问个sql语句怎么写 高分！
table1有字段ID,A,D   table2有字段ID,B,E

现在想做个视图

显示   ID，字段A，B   并在视图中新加字段C，并对C赋值  

if   B为空   then   C=A   else   C=B

两张表通过table1.ID=table2.ID关联

请问sql怎么写


------解决方案--------------------
select table1.ID, A, B, isnull(B,A) as C
from table1, table2
where table1.ID=table2.ID
------解决方案--------------------
select a.ID,a.A,b.B,C= case when B= " " then A else B from table1 a,table2 b where a.ID = b.ID
------解决方案--------------------
---创建视图
create view V_Dis
as
select a.ID, a.A, b.B, C=isnull(b.B,a.A)
from table1 a inner join table2 b
on a.id=b.id
go
---查看视图
select * from V_Dis

------解决方案--------------------
--
create view v_1
as
select t.id,t.a,t1.b,c=isnull(t1.b,t.a)
from table1 t inner join table2 t1 on t.ID=t1.ID

GO

select * from v_1