研究生做的
表A：ID 
  10001
  10002
  .
  .
  .
  10100
表B：NO ACTI
  980001 Y
  980002 Y
  980003 N
  .
  .
  .
  980100 Y
现在要根据这两个表把B表中字段ACTI为Y的增加到表C中去，表C的结果为
表C：NO ID RTY
  980001 10001 3
  980001 10002 3
  980001 10003 3
  ... ... 3
  980001 10100 3
  980002 10001 3
  980002 10002 3
  980002 10003 3
  ... ... 3
  980002 10100 3
  980004 10001 3
  980004 10002 3
  980004 10003 3
  ... ... 3
  980004 10100 3
  ... ...
 

------解决方案--------------------

SQL code

insert into c
select b.no,a.id,3
from a corss join b
where b.rty = 3

------解决方案--------------------

SQL code
insert into c
select a.id,b.no,3
from (select distinct id from a) a
join (select distinct no from b where ACTI='Y') b
on 1=1

------解决方案--------------------

SQL code

--> 测试数据: @表A
declare @表A table (col int)
insert into @表A
select 10001 union all
select 10002

declare @表B table (NO int,ACTI varchar(1))
insert into @表B
select 980001,'Y' union all
select 980002,'Y' union all
select 980003,'N'

select col,NO,3 as ACTI from @表A a cross join @表B b  where b.ACTI='Y'

/*
col         NO          ACTI
----------- ----------- -----------
10001       980001      3
10001       980002      3
10002       980001      3
10002       980002      3
*/