How do I find the next saturday in MySQL

I have trigger and a stored procedure in it (so SP runs when trigger runs). I need a function which finds the next saturday to put in SP.

So lets say, it is Wednesday (2015-7-22) today. If my trigger runs today, the SP in it must find the next Saturday (2015-7-25).

Plus, even if it is Saturday, but the time is earlier of 9.30 pm, it must find the current day also. After 9.30 pm, it must return the next Saturday.

I would like to the put my whole trigger and sp on here but I don't want to get here crowded. I just need ideas, thanks.

EDIT:

Thanks to oNaye, I coded that:

CREATE DEFINER=`root`@`localhost` PROCEDURE `newGuess`(
IN `muserID` INT, 
IN `numm1` INT, 
IN `numm2` INT, 
IN `numm3` INT, 
IN `numm4` INT, 
IN `numm5` INT, 
IN `numm6` INT)
    begin
set @today = (select weekday(curdate())+1); /*monday is the first day in here*/
if @today=5,(6-WEEKDAY(NOW())),(5-WEEKDAY(NOW()))) DAY));
end if;
if @today = 6 then /* it is saturday */
    set @current_time = (select curtime());
    set @nextSaturday = (SELECT DATE_ADD(NOW(),INTERVAL IF(WEEKDAY(NOW())>=5,(6-WEEKDAY(NOW())),(5-WEEKDAY(NOW()))) DAY));
    if @current_time =CAST('21:30:00' AS time) then
        set @nextSaturday = curdate()+INTERVAL 1 WEEK;
    end if;
end if;
insert into guessesTBL (userID,num1,num2,num3,num4,num5,num6,current__datetime,draw_date) values (muserID,numm1,numm2,numm3,numm4,numm5,numm6,NOW(),@nextSaturday);

end

It worked now.
Solved.

You can use WEEKDAY and DATE_ADD function to calculate the next weekday incoming.

Here what you have to do:

SELECT 
  DATE_ADD(NOW(),INTERVAL IF(WEEKDAY(NOW())>=5,
                             (6-WEEKDAY(NOW())),
                             (5-WEEKDAY(NOW()))) DAY);

The query meaning:

With DATE_ADD you will add an interval between the parameter NOW() and one condition assuming my weekday for Saturday is 5, you will have to evaluate if NOW() is greater than 5 or equal, you have to rest it with 6 (Sunday) and if NOW() is less than 5 you have to rest it 5 with the weekday of NOW().

Test:

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2015-07-22 07:51:33 |
+---------------------+
1 row in set (0.00 sec)

mysql> SELECT DATE_ADD(NOW(),INTERVAL IF(WEEKDAY(NOW())>=5,(6-WEEKDAY(NOW())),(5-WEEKDAY(NOW()))) DAY);
+------------------------------------------------------------------------------------------+
| DATE_ADD(NOW(),INTERVAL IF(WEEKDAY(NOW())>=5,(6-WEEKDAY(NOW())),(5-WEEKDAY(NOW()))) DAY) |
+------------------------------------------------------------------------------------------+
| 2015-07-25 07:51:34                                                                      |
+------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

EDIT:

If you need to calculate to get the next Saturday if the actual Saturday is at 9:30PM:

New syntax:

SET @ACTUAL_DATE=NOW();
SET @NEXT_SATURDAY=DATE_ADD(@ACTUAL_DATE,INTERVAL IF(WEEKDAY(@ACTUAL_DATE)=5 && TIME(@ACTUAL_DATE)>'21:30:00',
                                            7,
                                            IF(WEEKDAY(@ACTUAL_DATE)>=5,
                                                (6-WEEKDAY(@ACTUAL_DATE)),
                                                (5-WEEKDAY(@ACTUAL_DATE)))) 
                                        DAY);

Today test:

mysql> SET @ACTUAL_DATE=NOW();
Query OK, 0 rows affected (0.01 sec)

mysql> SET @NEXT_SATURDAY=DATE_ADD(@ACTUAL_DATE,INTERVAL IF(WEEKDAY(@ACTUAL_DATE)=5 && TIME(@ACTUAL_DATE)>'21:30:00',
    -> 7,
    -> IF(WEEKDAY(@ACTUAL_DATE)>=5,
    -> (6-WEEKDAY(@ACTUAL_DATE)),
    -> (5-WEEKDAY(@ACTUAL_DATE)))) 
    -> DAY);
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @NEXT_SATURDAY;
+---------------------+
| @NEXT_SATURDAY      |
+---------------------+
| 2015-07-25 21:30:01 |
+---------------------+
1 row in set (0.00 sec)

mysql>

But if we're on July 25th at 21:30:01 (Saturday):

mysql> SET @ACTUAL_DATE='2015-07-25 21:30:01';
Query OK, 0 rows affected (0.00 sec)

mysql> SET @NEXT_SATURDAY=DATE_ADD(@ACTUAL_DATE,INTERVAL IF(WEEKDAY(@ACTUAL_DATE)=5 && TIME(@ACTUAL_DATE)>'21:30:00',
    -> 7,
    -> IF(WEEKDAY(@ACTUAL_DATE)>=5,
    -> (6-WEEKDAY(@ACTUAL_DATE)),
    -> (5-WEEKDAY(@ACTUAL_DATE)))) 
    -> DAY);
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @NEXT_SATURDAY;
+---------------------+
| @NEXT_SATURDAY      |
+---------------------+
| 2015-08-01 21:30:01 |
+---------------------+
1 row in set (0.00 sec)

StackExchange Database Administrators Q#107744, answer score: 10