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[MySQL] group and max problem...

Witam,
szukając w dokumentacji mysqla odpowiedzi na moje pytanie
trafiłem na taki przykład:

SELECT user, MAX(salary) as max_sel
FROM tmp
GROUP BY user HAVING max_sel = MAX(salary);

I faktycznie w tabeli, która na 2 kolumny wszystko działa dobrze
ale ja potrzebuję czegoś więcej :-)

CREATE TABLE `tmp` (
`id` int(11) NOT NULL auto_increment,
`user` char(50) default NULL,
`salary` int(10) default NULL,
`data` date default NULL,
PRIMARY KEY (`id`)
) TYPE=MyISAM

wprowadziłem do niej takie dane:
INSERT INTO `tmp` VALUES
(1,'mikolaj',50 ,'2006-01-01'),
(2,'mikolaj',15 ,'2004-02-02'),
(3,'mikolaj',20 ,'2004-03-03'),
(4,'mikolaj3',1 1,'2004-04-04'),
(5,'mikolaj3',4 0,'2005-05-05'),
(6,'mikolaj3',2 5,'2005-05-05');
Po dodaniu do selecta pola `data`

SELECT user, MAX(salary) as max_sel, `data`
FROM tmp
GROUP BY user HAVING max_sel = MAX(salary);

Otrzymuję taki wynik:
user salary data
mikolaj 50 2006-01-01
mikolaj3 40 2004-04-04

1 rekord jest ok (przez przypadek)
a drugi !!! pokazuje pierwszą datę z pogrupowanej grupy,
zamiast wartość `data` z rekordu gdzie jest MAX(salary).
Czy ktoś mógłby mnie oświecić dlaczego tak
się dzieje?
Niestaty nie można dodać po prostu
order by `data`, bo order jest wykonany po group :(

Jak wybrać dobre rekordy bez użycia tabel tymczasowych?
Czy kroś może mi pomóc?

Mysql 4.costam (bez podzapytan).

Mikolajj
Jul 20 '05 #1
0 3322

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