Determine if Oracle date is on a weekend?

问题:

Is this the best way to determine if an Oracle date is on a weekend?

select * from mytable
where 
TO_CHAR (my_date, 'DY', 'NLS_DATE_LANGUAGE=ENGLISH') IN ('SAT', 'SUN');

回答1:

As of Oracle 11g, yes. The only viable region agnostic alternative that I've seen is as follows:

SELECT *
FROM mytable
WHERE MOD(TO_CHAR(my_date, 'J'), 7) + 1 IN (6, 7);

回答2:

Not an answer to the question. But some more information. There are many more SQL tricks with date.

to_char(sysdate, 'd') --- day of a week, 1,2,3 .. to 7
to_char(sysdate, 'dd') --- day of a month, 1,2,3 .. to 30 or 31
to_char(sysdate, 'ddd') --- day of a year, 1,2,3 .. to 365 or 366
to_char(sysdate, 'w') --- week of a month, 1,2,3,4 or 5
to_char(sysdate, 'ww') --- week of a year, 1,2,3 .. to 52

More here: to_char function.

回答3:

MOD(TO_CHAR(my_date, 'J'), 7) + 1 IN (6, 7)

is NOT correct! The day number of weekend days may be 6 & 7, or 7 and 1, depending on the NLS-settings.

So the PROPER test (irrespective of NLS-settings) is this one mentioned before:

TO_CHAR (my_date, 'DY', 'NLS_DATE_LANGUAGE=ENGLISH') IN ('SAT', 'SUN')

回答4:

set NLS_TERRITORY before

alter session set NLS_TERRITORY=SWEDEN;

So you are sure which numbers are weekends

回答5:

In my opinion the best option is

TO_CHAR (my_date, 'DY', 'NLS_DATE_LANGUAGE=ENGLISH') IN ('SAT', 'SUN')