Re:

Dan Langille <dan(at)langille(dot)org> writes:
> WHERE lastlogin between current_date - interval \''' ||
> quote_literal(i - 1) || '' days\'
> AND current_date - interval \''' ||
> quote_literal(i) || '' days\''';

IIRC, quote_literal() puts single quotes around its result. So you have
too many quotes there. Given that you know i is an integer, you don't
really need quote_literal for it. Actually, you don't need EXECUTE
here at all. Why not just

FOR i IN 1..MaxDays LOOP
SELECT count(*)
INTO r
FROM users
WHERE lastlogin between current_date - (i-1) * interval ''1 day''
AND current_date - i * interval ''1 day'';
RETURN NEXT r;
END LOOP;

regards, tom lane