利用CASE WHEN旋转表

在一行中显示出这个销售经理1～12月每月的销售数量:

SELECT   SALES_MGR,   
          MAX(CASE   MONTH   WHEN   1   THEN   SALES_AMT   ELSE   NULL   END)   AS   JAN,   
          MAX(CASE   MONTH   WHEN   2   THEN   SALES_AMT   ELSE   NULL   END)   AS   FEB,   
          MAX(CASE   MONTH   WHEN   3   THEN   SALES_AMT   ELSE   NULL   END)   AS   MAR,   
          MAX(CASE   MONTH   WHEN   4   THEN   SALES_AMT   ELSE   NULL   END)   AS   APR,   
          MAX(CASE   MONTH   WHEN   5   THEN   SALES_AMT   ELSE   NULL   END)   AS   MAY,   
          MAX(CASE   MONTH   WHEN   6   THEN   SALES_AMT   ELSE   NULL   END)   AS   JUN,   
          MAX(CASE   MONTH   WHEN   7   THEN   SALES_AMT   ELSE   NULL   END)   AS   JUL,   
          MAX(CASE   MONTH   WHEN   8   THEN   SALES_AMT   ELSE   NULL   END)   AS   AUG,   
          MAX(CASE   MONTH   WHEN   9   THEN   SALES_AMT   ELSE   NULL   END)   AS   SEP,   
          MAX(CASE   MONTH   WHEN   10   THEN   SALES_AMT   ELSE   NULL   END)   AS   OTC,   
          MAX(CASE   MONTH   WHEN   11   THEN   SALES_AMT   ELSE   NULL   END)   AS   NOV,   
          MAX(CASE   MONTH   WHEN   12   THEN   SALES_AMT   ELSE   NULL   END)   AS   DEC,   
FROM     SALES   
WHERE   SALES_MGR=?   
AND       TEAR=?;