Re: Counting booleans in GROUP BY sections

Thank you Adrian, but -

On Fri, Nov 29, 2019 at 6:45 PM Adrian Klaver <[email protected]>
wrote:

> On 11/29/19 8:38 AM, Alexander Farber wrote:
> >
> > CREATE OR REPLACE FUNCTION words_list_puzzles(
> >                  in_start interval,
> >                  in_end interval
> >
> >          ) RETURNS TABLE (
> >                  out_label  text,
> >                  out_count  bigint,
> >                  out_puzzle boolean,
> >                  out_mid    bigint,
> >                  out_secret text,
> >                  out_gid    integer,
> >                  out_score  integer
> >          ) AS
> > $func$
> >
> >      SELECT
> >          TO_CHAR(played, 'Mon YYYY') AS label,
> >          COUNT(NULLIF(puzzle, FALSE)), -- this only returns 0 or 1, why?
>
> If I am following it is because you have mid in GROUP BY and mid is a
> PK. Since mid will always be unique you will have at most on row per group.
>
> >          puzzle,
> >          mid,
> >          MD5(mid || ‘my little secret’) AS secret,
> >          gid,
> >          score
> >
> >      FROM words_moves
> >      WHERE action = 'play'
> >      AND LENGTH(hand) = 7
> >      AND (LENGTH(letters) = 7 OR score > 90)
> >      AND played > CURRENT_TIMESTAMP - in_start
> >      AND played < CURRENT_TIMESTAMP - in_end
> >      GROUP BY label, puzzle, mid, secret, gid, score
> >      ORDER BY played DESC
> >
> > $func$ LANGUAGE sql STABLE;
> >
> > But when I run it, I only get 0 or 1 in the out_count column:
> >
> > words_ru=> select * from words_list_puzzles(interval '2 year', interval
> > '1 year');
> >   out_label | out_count | out_puzzle | out_mid |            out_secret
> >           | out_gid | out_score
> >
> -----------+-----------+------------+---------+----------------------------------+---------+-----------
> >   Nov 2018  |         0 | f          | 1326876 |
> > e4928d3c34f50b8e6eabf7bad5b932fe |   46007 |        28
> >   Nov 2018  |         0 | f          | 1324466 |
> > 6228ba509a7124f485feb5c1acbb6b68 |   45922 |        26
> >   Nov 2018  |         0 | f          | 1322050 |
> > b67b091d383678de392bf7370c735cab |   45877 |        34
> >   Nov 2018  |         0 | f          | 1320017 |
> > 35f03b0c7159cec070c00aa80359fd42 |   44255 |       120
> >   Nov 2018  |         0 | f          | 1319160 |
> > 83df42f7ad398bbb060fc02ddfdc62c0 |   45031 |        95
> > .....
> >   May 2018  |         0 | f          |  264251 |
> > 2fff1154962966b16a2996387e30ae7f |   10946 |        99
> >   May 2018  |         1 | t          |  257620 |
> > 645613db6ea40695dc967d8090ab3246 |   12713 |        93
> >   May 2018  |         0 | f          |  245792 |
> > bb75bfd9cb443ff541b199d893c68117 |   12359 |        24
> >   May 2018  |         1 | t          |  243265 |
> > d899a5d642ccd96d931194f48ef56d53 |   11950 |       123
> >   May 2018  |         0 | f          |  231953 |
> > ad53b5b2c0d4cced3d50e8b44ad53e55 |   11910 |        32
> >
> > - while I was hoping to get 2 for the "May 2018" section.
> >
> > What am I doing wrong please, why don't the values add up? Below is the
> > table desc:
> >
> > words_ru=> \d words_moves
> >                                        Table "public.words_moves"
> >   Column  |           Type           | Collation | Nullable |
> >        Default
> >
> ---------+--------------------------+-----------+----------+------------------------------------------
> >   mid     | bigint                   |           | not null |
> > nextval('words_moves_mid_seq'::regclass)
> >   action  | text                     |           | not null |
> >   gid     | integer                  |           | not null |
> >   uid     | integer                  |           | not null |
> >   played  | timestamp with time zone |           | not null |
> >   tiles   | jsonb                    |           |          |
> >   score   | integer                  |           |          |
> >   letters | text                     |           |          |
> >   hand    | text                     |           |          |
> >   puzzle  | boolean                  |           | not null | false
> > Indexes:
> >      "words_moves_pkey" PRIMARY KEY, btree (mid)
> >      "words_moves_gid_played_idx" btree (gid, played DESC)
> >      "words_moves_uid_action_played_idx" btree (uid, action, played)
> >      "words_moves_uid_idx" btree (uid)
> > Check constraints:
> >      "words_moves_score_check" CHECK (score >= 0)
> > Foreign-key constraints:
> >      "words_moves_gid_fkey" FOREIGN KEY (gid) REFERENCES
> > words_games(gid) ON DELETE CASCADE
> >      "words_moves_uid_fkey" FOREIGN KEY (uid) REFERENCES
> > words_users(uid) ON DELETE CASCADE
> > Referenced by:
> >      TABLE "words_scores" CONSTRAINT "words_scores_mid_fkey" FOREIGN KEY
> > (mid) REFERENCES words_moves(mid) ON DELETE CASCADE
> >
>
>
if I remove GROUP BY mid, then I get the error:

ERROR:  42803: column "words_moves.mid" must appear in the GROUP BY clause
or be used in an aggregate function
LINE 18:         mid,
                 ^
LOCATION:  check_ungrouped_columns_walker, parse_agg.c:1369

Regards
Alex