实例说明

资料表结构(红色为主键)==>
主表:test_part_cost_tab(料号资料表)
part_no  varchar2(20)   
part_name  varchar2(50) 

从表:test_part_cost_dt_tab(料号成本资料表)
part_no varchar2(10) 
cost_id varchar2(5) 
cost number 

数据==>
主表资料:
 part_no  part_name
1 1000            name1000 
2 1001            name1001 
从表资料:
part_no cost_id  cost
1 1000        100              1.1 
2 1000        200              1.2 
3 1000        300              1.3
4 1000        321              1.321 
5 1001        100              2.1 

交叉资料==>
sql语句产生的结果
part_no  part_name cost_100 cost_200 cost_300 cost_321
1 1000          name1000       1.1                   1.2                 1.3        1.321
2 1001          name1001       2.1                   0                    0                0

具体的交叉sql语句写法:
select a.part_no,a.part_name,
--sum(b.cost)
sum(case when  b.cost_id = ''100'' then b.cost else 0 end) as cost_100,
sum(case when  b.cost_id = ''200'' then b.cost else 0 end) as cost_200,
sum(case when  b.cost_id = ''300'' then b.cost else 0 end) as cost_300,
sum(case when  b.cost_id = ''321'' then b.cost else 0 end) as cost_321

from test_part_cost_tab a,test_part_cost_dt_tab b
where a.part_no = b.part_no
group by a.part_no,a.part_name

ps: 若主表有资料,从表没有资料时,交叉后会没有相应的资料
解决办法是在where条件里用外连接
where a.part_no = b.part_no(+)

参考资料:
http://www.cnblogs.com/iouniuniu/archive/2004/04/05/5238.aspx  ==>此文的语法与本文的语法不同
http://it.icxo.com/htmlnews/2004/11/11/454293.htm  
http://www.itpub.net/176727.html