"Kevin Grittner" <kevin.gritt...@wicourts.gov> wrote: > Aren Cambre <a...@arencambre.com> wrote: > >> SELECT COUNT(*) >> FROM consistent.master >> WHERE citation_id IS NOT NULL >> UNION >> SELECT COUNT(*) >> FROM consistent.master >> UNION >> SELECT COUNT(*) >> FROM consistent.master >> WHERE citation_id IS NULL >> >> I got this result: >> >> 2085344 >> 2085343 >> 0 >> >> Not clear how adding a WHERE clause, whose only practical effect >> is to reduce the number of rows returned, could cause *more* rows >> to be returned. > Never assume that the rows will be returned in any particular > order from a query unless you specify ORDER BY. Hmm. That doesn't explain why the numbers don't add up, though. Is that a copy/paste from an actual query run, or was there some hand-editing there? In particular, you might easily get that result if that last line was really: WHERE citation_id = '' instead of the IS NULL test. In the ANSI standard and in PostgreSQL there is a big difference between an empty string and NULL, although there is at least one product I know of which breaks from standard compliance by treating them as equivalent. -Kevin
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