sql查询转置

Question

表结构：
购物人           商品名称       数量
A                 甲             2
B                 乙             4
C                 丙             1
A                 乙             2
B                 丙             5  
通过查询得到： 购物人    甲       乙      丙
A          2        2      null
B          null     4       5
C          null     null    1

Answer 1

select  购物人,   decode( 商品名称 ,'甲' , 数量,null) ,
decode( 商品名称 ,'乙', 数量,null) ,
decode( 商品名称 ,'丙' , 数量,null) 
from tab

Answer 2

select  购物人,  
max((decode( 商品名称 ,'甲' , 数量,null)) , 
max((decode( 商品名称 ,'乙', 数量,null)) , 
max((decode( 商品名称 ,'丙' , 数量,null)) 
from tab
group by 购物人

Answer 3

http://topic.csdn.net/u/20100109/13/6a10c168-f190-4766-b838-adbf03c4ac7b.html?64992

Answer 4

select  购物人,  decode( 商品名称 ,'甲' , 数量,null) ,
decode( 商品名称 ,'乙', 数量,null) ,
decode( 商品名称 ,'丙' , 数量,null)
from tab