的樣本數據
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;
第一種選擇是使用像Scrum的梅斯特變量僞排名顯示,但這裏作爲一個單獨的語句
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;
如果您正在使用這在前端,只需要2個計數,那麼你可以使用這個表格返回一個列表中的計數(單列)
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
結果是
"Country";"Numbers"
"FR";"420,100"
"UK";"1000,400"
"USA";"500,450"
如果有可能發生聯繫,則第二形式的該變型中刪除關係並示出了「每個國家頂部2個不同的數字」,作爲記錄。
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
結果
"Country";"Number"
"FR";"420"
"FR";"100"
"UK";"1000"
"UK";"400"
"USA";"500"
"USA";"450"
還,如果你在第二個位置有重複的「數量」值......你只需要在這個速度的一個數字實例? – DRapp 2011-01-14 13:56:54