oracle decode 函數

DECODE 

文法: 

SELECT DECODE( <EXPR,SEARCH1,RESULT1,SEARCH2,RESULT2,...[,DEFAULT]>)FROM <TABLE_NAME>

e.g.:

select orderno,decode(ostatus,'p','準備處理','c','已完成') 

from order_master

此函數可用於行轉列:

select * from score

SELECT   u_id, stu_name,          SUM (DECODE (score_type, '語文', score, 0)) AS 語文, /*or use max()*/         SUM (DECODE (score_type, '數學', score, 0)) AS 數學,         SUM (DECODE (score_type, '外語', score, 0)) AS 外語    FROM score--where u_id>1GROUP BY u_id, stu_name--having u_id >1ORDER BY u_id