Question

I have some events in a MySQL database and I need to extract them to feed a calendar. Normal events are not a problem but I have some special events that could repeat on a yearly basis. My problem is how to extract these events. I tried this to get events in the interval [$ini_month, $ini_day] – [$end_month, $end_day]:

SELECT * FROM `events` 
WHERE `repeat`='1' AND 
    MONTH(`date`) BETWEEN '$ini_month' AND '$end_month' AND 
    DAY(`date`) BETWEEN '$ini_day' AND '$end_day'

For instance, if I have to get events from July 1st to July 7th, $ini_month=$end_month=7, $ini_day=1 and $end_day=7. In this case this query works, but if I have to get events from June 25th to July 7th it fails $end_day < $ini_day. So, please, could you help me to generalize this query to make it work against any input?

Answer 1

You have to treat the “boder months” specially.

SELECT * FROM `events` 
WHERE `repeat`='1' AND 
    MONTH(`date`) BETWEEN '$ini_month+1' AND '$end_month-1' OR 
    (MONTH(`date`) == $ini_month AND DAY(`date`) > '$ini_day') OR
    (MONTH(`date`) == $end_month AND DAY(`date`) < '$end_day')

should work. But this is extremely ugly.

Instead, you could do something like

WHERE `repeat`='1' AND 
    MONTH(`date`) * 100 + DAY(`date`) BETWEEN $ini_month_day AND $end_month_day

if you set $ini_month_day and $end_month_day to appropriate values.

Be aware that this isn’t optimal as well, as you cannot use indexes this way.