问题
I have a table in mysql like this:
+------------+------------+------------+------------+
| date | user_id | start_hour | end_hour |
+------------+------------+------------+------------+
| 2010-12-15 | 20 | 08:00:00 | 08:15:00 |
| 2010-12-15 | 20 | 14:00:00 | 14:30:00 |
| 2010-12-15 | 20 | 17:00:00 | 17:45:00 |
+------------+------------+------------+------------+
and I try to extract the time range of the time of users I found and example here, but I can't make that work on hours
I tried the query:
$sql="
SELECT a.end_hour AS 'Available From', Min(b.start_hour) AS 'To'
FROM (
SELECT 0 as date, '08:00:00' as start_hour,'08:00:00' as end_hour
UNION SELECT date, start_hour, end_hour FROM table
)
AS a JOIN
( SELECT date, start_hour, end_hour FROM table
UNION SELECT 0, '21:00:00' as start_hour, '22:00:00' as end_hour
) AS b ON
a.date=b.date AND a.user_id=b.user_id AND a.end_hour < b.start_hour WHERE
a.date='$date' AND a.user_id='$user_id' GROUP BY a.end_hour
HAVING a.end_hour < Min(b.start_hour);";
I need to create a range since 08:00 to 21:00 with the free blocks between the appointments like this:
free time
08:15:00 to 14:00:00
14:30:00 to 17:00:00
17:45:00 to 21:00:00
回答1:
Try this query
SELECT
a.id,
a.start_hour,
a.end_hour,
TIMEDIFF(la.start_hour, a.end_hour) as `Free Time`
FROM appointment as a
LEFT JOIN(SELECT * FROM appointment LIMIT 1,18446744073709551615) AS la
ON la.id = a.id + 1
LEFT JOIN (SELECT * FROM appointment) AS ra ON a.id = ra.id
This will show these results
+---------------------------------------------+
¦ id ¦ start_hour BY ¦ end_hour | Free Time |
¦----+---------------¦------------------------|
¦ 1 ¦ 08:00:00 ¦ 08:15:00 | 05:45:00 |
¦ 2 ¦ 14:00:00 ¦ 14:30:00 | 02:30:00 |
¦ 3 ¦ 17:00:00 ¦ 17:45:00 | 03:15:00 |
¦ 4 ¦ 21:00:00 ¦ 21:00:00 | (NULL) |
+--------------------+------------------------+
Also you must have the 21:00:00 in the table or you wont be able to get the last time difference. i entered 21:00:00 as start and end date in the table.
EDITED
This is modified query
SELECT
a.id,
a.end_hour AS `Free time Start`,
IFNULL(la.start_hour,a.end_hour) AS `Free Time End`,
IFNULL(TIMEDIFF(la.start_hour, a.end_hour),'00:00:00') AS `Total Free Time`
FROM appointment AS a
LEFT JOIN (SELECT * FROM appointment LIMIT 1,18446744073709551615) AS la
ON la.id = (SELECT MIN(id) FROM appointment where id > a.id LIMIT 1)
And the result is
+--------------------------------------------------------+
¦ id ¦ Free time Start ¦ Free Time End | Total Free Time |
¦----+-----------------¦---------------------------------|
¦ 1 ¦ 08:15:00 ¦ 14:00:00 | 05:45:00 |
¦ 2 ¦ 14:30:00 ¦ 17:00:00 | 02:30:00 |
¦ 3 ¦ 17:45:00 ¦ 21:00:00 | 03:15:00 |
¦ 4 ¦ 21:00:00 ¦ 21:00:00 | 00:00:00 |
+----------------------+---------------------------------+
The points to learn from this query are
- Timediff function usage. timediff('end time','start time')
- Joining with upper number
- Avoid first record in join with a long offset and limit starting from 1 instead of zero
- IFNULL usage ifnull('if here comes null','select this then')
回答2:
Try this Query i hope its work for you.....
SELECT
a.id,
a.end_hour AS `Free time Start`,
la.start_hour AS `Free Time End`,
IFNULL(TIMEDIFF(la.start_hour, a.end_hour),'00:00:00') AS `Total Free Time`
FROM appointment AS a
LEFT JOIN (SELECT *
FROM appointment
LIMIT 1,18446744073709551615) AS la
ON la.id = (SELECT
id
FROM appointment
WHERE id NOT IN(a.id)
ORDER BY (a.id > id)ASC
LIMIT 1);
回答3:
This will give you the end time blocks
SELECT T_a.end_hour
FROM (table AS T_a) LEFT JOIN (table AS T_b)
ON (T_a.`date`=T_b.`date` AND T_b.start_hour<=T_a.end_hour AND T_b.end_hour>T_a.end_hour)
WHERE T_b.user_id IS NULL
This will give you the start time block
SELECT T_a.start_hour
FROM (table AS T_a) LEFT JOIN (table AS T_b)
ON (T_a.`date`=T_b.`date` AND T_b.start_hour<T_a.start_hour AND T_b.end_hour>=T_a.start_hour)
WHERE T_b.user_id IS NULL
These queries will look for starts or ends that are uncrossed or butted up to other slots. so 10-11 11-12 will give 10 start, 12 end = free time is 08-10 and 12-21
So free time is 08:00 (unless its a start time) upto first 'start' time, then matching pairs of END->START upto last END->21:00 (unless 21:00 IS the last end)
N.B. You'll need to add the date in too.
回答4:
Perhaps this is over kill but this works on sql-server, not sure the effort to convert to mysql
declare @AvailableTime table ( AvailableDate date, StartTime time, EndTime time )
insert into @AvailableTime values
('15 dec 2010', '08:00:00', '21:00:00')
declare @Booking table (BookingDate date, UserId int, StartTime Time, EndTime Time)
insert into @Booking values
('15 dec 2010', 20, '08:00:00', '08:15:00'),
('15 dec 2010', 20, '14:00:00', '14:30:00'),
('15 dec 2010', 20, '17:00:00', '17:45:00')
select
*
from
(
-- first SELECT get start boundry
select t.StartTime s, b.StartTime e
from @AvailableTime t, @Booking b
where
t.AvailableDate = b.BookingDate and (t.StartTime <= b.EndTime and b.StartTime <= t.EndTime) and t.StartTime <> b.StartTime
and
not exists (select 1 from @Booking b2 where b2.BookingDate = b.BookingDate and b2.StartTime < b.StartTime)
union
-- second SELECT get spikes ie middle
select b1.EndTime s, b2.StartTime e
from @AvailableTime t, @Booking b1, @Booking b2
where
t.AvailableDate = b1.BookingDate and (t.StartTime <= b1.EndTime and b1.StartTime <= t.EndTime)
and
t.AvailableDate = b2.BookingDate and (t.StartTime <= b2.EndTime and b2.StartTime <= t.EndTime)
and
b1.EndTime < b2.StartTime
and
not exists (select 1 from @Booking b3 where b3.BookingDate = t.AvailableDate and b3.StartTime > b1.EndTime and b3.EndTime < b2.StartTime)
union
-- third SELECT get end boundry
select b.EndTime s, t.EndTime e
from @AvailableTime t, @Booking b
where
t.AvailableDate = b.BookingDate and (t.StartTime <= b.EndTime and b.StartTime <= t.EndTime) and t.EndTime <> b.EndTime
and
not exists (select 1 from @Booking b2 where b2.BookingDate = b.BookingDate and b2.StartTime > b.StartTime)
) t1
来源：https://stackoverflow.com/questions/11262260/finding-free-blocks-of-time-in-mysql-and-php