This is a not-quite complete implementation of the SY/MS sql datediff. The
months_between function can be extrapolated from it as well. I looked for
it on forums, etc. and all I found were people complaining about the lack of
an example. Please post fixes/changes or a link to a better one... if you
know of it.
CREATE OR REPLACE FUNCTION public.datediff(varchar, timestamp, timestamp) RETURNS int4 AS
'
DECLAREarg_mode alias for $1;arg_d2 alias for $2;arg_d1 alias for $3;
BEGIN
if arg_mode = \'dd\' or arg_mode = \'d\' or arg_mode = \'y\' or arg_mode =
\'dy\' or arg_mode = \'w\' thenreturn cast(arg_d1 as date) - cast(arg_d2 as date);
elsif arg_mode = \'ww\' then return ceil( ( cast(arg_d1 as date) - cast(arg_d2 as date) ) / 7.0);
elsif arg_mode = \'mm\' OR arg_mode = \'m\' thenreturn 12 * (date_part(\'year\',arg_d1) - date_part(\'year\',arg_d2))
+ date_part(\'month\',arg_d1) - date_part(\'month\',arg_d2) + case when date_part(\'day\',arg_d1) >
date_part(\'day\',arg_d2) then 0 when date_part(\'day\',arg_d1) =
date_part(\'day\',arg_d2) and cast(arg_d1 as time) >= cast(arg_d2 as time) then 0
else-1 end;
elsif arg_mode = \'yy\' OR arg_mode = \'y\' OR arg_mode = \'yyyy\' thenreturn (cast(arg_d1 as date) - cast(arg_d2 as
date))/ 365;
end if;
END;
' LANGUAGE 'plpgsql' VOLATILE;
