initials.value field_1,
finals.value field_2
FROM
initials
LEFT OUTER JOIN
finals on initials.another_table_id = finals.another_table_id;