林臨的地盤

SQL> select * from t1;

        N1 V1                NID
---------- ---------- ----------
         1 aa                 61
         2 aa                 62
         3 bb                 83
         4 aa                 64

SQL> select exp(sum(ln(nid))) from t1 where v1='aa';

EXP(SUM(LN(NID)))
-----------------
           242048

已用時間:  00: 00: 00.02

驗證一下:)
SQL> select 61*62*64 from dual;

  61*62*64
----------
    242048

已用時間:  00: 00: 00.00

先分組然后求積
SQL> select exp(sum(ln(nid))) from t1 group by v1;

EXP(SUM(LN(NID)))
-----------------
           242048
               83


oracle 這東東挺有意思.
轉自:http://blog.sina.com.cn/s/blog_54eeb5d901000ae5.html