SQL Server : how to use SQL statements to get the desired results -

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i can use cursors, it's inefficient. there better way use sql statements these results?

table： a

a1    id      a2 -------------------- aaa        8:30 bbb        9:30 ccc        10:00

table： b

id    ​b2 ----------    8:30    9:00    9:10    9:30    9:50    10:01    12:00

desired results：

id    b2    ​    ​a1 ---------------------    8:30    ​    ​aaa    9:00    ​    ​aaa    9:10    ​    ​aaa    9:30    ​    ​bbb    9:50    ​    ​bbb    10:00    ​    ​bbb    10:01       ccc        12:00       ccc

although not have method achieve,

because explanation not enough.you should explain why 9:30 ​bbb , why 10:00 bbb

i tried using sql server 2012+ 

declare @t table(a1 varchar(50),id varchar(50), a2 time) insert @t values  ('aaa','a','8:30') ,('bbb','a','9:30') ,('ccc','a','10:00')    --select *,lead(a2,1)over(order id ) a2_endtime @t  declare @t1 table(id varchar(50), ​b2 time) insert @t1 values  ('a','8:30') ,('a','9:00') ,('a','9:10') ,('a','9:30') ,('a','9:50') ,('a','10:01') ,('a','12:00')  ;with cte (  select *,lead(a2,1)over(order id ) a2_endtime @t ) --select * cte ,cte1 (select t1.id,t1.b2 @t1 t1 ) ,cte2 ( select * @t c not exists(select b2 cte1 c1 c1.b2=c.a2) ) ,cte3 ( select id,b2 cte1 union select id,a2 cte2  )  select t1.id,t1.b2  ,(select top 1 t.a1  cte t ((t.a2_endtime null , t1.b2>=t.a2 )  or (t.a2_endtime not null , (t1.b2 >= t.a2 , t1.b2< t.a2_endtime) ))) cte3 t1

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