SQL Server: collect values in an aggregation temporarily and re-use in the same query

Question

How do I accumulate values in T-SQL? AFAIK there is no ARRAY type.
I want to re-use the values in the same query like demonstrated in this PostgreSQL example using array

Answer 1

If you're just collecting some values to reuse, try a table variable rather than a temp table

DECLARE @t TABLE 
(
    id INT PRIMARY KEY,
    name NVARCHAR(100)
)

INSERT @t VALUES (3 , 'John')
-- etc

The table variable is in-memory only, instead of going in the tempdb database like a temp table does.

Check Should I use a #temp table or table variable for more information.