Solved

MSSQL Datediff for time slot scheduling

Posted on 2009-06-30
2
690 Views
Last Modified: 2012-05-07
I am in making a process for class registration. Each class has a corresponding time slot id, of which has a timeslotstart and timeslotend column. Currently they are varchar values since they only are hour & minute time slots. My issue is, when a person signs up for a class in timeslotid 2, starttime being 10 am endtime being 11am, I need to be able to remove other classes from the selection that have a starttime or endtime that is between those dates. I have something that sort of works below, but I am hoping to find something a little better. With the example below, it works for all entries except for ID 13, which has a start time of 9AM and end time of 17PM(5PM).
---------query
SELECT timeslotid, 
datepart(hh, convert(smalldatetime, timeslotstart, 14)) as StartTime, 
convert(smalldatetime, timeslotend, 14) as EndTime,
CASE 
WHEN datepart(hh, convert(smalldatetime, timeslotstart, 14)) 
between 
(SELECT datepart(hh, convert(smalldatetime, timeslotstart, 14)) 
from dbo.TimeSlots WHERE TimeSlotID = 2)
and 
(SELECT datepart(hh, convert(smalldatetime, timeslotend, 14))from dbo.TimeSlots WHERE TimeSlotID = 2)
THEN 'NOT'
ELSE 'SO'
END as StartTime,
CASE 
WHEN convert(smalldatetime, timeslotend, 14) 
between 
(SELECT  convert(smalldatetime, timeslotstart, 14) 
from dbo.TimeSlots WHERE TimeSlotID = 2)
and 
(SELECT convert(smalldatetime, timeslotend, 14)from dbo.TimeSlots WHERE TimeSlotID = 2)
THEN 'NOT'
ELSE 'SO'
END as Endtime
from dbo.timeslots
 
 
----results   bs= between start       be=between end
timeID		start			end		bs	be
1		9		1900-01-01 10:00:00	SO	NOT
2		10		1900-01-01 11:00:00	NOT	NOT
3		11		1900-01-01 12:00:00	NOT	SO
4		14		1900-01-01 15:00:00	SO	SO
5		15		1900-01-01 16:00:00	SO	SO
6		16		1900-01-01 17:00:00	SO	SO
7		9		1900-01-01 10:30:00	SO	NOT
8		9		1900-01-01 11:00:00	SO	NOT
9		10		1900-01-01 12:00:00	NOT	SO
10		10		1900-01-01 11:30:00	NOT	SO
11		14		1900-01-01 15:30:00	SO	SO
12		14		1900-01-01 16:00:00	SO	SO
13		9		1900-01-01 17:00:00	SO	SO
14		10		1900-01-01 12:00:00	NOT	SO

Open in new window

0
Comment
Question by:GLIanimal
2 Comments
 
LVL 59

Accepted Solution

by:
Kevin Cross earned 500 total points
ID: 24746127
Try something like this:
+Uses a common table expression to simplify tests requiring the start and end times as datetime data type (could use view or do conversions in line).
+Filter records to time slots not equal to one already selected, in your case id #2.
+Apply or join in the data for the time slot that is selected (#2).
+Test that start is not between start and end time of selected record; however, since can start a class right as one ends backoff the endtime by a minute since between is inclusive.
+Repeat test for end time with offset to start of next class.
+Repeat with opposite side as current class may be much longer and span over already selected class.
with timeslotCTE AS (
	select timeslotid
	, cast(start as datetime) as StartTime
	, cast([end] as datetime) as EndTime
	from timeslots
) select t1.timeslotid
, convert(varchar, t1.starttime, 108) as StartTime
, convert(varchar, t1.endtime, 108) as EndTime
from timeslotCTE t1
cross apply (select starttime, endtime from timeslotCTE where timeslotid = 2) t2
where t1.timeslotid <> 2
	and t1.starttime not between t2.starttime and dateadd(mi, -1, t2.endtime)
	and t1.endtime not between dateadd(mi, +1, t2.starttime) and t2.endtime
	and t2.starttime not between t1.starttime and dateadd(mi, -1, t1.endtime)
	and t2.endtime not between dateadd(mi, +1, t1.starttime) and t1.endtime
;

Open in new window

0
 

Author Closing Comment

by:GLIanimal
ID: 31598338
Had to add IN and count for multiple values, but all in all thanks!
0

Featured Post

NAS Cloud Backup Strategies

This article explains backup scenarios when using network storage. We review the so-called “3-2-1 strategy” and summarize the methods you can use to send NAS data to the cloud

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
spx for moving values to new table 5 74
Bubble user-defined Sql RAISERROR(...) to c# exception 14 189
Sql query 107 73
SQL query with cast 38 53
I've encountered valid database schemas that do not have a primary key.  For example, I use LogParser from Microsoft to push IIS logs into a SQL database table for processing and analysis.  However, occasionally due to user error or a scheduled task…
In this article I will describe the Copy Database Wizard method as one possible migration process and I will add the extra tasks needed for an upgrade when and where is applied so it will cover all.
Microsoft Active Directory, the widely used IT infrastructure, is known for its high risk of credential theft. The best way to test your Active Directory’s vulnerabilities to pass-the-ticket, pass-the-hash, privilege escalation, and malware attacks …

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question