datediff()是SQLServer的函數(shù)拷窜，如果要在oracle中填寫此函數(shù)，如下操作氢架。
1.建CDate函數(shù)
CREATE OR REPLACE Function CDate(Datechar In Varchar2) Return Date Is
ReallyDo Date;
Begin
Select to_date(to_char(to_date(to_char(Datechar), 'YYYY-MM-DD HH24:MI:SS'),
'YYYY-MM-DD'),
'YYYY-MM-DD')
Into ReallyDo
From Dual;
Return(ReallyDo);
End CDate;
2.建CDateTime函數(shù)
CREATE OR REPLACE Function CDateTime(Datechar In Varchar2) Return Date Is
ReallyDo Date;
Begin
Select to_date(to_char(to_date(to_char(Datechar), 'YYYY-MM-DD HH24:MI:SS'),
'YYYY-MM-DD HH24:MI:SS'),
'YYYY-MM-DD HH24:MI:SS')
Into ReallyDo
From Dual;
Return(ReallyDo);
End CDateTime;
3.建Datediff函數(shù)
CREATE OR REPLACE Function Datediff(Datepart In Varchar2,
StartDate In Varchar2,
EndDate In Varchar2) Return Number Is
ReallyDo Numeric;
Begin
Select Case Upper(Datepart)
When 'YYYY' Then
Trunc(Extract(Year From CDate(EndDate)) -
Extract(Year From CDate(StartDate)))
When 'M' Then
Datediff('YYYY', StartDate, EndDate) * 12 +
(Extract(Month From CDate(EndDate)) -
Extract(Month From CDate(StartDate)))
When 'D' Then
Trunc(CDate(EndDate) - CDate(StartDate))
When 'H' Then
Datediff('D', StartDate, EndDate) * 24 +
(to_Number(to_char(CDateTime(EndDate), 'HH24')) -
to_Number(to_char(CDateTime(StartDate), 'HH24')))
When 'N' Then
Datediff('D', StartDate, EndDate) * 24 * 60 +
(to_Number(to_char(CDateTime(EndDate), 'MI')) -
to_Number(to_char(CDateTime(StartDate), 'MI')))
When 'S' Then
Datediff('D', StartDate, EndDate) * 24 * 60 * 60 +
(to_Number(to_char(CDateTime(EndDate), 'SS')) -
to_Number(to_char(CDateTime(StartDate), 'SS')))
Else
-29252888
End
Into ReallyDo
From Dual;
Return(ReallyDo);
End Datediff;
備注：oracle中利用日期間的加減運(yùn)算如下
天：
ROUND(TO_NUMBER(END_DATE - START_DATE))
小時(shí)：
ROUND(TO_NUMBER(END_DATE - START_DATE) * 24)
分鐘：
ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60)
秒：
ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60 * 60)
