的样本数据
create table data (Country varchar(10), Number int);
insert into data select
'USA' , 300 union all select
'USA' , 450 union all select
'USA' , 500 union all select
'USA' , 100 union all select
'FR' , 100 union all select
'FR' , 420 union all select
'UK' , 300 union all select
'UK' , 400 union all select
'UK' , 1000;
第一种选择是使用像Scrum的梅斯特变量伪排名显示,但这里作为一个单独的语句
SELECT Country, Number
FROM (
SELECT
Number,
@r := case when @c=country then @r+1 else 1 end rownum,
@c := Country Country
FROM (select @r :=0 , @c := '') x, data
ORDER BY Country, Number DESC
) y
WHERE rownum < 3;
如果您正在使用这在前端,只需要2个计数,那么你可以使用这个表格返回一个列表中的计数(单列)
SELECT
Country,
left(x,locate(',',concat(x,','),locate(',',x)+1)-1) Numbers
FROM (
SELECT
a.Country,
Group_Concat(a.Number) x
From (
select country, number
from data
order by country, number desc) a
group by a.Country
) b
结果是
"Country";"Numbers"
"FR";"420,100"
"UK";"1000,400"
"USA";"500,450"
如果有可能发生联系,则第二形式的该变型中删除关系并示出了“每个国家顶部2个不同的数字”,作为记录。
SELECT distinct x.Country, x.Number
From data x
inner join
(
SELECT
Country,
left(x,locate(',',concat(x,','),locate(',',x)+1)-1) Numbers
FROM (
SELECT
a.Country,
Group_Concat(a.Number) x
From (
select distinct country, number
from data
order by country, number desc) a
group by a.Country
) b
) y on x.Country=y.Country
and concat(',',y.Numbers,',') like concat('%,',x.Number,',%')
order by x.Country, x.Number Desc
结果
"Country";"Number"
"FR";"420"
"FR";"100"
"UK";"1000"
"UK";"400"
"USA";"500"
"USA";"450"
还,如果你在第二个位置有重复的“数量”值......你只需要在这个速度的一个数字实例? – DRapp 2011-01-14 13:56:54