create table aaa(f1 int,f2 int,f3 int,f4 int,time time)
create table bbb(f1 int,f2 int,f3 int,f4 int,time time)
insert into aaa select 1,2,null,null,'12:00'
union all select 3,null,4,null,'13:00'
insert into bbb select null,null,13,14,'12:00'
union all select null,15,null,16,'13:00'
go
select f1=(case when aaa.f1 is null then bbb.f1 else aaa.f1 end),
       f2=(case when aaa.f2 is null then bbb.f2 else aaa.f2 end),
       f3=(case when aaa.f3 is null then bbb.f3 else aaa.f3 end),
       f4=(case when aaa.f4 is null then bbb.f4 else aaa.f4 end),
       aaa.time from aaa join bbb on aaa.time=bbb.time
结果为：
f1    f2    f3    f4    time
1    2    13    14    12:00:00.0000000
3    15    4    16    13:00:00.0000000

------解决方案--------------------

查oracle也有coalesce函数,功能刚好与SQL相同,
SQL code

create table taba
(f1 int, f2 int, f3 int, f4 int, times varchar(7))

insert into taba
select 1,2,null,null,'12:00' union all
select 3,null,4,null,'13:00'

create table tabb
(f1 int, f2 int, f3 int, f4 int, times varchar(7))

insert into tabb
select null,null,12,13,'12:00' union all
select null,15,null,16,'13:00'


select 
coalesce(a.f1,b.f1) f1,
coalesce(a.f2,b.f2) f2,
coalesce(a.f3,b.f3) f3,
coalesce(a.f4,b.f4) f4,
a.times
from taba a
inner join tabb b
on a.times=b.times

f1          f2          f3          f4          times
----------- ----------- ----------- ----------- -------
1           2           12          13          12:00
3           15          4           16          13:00

(2 row(s) affected)

------解决方案--------------------
探讨


查oracle也有coalesce函数,功能刚好与SQL相同,
SQL code

create table taba
(f1 int, f2 int, f3 int, f4 int, times varchar(7))

insert into taba
select 1,2,null,null,'12:00' union all
select 3,null,4,null,'13:00'
……


------解决方案--------------------
SQL code
--    ORACLE的方法，你试试看
create table aaa(f1 int,f2 int,f3 int,f4 int,time time)
create table bbb(f1 int,f2 int,f3 int,f4 int,time time)
insert into aaa select 1,2,null,null,'12:00'
union all select 3,null,4,null,'13:00'
insert into bbb select null,null,13,14,'12:00'
union all select null,15,null,16,'13:00'
go

--方法1
select    f1 = nvl(a.f1,b.f1),
        f2 = nvl(a.f2,b.f2),
        f3 = nvl(a.f3,b.f3),
        f4 = nvl(a.f4,b.f4),
        time = nvl(a.time , b.time)
from (select rownum as ID,* from aaa) a join
     (select rownum as ID,* from bbb) b on a.ID = b.ID
     
--方法2     
select    f1 = nvl(a.f1,b.f1),
        f2 = nvl(a.f2,b.f2),
        f3 = nvl(a.f3,b.f3),
        f4 = nvl(a.f4,b.f4),
        time = nvl(a.time , b.time)
from (select dense_rank() over (order by time) as ID,* from aaa) a join
     (select dense_rank() over (order by time) as ID,* from bbb) b on a.ID = b.ID


drop table aaa,bbb

------解决方案--------------------