Random Scheduling - sql

Question

I have the following table in my database:
tbl1
PK
ClientID
ScheduleDay
Time1Start
Time1Stop
Time2Start
Time2Stop
Time3Start
Time3Stop
Status
Here is some sample data
ID ClientID ScheduleDay Time1Start Time1Stop Time2Start Time2Stop Time3Start Time3Stop
-- -------- ----------- ---------- --------- ---------- --------- ---------- ---------
1 3 Sunday 0000 0800 1000 1300 NULL NULL
2 3 Monday 0000 2359 NULL NULL NULL NULL
3 3 Tuesday 1000 1200 1330 1700 1900 2200
4 3 Wednesday 0000 0800 NULL NULL NULL NULL
5 3 Thursday 0800 1200 NULL NULL NULL NULL
6 3 Friday 0400 0800 0900 1600 NULL NULL
The Time fields are CHAR(4) since I am storing the time in a military format.
What I need to accomplish is this; for any given ClientID, insert one or more records into a schedule table with the time value of the record being within the time frames in tbl1. For example, scheduling ClientID 3 on Tuesday, the time scheduled could be 1120.
In the event that multiple records need to be inserted, the times scheduled should not be any closer than one hour.
Any and all help is appreciated!

Answer 1

Here's my best guess as to what you're trying to do. The first two parts of the CTE are really just to get things into a form similar to what FlyingStreudel suggests. Ideally, you should change the database to match that format instead of doing this through CTEs. That will make this significantly simpler and is better for data integrity as well.
Next, I just get the distinct start times in hour increments. You could do that by joining to a Numbers table as well if you can't use CTEs (you didn't mention the version of SQL Server that you're using).
Finally, I grab one of those start times at random, using the RAND function and ROW_NUMBER. You'll want to set a good seed value for RAND().
;WITH TimesAsTimes AS
(
SELECT
ScheduleDay,
CAST(SUBSTRING(T1.Time1Start, 1, 2) + ':' + SUBSTRING(T1.Time1Start, 3, 2) AS TIME) AS time_start,
CAST(SUBSTRING(T1.Time1Stop, 1, 2) + ':' + SUBSTRING(T1.Time1Stop, 3, 2) AS TIME) AS time_stop
FROM
tbl1 T1
WHERE
T1.Time1Start IS NOT NULL
UNION ALL
SELECT
ScheduleDay,
CAST(SUBSTRING(T2.Time2Start, 1, 2) + ':' + SUBSTRING(T2.Time2Start, 3, 2) AS TIME) AS time_start,
CAST(SUBSTRING(T2.Time2Stop, 1, 2) + ':' + SUBSTRING(T2.Time2Stop, 3, 2) AS TIME) AS time_stop
FROM
tbl1 T2
WHERE
T2.Time2Start IS NOT NULL
UNION ALL
SELECT
ScheduleDay,
CAST(SUBSTRING(T3.Time3Start, 1, 2) + ':' + SUBSTRING(T3.Time3Start, 3, 2) AS TIME) AS time_start,
CAST(SUBSTRING(T3.Time3Stop, 1, 2) + ':' + SUBSTRING(T3.Time3Stop, 3, 2) AS TIME) AS time_stop
FROM
tbl1 T3
WHERE
T3.Time3Start IS NOT NULL
),
PossibleTimeStarts AS
(
SELECT
ScheduleDay,
time_start,
time_stop
FROM
TimesAsTimes TAT
UNION ALL
SELECT
ScheduleDay,
DATEADD(hh, 1, time_start) AS time_start,
time_stop
FROM
PossibleTimeStarts PTS
WHERE
DATEADD(hh, 1, time_start) <= DATEADD(hh, -1, PTS.time_stop)
),
PossibleTimesWithRowNums AS
(
SELECT
ScheduleDay,
time_start,
ROW_NUMBER() OVER(PARTITION BY ScheduleDay ORDER BY ScheduleDay, time_start) AS row_num,
COUNT(*) OVER(PARTITION BY ScheduleDay) AS num_rows
FROM
PossibleTimeStarts
)
SELECT
*
FROM
PossibleTimesWithRowNums
WHERE
row_num = FLOOR(RAND() * num_rows) + 1

Answer 2

First of all you may want to try a schema like
tbl_sched_avail
PK id INT
FK client_id INT
day INT (1-7)
avail_start varchar(4)
avail_end varchar(4)
This way you are not limited to a finite number of time fences.
As far as checking the schedules availability -
CREATE PROCEDURE sp_ins_sched
#start_time varchar(4),
#end_time varchar(4),
#client_id INT,
#day INT
AS
BEGIN
DECLARE #can_create BIT
SET #can_create = 0
DECLARE #fence_start INT
DECLARE #fence_end INT
--IS DESIRED TIME WITHIN FENCE FOR CLIENT
DECLARE c CURSOR FOR
SELECT avail_start, avail_end FROM tbl_sched_avail
WHERE client_id = #client_id
AND day = #day
OPEN c
FETCH NEXT FROM c
INTO #fence_start, #fence_end
WHILE ##FETCH_STATUS = 0 AND #can_create = 0
BEGIN
IF #start_time >= #fence_start AND #start_time < #fence_end
AND #end_time > #fence_start AND <= #fence_end
SET #can_create = 1
FETCH NEXT FROM c
INTO #fence_start, #fence_end
END
CLOSE c
DEALLOCATE c
IF #can_create = 1
BEGIN
--insert your schedule here
END
END
As far as the code for actually inserting the record I would need to know more about the tables in the database.