行列转换 – Adamhuan's Data Center – 【逻辑驱动数据】

SQL：行列转换（一）

下面的内容将呈现一个简单的行列转换的例子，行列转换的方式很多，不止一种。
eg.

SQL> select * from ginfo;

       GID GNAME
---------- ----------------------------------------
         1 Natural
         2 Human

SQL> select * from uinfo;

   USER_ID USERNAME             GID
---------- ------------- ----------
         1 Alice                  2
         2 Baby Angela            1
         3 Dolly                  2

SQL>
SQL> col "user list" for a40
SQL> run
  1* select u.gid,wm_concat(u.username) "user list" from uinfo u,ginfo g where u.gid=g.gid group by u.gid

       GID user list
---------- ----------------------------------------
         1 Baby Angela
         2 Alice,Dolly

SQL>

SQL> select * from ginfo;

GID GNAME

---------- ----------------------------------------

1 Natural

2 Human

SQL> select * from uinfo;

USER_ID USERNAME GID

---------- ------------- ----------

1 Alice 2

2 Baby Angela 1

3 Dolly 2

SQL>

SQL> col "user list" for a40

SQL> run

1* select u.gid,wm_concat(u.username) "user list" from uinfo u,ginfo g where u.gid=g.gid group by u.gid

GID user list

---------- ----------------------------------------

1 Baby Angela

2 Alice,Dolly

SQL>

——————————————————————————————————————————
Ending。[……]