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

Although it may not be the most efficent way (as you're still, in essence, selecting everything first), I'd look at using a running total.

Something like:

SELECT
  *
FROM
  (
  SELECT
    id
    , date
    , amount
    , (SELECT SUM(amount) FROM Transactions WHERE id <= t.id) AS RunningTotal
  FROM
    Transactions t
) t1
WHERE
  t1.RunningTotal < 6