请教一个今天遇到的关于随机出试题的SQL语句

[西川痱子]

今天去笔试：遇到一个题目，题目大概是这样的：
有一个试题表：T_EXAM {ID,type(1,2,3/表示试题类型)，difficulty(1,2/试题难度)，distinguish(1,2/区分)}
现在我要从题库随机抽出20道题，type：类型1的6道，2的7道，3的7道；difficulty：难度1的8道，2的12道；distinguish：区分1的13道，2的7道：请问能用SQL查询出来吗？
如果能用SQL查询出来，SQL语句该怎么写？

[blackkettle]

强悍。学习了！

[bingquan12]

[Quote=引用 98 楼 的回复:]

10L，85L解法都不错，85L的更好一点。。。。。
[/Quote]

我怎么没有看出来 85L是随即的？ 同样的数据，每次运行是不一样的结果吗？

[bingquan12]

[Quote=引用 117 楼 的回复:]
引用 98 楼 的回复:

10L，85L解法都不错，85L的更好一点。。。。。


我怎么没有看出来 85L是随即的？ 同样的数据，每次运行是不一样的结果吗？
[/Quote]

好吧，我试验了，果然不同。为什么?求解释！

[bingquan12]

[Quote=引用 118 楼 的回复:]

引用 117 楼 的回复:
引用 98 楼 的回复:

10L，85L解法都不错，85L的更好一点。。。。。


我怎么没有看出来 85L是随即的？ 同样的数据，每次运行是不一样的结果吗？


好吧，我试验了，果然不同。为什么?求解释！
[/Quote]

order by newguid() ... 学习了！

[samyou]

懂得运用算法都是牛人。

[huaan011]

不错！

[zxxhz]

加强学习中！

[txzsp]

LZ好像不应该用union all，而应该用union，由于是随机取的记录可能用union all会产生重复记录，这样的话是不是就违背了题目的本意了？

[dpchy]

学习中了，请问有没学习SQL的群呢！

[s19850904]

路过，学习，是数据库的哦

[专坑队友]

学习了 膜拜牛人中

[Jackile]

2楼的代码很精简~

[akemi_homura]

吾肿么愚昧的觉得10楼的只有19道题。。嘛。当然这不是重点了。 学习了。
[Quote=引用 10 楼 的回复:]
SQL code





create table #tb(
id int ,
[type] int,
[difficurity] int,
[distinguish] int);

insert into #tb select top 1 * from T_EXAM order by NEWID()

declare @……
[/Quote]

[敢不敢在来一次]

[Quote=引用 2 楼 的回复:]

简单的写应该是这样的，期待更牛逼的算法。
SQL code
select top 6 * from tb where type=1 and difficulty=1 and distinguish=1 oder by newid()
union all
select top 2 * from tb where type=2 and difficulty=1 and distinguish……
[/Quote]怎么这么流弊···

[天才在左疯子在右]

烦死了

[霜之哀伤额]

[Quote=引用 85 楼 的回复:]

SQL code


create table #t(
id int ,
[type] int,
[difficurity] int,
[distinguish] int);


declare @type1 int
declare @type2 int
declare @type3 int
declare @difficulty1 int
declare @……
[/Quote]

85楼的开头定义改成 DECLARE @t table(
id int ,
[type] int,
[difficurity] int,
[distinguish] int);
这样感觉比较好- -，而且while循环里面应该是#t，85楼确实给力

[霜之哀伤额]

整合了一下楼上大牛们的，直接执行即可，方便我们这种菜菜
DECLARE @T_EXAM table(
id int ,
[type] int,
difficurity int,
distinguish int);

insert into @T_EXAM(id,[type],difficurity,[distinguish])
select top 10000 row_number()over(order by newid()), abs(checksum(newid())%3)+1,abs(checksum(newid())%2)+1,abs(checksum(newid())%2)+1 from master.dbo.spt_values a

DECLARE @t table(
id int ,
[type] int,
[difficurity] int,
[distinguish] int);

declare @type1 int
declare @type2 int
declare @type3 int
declare @difficulty1 int
declare @difficulty2 int
declare @distinguish1 int
declare @distinguish2 int

set @type1=1
set @type2=2
set @type3=3
set @difficulty1=1
set @difficulty2=2
set @distinguish1=1
set @distinguish2=2

declare @i int
set @i = 1

while (@i <= 20)
begin

if (select COUNT(*) from @t where [TYPE]=1) = 6
set @type1 = 0
if (select COUNT(*) from @t where [TYPE]=2) = 7
set @type2 = 0
if (select COUNT(*) from @t where [TYPE]=3) = 7
set @type3 = 0
if (select COUNT(*) from @t where [difficurity]=1) = 8
set @difficulty1=0
if (select COUNT(*) from @t where [difficurity]=2) = 12
set @difficulty2=0
if (select COUNT(*) from @t where [distinguish]=1) = 13
set @distinguish1=0
if (select COUNT(*) from @t where [distinguish]=2) = 7
set @distinguish2=0

insert into @t
select top 1 *
from @T_EXAM te
where [TYPE] in (@type1,@type2,@type3)
and [difficurity] in (@difficulty1,@difficulty2)
and [distinguish] in (@distinguish1,@distinguish2)
and not exists(select * from @t t2 where te.[id]=t2.[id])
order by newid()

if @@RowCount = 0 --已没有符合记录
break;
else
set @i = @i + 1
end

select * from @t

[天才在左疯子在右]

不赞成top,虽然能够出来结果，但是没有随机性，建议用in或者exists就随机性

[wslejeff]

select * from ( select * from T_EXAM where id in( SELECT id FROM (select id from T_EXAM where type = 1 ORDER BY dbms_random.random) WHERE ROWNUM<=6 union all SELECT id FROM (select id from T_EXAM where type = 2 ORDER BY dbms_random.random) WHERE ROWNUM<=7 union all SELECT id FROM (select id from T_EXAM where type = 3 ORDER BY dbms_random.random) WHERE ROWNUM<=7 ) and id in ( SELECT id FROM (select id from T_EXAM where difficulty = 1 ORDER BY dbms_random.random) WHERE ROWNUM<=8 union all SELECT id FROM (select id from T_EXAM where difficulty = 2 ORDER BY dbms_random.random) WHERE ROWNUM<=12 ) and id in ( SELECT id FROM (select id from T_EXAM where distinguish = 1 ORDER BY dbms_random.random) WHERE ROWNUM<=13 union all SELECT id FROM (select id from T_EXAM where distinguish = 2 ORDER BY dbms_random.random) WHERE ROWNUM<=7 ) ORDER BY dbms_random.random ) WHERE ROWNUM<=20

[tel[phone]]

引用 2 楼 汤姆克鲁斯 的回复:

简单的写应该是这样的，期待更牛逼的算法。 SQL code ? 1234567 select top 6 * from tb where type=1 and difficulty=1 and distinguish=1 oder by newid() union allselect top 2 * from tb where type=2 and diffic……

我怎么执行这个sql是错误的啊？？？版本是2008