SQL cannot refer to an alias from the same output clause in which it was introduced. (It has nothing to do with quoting, which only allows otherwise invalid identifiers; some SQL vendors would have thrown an error, but SQLite appears "more relaxed" in the handling of this case.)
You could use a nested query (sqlfiddle).
SELECT fortytwo, fortytwo + 8 as fifty
FROM (
SELECT 42 AS fortytwo)
This works because the referenced identifier, fortytwo
, was introduced in a "previous" output clause.