Extract day of week (i.e. 'saturday') from date field - HQL - sql

Question

I have a date field in a hive table following this format:
'YYYY-MM-DD'
I'm looking for a function (let's call this yet-to-be-discovered-by-me function dayofweek()) that will return 'friday' when run on today's date. So, to be explicitly clear, this query:
SELECT DAYOFWEEK(DT.ds), DT.ds
FROM dateTable DT
WHERE DT.ds = '2014-11-14'
LIMIT 1
would return this value:
'friday' '2014-11-14'
Any help would be greatly appreciated :) google searching as of yet unfruitful.
Clark
P.S. The response to this question did not work for me...error returned: 'Invalid function 'dayofweek''

Answer 1

Should you care for an equation, following is C code hopefully simple enough to translate into SQL.
Important to use integer math.
#define MARCH 3
int dow_Sunday0(int year, int month, int day) {
if (month < MARCH) {
month += 12;
year--;
}
// Add days for each year and leap years
day += year + year/4 - year/100 + year/400;
// add days for the month
day += month*30 + ((month-MARCH)*39 + 25)/64;
// modulo 7
return (day+3)%7;
}
This works for valid Gregorian calendar dates.

Answer 2

Use DAYNAME() function, like this:
mysql> select dayname('2014-11-14');
+-----------------------+
| dayname('2014-11-14') |
+-----------------------+
| Friday |
+-----------------------+
1 row in set (0.00 sec)
So, your query will become:
SELECT DAYNAME(DT.ds), DT.ds
FROM dateTable DT
WHERE DT.ds = '2014-11-14'
LIMIT 1