现有“select * from t where a in (5,3,2,1,8,9,30...)" 假设 a 是主键，in里面的参数是唯一的。现要求输出的结果集按照 in 提供的参数顺序排序。而不是按照a本身的排序规则排序? 。
另：如果不要求使用临时表或表变量，那么又有什么办法实现。？
临时表方案参卡：
create table #t(id int identity(1,1),a int)
insert into #t values(5)
insert into #t values(3)
insert into #t values(2)
insert into #t values(1)
insert into #t values(8)
insert into #t values(9)
insert into #t values(30)
select t.* from t,#t as t1 where t.a=t1.a order by t1.id
如果不用临时表：(该方法极度不推荐，N倍的扫描全表时间）
select * from t where a=5 union all
select * from t where a=3 union all
select * from t where a=2 union all
select * from t where a=1 union all
select * from t where a=8 union all
select * from t where a=9 union all
select * from t where a=30