sql以0.5向下取整

[a578452523]

sql server 2000中，我想以0.5向下取整，
如 :
0 取整后为 0，
0.0<=@x<0.5 取整后为 0，
0.5<=@x<1 取整后为 0.5，
1<=@x<1.5 取整后为 1 ，
1.5<=@x<2 取整后为 1.5 ，
2<=@x<2.5 取整后为 2 ，
2.5<=@x<3 取整后为 2.5 ，
.......
以此类推。。
怎么实现？望越简洁越好!
之前也有发过“sql以0.5向上取整的帖子”，高手们用 ceiling(@a*2)/2 就解决了，但是现在要向下取整了，不知道咋办了，又来求助各位了！！！ 注意是向下哦！！

[姐只会简单SQL语句]

引用 4 楼 ap0405140 的回复:

create table a5(x decimal(5,1))

insert into a5(x)
 select 0 union all
 select 0.2 union all
 select 0.6 union all
 select 1.1 union all
 select 1.7 union all
 select 2.3 union all
 select 2.9


select x,
       x-x%0.5 'y'
from a5
 
/*
x                                       y
--------------------------------------- ---------------------------------------
0.0                                     0.0
0.2                                     0.0
0.6                                     0.5
1.1                                     1.0
1.7                                     1.5
2.3                                     2.0
2.9                                     2.5

(7 row(s) affected)
*/

nice

[哥眼神纯洁不]

select floor(@a*2)/2

[开着拖拉机泡妞]

select floor(0.5*2)/2--0.5

select floor(0.4*2)/2--0

[yiyishuitian]

select ceiling(1.22*2)/2 select floor(1.22*2)/2

[唐诗三百首]

create table a5(x decimal(5,1))

insert into a5(x)
 select 0 union all
 select 0.2 union all
 select 0.6 union all
 select 1.1 union all
 select 1.7 union all
 select 2.3 union all
 select 2.9


select x,
       x-x%0.5 'y'
from a5
 
/*
x                                       y
--------------------------------------- ---------------------------------------
0.0                                     0.0
0.2                                     0.0
0.6                                     0.5
1.1                                     1.0
1.7                                     1.5
2.3                                     2.0
2.9                                     2.5

(7 row(s) affected)
*/

[开着拖拉机泡妞]

引用 4 楼 ap0405140 的回复:

create table a5(x decimal(5,1))

insert into a5(x)
 select 0 union all
 select 0.2 union all
 select 0.6 union all
 select 1.1 union all
 select 1.7 union all
 select 2.3 union all
 select 2.9


select x,
       x-x%0.5 'y'
from a5
 
/*
x                                       y
--------------------------------------- ---------------------------------------
0.0                                     0.0
0.2                                     0.0
0.6                                     0.5
1.1                                     1.0
1.7                                     1.5
2.3                                     2.0
2.9                                     2.5

(7 row(s) affected)
*/

膜拜