有沒有一種簡單的方法可以將group by結果限制在前2位。以下查詢返回所有結果。使用「 limit 2」將整個列表減少到僅前2個條目。
select distinct(rating_name),
id_markets,
sum(rating_good) 'good',
sum(rating_neutral)'neutral',
sum(rating_bad) 'bad'
from ratings
where rating_year=year(curdate()) and rating_week= week(curdate(),1)
group by rating_name,id_markets
order by rating_name, sum(rating_good)
desc
結果如下：
波蘭78 48 24 12
波蘭1 15 5 0
波蘭23 12 6 3
波蘭2 5 0 0
波蘭3 0 5 0
波蘭4 0 0 5
愛爾蘭1 9 3 0
愛爾蘭2 3 0 0
愛爾蘭3 0 3 0
愛爾蘭4 0 0 3
法國12 24 12 6
法國1 3 1 0
法國231 1 0 0
法國2 1 0 0
法國4 0 0 1
法國3 0 1 0
謝謝喬恩
根據要求，我附上了**結構和一些測試資料的副本。我的目標是建立乙個檢視，該檢視具有每個唯一的rating_name的前2個結果
create table `zzratings` (
`id` int(11) not null auto_increment,
`id_markets` int(11) default null,
`id_account` int(11) default null,
`id_users` int(11) default null,
`datetime` timestamp null default current_timestamp,
`rating_good` int(11) default null,
`rating_neutral` int(11) default null,
`rating_bad` int(11) default null,
`rating_name` varchar(32) default null,
`rating_year` smallint(4) default null,
`rating_week` tinyint(4) default null,
`cash_balance` decimal(9,6) default null,
`cash_spend` decimal(9,6) default null,
primary key (`id`),
key `rating_year` (`rating_year`),
key `rating_week` (`rating_week`),
key `rating_name` (`rating_name`)
) engine=myisam auto_increment=2166690 default charset=latin1;
insert into `zzratings` (`id`,`id_markets`,`id_account`,`id_users`,`datetime`,`rating_good`,`rating_neutral`,`rating_bad`,`rating_name`,`rating_year`,`rating_week`,`cash_balance`,`cash_spend`)
values
(63741, 1, null, 100, null, 1, null, null, 'poland', 2010, 15, null, null),
(63742, 1, null, 101, null, 1, null, null, 'poland', 2010, 15, null, null),
(1, 2, null, 102, null, 1, null, null, 'poland', 2010, 15, null, null),
(63743, 3, null, 103, null, null, 1, null, 'poland', 2010, 15, null, null),
(63744, 4, null, 104, null, null, null, 1, 'poland', 2010, 15, null, null),
(63745, 1, null, 105, null, 1, null, null, 'poland', 2010, 15, null, null),
(63746, 1, null, 106, null, null, 1, null, 'poland', 2010, 15, null, null),
(63747, 5, null, 100, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63748, 5, null, 101, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63749, 2, null, 102, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63750, 3, null, 103, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63751, 4, null, 104, null, null, null, 1, 'ireland', 2010, 15, null, null),
(63752, 1, null, 105, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63753, 1, null, 106, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63754, 1, null, 100, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63755, 1, null, 101, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63756, 2, null, 102, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63757, 34, null, 103, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63758, 34, null, 104, null, null, null, 1, 'ireland', 2010, 15, null, null),
(63759, 34, null, 105, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63760, 34, null, 106, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63761, 21, null, 100, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63762, 21, null, 101, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63763, 21, null, 102, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63764, 21, null, 103, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63765, 4, null, 104, null, null, null, 1, 'ireland', 2010, 15, null, null),
(63766, 1, null, 105, null, 1, null, null, 'ireland', 2010, 15, null, null),
(63767, 1, null, 106, null, null, 1, null, 'ireland', 2010, 15, null, null),
(63768, 1, null, 100, null, 1, null, null, 'france', 2010, 15, null, null),
(63769, 1, null, 101, null, 1, null, null, 'france', 2010, 15, null, null),
(63770, 2, null, 102, null, 1, null, null, 'france', 2010, 15, null, null),
(63771, 3, null, 103, null, null, 1, null, 'france', 2010, 15, null, null),
(63772, 4, null, 104, null, null, null, 1, 'france', 2010, 15, null, null);
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