使用mysql选择结果生成二维坐标

我对mysql查询有疑问

我有一个表，下面有数据

From To Weight
--------------
A    B    1
A    C    3
B    C    2
D    E    4

我想得到如下的sql结果

(?) A   B   C   D   E
----------------------
A   0   1   3   0   0
B   0   0   2   0   0
C   0   0   0   0   0 
D   0   0   0   0   4
E   0   0   0   0   0

而原始表中的数据并没有确定。

---

我怎样才能做到这一点

如果您知道原始列，可以执行以下操作：

select c.col1,
       sum(case when to = 'A' then weight else 0 end) as a,
       sum(case when to = 'B' then weight else 0 end) as b,
       sum(case when to = 'C' then weight else 0 end) as c,
       sum(case when to = 'D' then weight else 0 end) as d,
       sum(case when to = 'E' then weight else 0 end) as d
from (select 'A' as col1 union all select 'B' union all select 'C' union all select 'D' union all select 'E'
     ) c left join
     t
     on t.from = c.col1
group by c.col1;

如果不知道原始列，可以将这些值组合成单个字符串：

select col1.col, 
       group_concat(col2.col, ':', t.weight order by col2.col)
from ((select `from` as col from t
      ) union   -- on purpose to remove duplicates
      (select `to` from t
      )
     ) col1 cross join
     ((select `from` as col from t
      ) union   -- on purpose to remove duplicates
      (select `to` from t
      )
     ) col2 left join
     t
     on col1.col = t.`from` and col2.col = t.`from`
group by col1.col;

---

如果你想要单独的列，不知道这些值，那么你需要动态SQL ./P>考虑在应用程序代码中处理这样的与显示相关的需求（例如：PHP、C++、java）。SQL不适合处理动态列数（使用动态名称）@MadhurBhaiya实际上我已经尝试过了，但原始数据的大小太大，无法在应用程序代码中处理。