Re: Calculation of Leap Year

ats wrote:
>
> Walt wrote:
>
> > ats wrote:
> >
> >>Satish wrote:
> >
> >
> >>>IS there any way in PL/SQL to identify an year as a Leap Year?
> >
> >
> >>CREATE OR REPLACE FUNCTION is_leap_year (yearstr VARCHAR2)
> >>RETURN BOOLEAN IS
> >>
> >>d DATE;
> >>
> >>BEGIN
> >> d := TO_DATE('29-FEB-' || yearstr);
> >> RETURN TRUE;
> >>EXCEPTION
> >> WHEN OTHERS THEN
> >> RETURN FALSE;
> >>END;
> >>/
> >
> >
> >
> > I'd write it as d := TO_DATE('29-FEB-' || yearstr, 'dd=MON-yyyy');
> >
> > That way it won't break if someone changes the default date format.
>
> Good observation. Thanks.
>
> --
> Daniel A. Morgan
> University of Washington
> damorgan_at_x.washington.edu
> (replace 'x' with 'u' to respond)

I can't remember if my algorithm is correct, but avoiding the data type conversion might be more efficient...

SQL> create or replace
  2 function f1(y number) return boolean is   3 x date;
  4 begin
  5 x := to_date('2902'||y,'ddmmyyyy');   6 return true;
  7 exception
  8 when others then return false;
  9 end;
 10 /

Function created.

SQL> create or replace
  2 function f2(y number) return boolean is   3 begin
  4 return mod(y,4)=0 and ( mod(y,100) != 0 or mod(y,400) = 0 );   5 end;
  6 /

Function created.

SQL> set timing on
SQL> declare
  2 l boolean;
  3 begin
  4 for i in 1 .. 500000 loop
  5 l := f1(1234);
  6 end loop;
  7 end;
  8 /

PL/SQL procedure successfully completed.

Elapsed: 00:00:06.96
SQL> declare
  2 l boolean;
  3 begin
  4 for i in 1 .. 500000 loop
  5 l := f2(1234);
  6 end loop;
  7 end;
  8 /

PL/SQL procedure successfully completed.

Elapsed: 00:00:01.09

Cheers
Connor

-- 
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
ISBN: 1590592174

web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com

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