不使用function計算給定兩個日期之間的工作日個數

　　
　　可能這就是Oracle的work_days函數的算法吧
　　
　　Calculating Working Days Without Using a Function
　　
　　This tip comes from Mike Selvaggio Senior DB Architect and DBA at Orsel Consulting Inc in North Brunswick NJ
　　
　　If you need to calculate working days between two dates and you cant create the Oraclerecommended working days function here is SQL that can accomplish the same task:
　　
　　SQL> set linesize
　　SQL> desc date_test
　　Name Null? Type
　　START_DT DATE
　　END_DT DATE
　　
　　SQL> select * from date_test
　　
　　SQL> /
　　
　　START_DT END_DT
　　
　　DEC DEC
　　DEC DEC
　　DEC DEC
　　DEC DEC
　　
　　SQL> select start_dt end_dt end_dt start_dt age
　　work_days(start_dt end_dt) from date_test;
　　
　　START_DT END_DT AGE WORK_DAYS(START_DTEND_DT)
　　
　　DEC DEC
　　DEC DEC
　　DEC DEC
　　DEC DEC
　　
　　
　　SQL> get workingdays
　　代碼
　　select　start_dt end_dt trunc(end_dt start_dt) age
　　(trunc(end_dt start_dt) (
　　(case
　　WHEN (to_number(to_char(start_dtD) )) > trunc(end_dt start_dt)+
　　THEN
　　ELSE
　　trunc( (trunc(end_dt start_dt) (to_number(to_char(start_dtD) ))) / ) + END) +
　　(case
　　WHEN mod(to_char(start_dtD)) > trunc(end_dt start_dt)
　　THEN
　　ELSE
　　trunc( (trunc(end_dtstart_dt) (mod(to_char(start_dtD))+)) / ) +
　　　END) ) ) workingdays
　　from date_test
　　
　　SQL> /
　　
　　START_DT END_DT AGE WORKINGDAYS
　　
　　DEC DEC
　　DEC DEC
　　DEC DEC
　　DEC DEC
From:http://tw.wingwit.com/Article/program/Java/JSP/201311/19526.html