相近值
各位大！我在查遇到个难题！如表中有 1,100,200,300 等数值，当使用10到表中查询时需要返回 1,260 时返回 200 都是要找等于或小于的行。请问大家有没有好的方法。 sql
[解决办法]

;with t(id ,a   ,b)
as
(
select 1, 1,   'a56'
union all select 2,  100, 'b68'
union all select 3,  200, 'e98'
union all select 4,  300, 'f15'
),

condition(id, 条件)
as
(
select 1,  60
union all select 2 , 75
union all select 3 , 250
union all select 4 , 310
)

select tt.id,tt.b
from
(
select t.*,
       row_number() over(partition by c.id,c.条件 order by t.a desc) as rownum
from t
inner join condition c
        on t.a <= c.条件
)tt
where rownum = 1
/*
idb
1a56
1a56
3e98
4f15
*/

create table 源数据
(id int,a int,b varchar(10))

insert into 源数据
 select 1,1,'a56' union all
 select 2,100,'b68' union all
 select 3,200,'e98' union all
 select 4,300,'f15'

create table 条件数据
(id int,条件 int)

insert into 条件数据
 select 1,60 union all
 select 2,75 union all
 select 3,250 union all
 select 4,310


select a.id,
       (select top 1 b.[b] 
        from 源数据 b  
        where b.[a]<a.条件
        order by b.id desc) 'bb'
 from 条件数据 a

/*
id          bb
----------- ----------
1           a56
2           a56
3           e98
4           f15

(4 row(s) affected)
*/