Postgresql select until certain total amount is reached

Question

I was wondering if I could get any help with the following problem.

I have a table of transactions (simplified below) and I only want to select transactions until my

Answer 1

select T1.*
from Transactions as T1
where 6 - (select sum(T2.amount) 
               from Transactions as T2 where  T2.id <= T1.id
          ) >= 0
order by id asc

This query works on SQL Server if Postgres supports subqueries like SQL Server does it can help you