Thread: Time Difference
I have the following setup: appt=# select * from availability \g emp_id | date | start_time | end_time --------+------------+------------+---------- 1 | 2000-10-30 | 08:00:00 | 14:30:00 appt=# select * from appointments \g start_time | end_time | emp_id | cus_id | services | date ------------+----------+--------+--------+----------+------------ 09:00:00 | 11:30:00 | 1 | 2 | {1,2,3} | 2000-10-30 Now, what I would like to get is the following: start_time | end_time ------------+---------- 08:00:00 | 09:00:00 11:30:00 | 14:30:00 I'm trying to generate a result set of all the free time slots in availability by taking the difference of the two. I've so far been unable to generate anything that works. Is this possible? Mike -- Mike Erickson <mee@quidquam> http://www.quidquam.com/ "Hatred is the coward's revenge for being intimidated" - George Bernard Shaw
On Fri, Oct 27, 2000 at 04:13:13AM -0700, Mike E wrote: > I have the following setup: > > appt=# select * from availability \g > emp_id | date | start_time | end_time > --------+------------+------------+---------- > 1 | 2000-10-30 | 08:00:00 | 14:30:00 > > appt=# select * from appointments \g > start_time | end_time | emp_id | cus_id | services | date > ------------+----------+--------+--------+----------+------------ > 09:00:00 | 11:30:00 | 1 | 2 | {1,2,3} | 2000-10-30 > > Now, what I would like to get is the following: > > start_time | end_time > ------------+---------- > 08:00:00 | 09:00:00 > 11:30:00 | 14:30:00 > not sure about the exact syntax, but to give you an idea: select av.starttime as start_time,ap.starttime as end_time from availability av, appointments ap where av.emp_id=ap.emp_idand av.emp_id=1; Same concept for the second row and then use the union-feature of the select-command to join. hope this helps, peter -- mag. peter pilsl email: pilsl@goldfisch.at pgp-key available
On Fri, Oct 27, 2000 at 02:13:07PM +0200, Peter Pilsl wrote: > On Fri, Oct 27, 2000 at 04:13:13AM -0700, Mike E wrote: > > I have the following setup: > > > > appt=# select * from availability \g > > emp_id | date | start_time | end_time > > --------+------------+------------+---------- > > 1 | 2000-10-30 | 08:00:00 | 14:30:00 > > > > appt=# select * from appointments \g > > start_time | end_time | emp_id | cus_id | services | date > > ------------+----------+--------+--------+----------+------------ > > 09:00:00 | 11:30:00 | 1 | 2 | {1,2,3} | 2000-10-30 > > > > Now, what I would like to get is the following: > > > > start_time | end_time > > ------------+---------- > > 08:00:00 | 09:00:00 > > 11:30:00 | 14:30:00 > > > > not sure about the exact syntax, but to give you an idea: That was just an example. What I would like to do is for any given range of availabilty, take all the appointments, subtract/difference them out and get a result set of all the time slots that are left. Is this something that can be done in SQL, or will I have to pull all the relevant data out and do all the logic in my application? I will have a varying number of appointments on each day, which possibly more than one availability record as well. Thanks, Mike -- Mike Erickson <mee@quidquam> http://www.quidquam.com/ "Hatred is the coward's revenge for being intimidated" - George Bernard Shaw
From: "Mike E" <mee@quidquam.com> To: <pgsql-general@postgresql.org> Sent: Friday, October 27, 2000 12:13 PM Subject: [GENERAL] Time Difference > I have the following setup: > > appt=# select * from availability \g > emp_id | date | start_time | end_time > --------+------------+------------+---------- > 1 | 2000-10-30 | 08:00:00 | 14:30:00 > > appt=# select * from appointments \g > start_time | end_time | emp_id | cus_id | services | date > ------------+----------+--------+--------+----------+------------ > 09:00:00 | 11:30:00 | 1 | 2 | {1,2,3} | 2000-10-30 > > Now, what I would like to get is the following: > > start_time | end_time > ------------+---------- > 08:00:00 | 09:00:00 > 11:30:00 | 14:30:00 > > > Mike Thought this couldn't be done for a minute, but it can assuming you have non-overlapping appointments. I simplified to think about it: richardh=> select * from used; starts | ends --------+------ 2 | 3 5 | 6 9 | 12 richardh=> select a.ends as gapstart, b.starts as gapend from used a, used b where b.starts>a.ends and b.starts = ( select min(c.starts) from used c where c.starts>a.ends); gapstart | gapend ----------+-------- 3 | 5 6 | 9 So - we're looking for the gap between the end of "a" and start of "b" where "b" is the next used slot after "a". You'll need fake entries in used for the start and end of the day to handle the start/end of your availabilty period (or just fake it in your application). Not sure if you might want >= instead of > If you do have overlapping appointments, then this isn't going to help you, but I'm guessing you don't. HTH - Richard Huxton