Question

I’m working on a system to store appointments and recurring appointments. My schema looks like this

Appointment
-----------
ID
Start
End
Title
RecurringType
RecurringEnd

RecurringTypes
---------------
Id
Name

I’ve keeped the Recurring Types simple and only support

Week Days,
Weekly,
4 Weekly,
52 Weekly

If RecurringType is null then that appointment does not recur, RecurringEnd is also nullable and if its null but RecurringType is a value then it will recur indefinatly. I’m trying to write a stored procedure to return all appointments and their dates for a given date range.

I’ve got the stored procedure working for non recurring meetings but am struggling to work out the best way to return the recurrences this is what I have so far

ALTER PROCEDURE GetAppointments
(
    @StartDate DATETIME,
    @EndDate DATETIME
)
AS

SELECT  
    appointment.id,
    appointment.title,
    appointment.recurringType,
    appointment.recurringEnd,
    appointment.start,
    appointment.[end]
FROM
    mrm_booking
WHERE
    (
        Start >= @StartDate AND
        [End] <= @EndDate
    ) 

I now need to add in the where clauses to also pick up the recurrences and alter what is returned in the select to return the Start and End Dates for normal meetings and the calculated start/end dates for the recurrences.

Any pointers on the best way to handle this would be great. I’m using SQL Server 2005

Answer 1

I ended up doing this by creating a temp table of everyday between the start and end date along with their respective day of the week. I limited the recurrence intervals to weekdays and a set amount of weeks and added where clauses like this

        --Check Week Days Reoccurrence
        (
            mrm_booking.repeat_type_id = 1 AND              
            #ValidWeeklyDayOfWeeks.dow IN (1,2,3,4,5)
        ) OR
        --Check Weekly Reoccurrence
        (
            mrm_booking.repeat_type_id = 2 AND
            DATEPART(WEEKDAY, mrm_booking.start_date) = #ValidWeeklyDayOfWeeks.dow
        ) OR
        --Check 4 Weekly Reoccurences
        (
            mrm_booking.repeat_type_id = 3 AND
            DATEDIFF(d,#ValidWeeklyDayOfWeeks.[Date],mrm_booking.start_date) % (7*4) = 0
        ) OR
        --Check 52 Weekly Reoccurences
        (
            mrm_booking.repeat_type_id = 4 AND
            DATEDIFF(d,#ValidWeeklyDayOfWeeks.[Date],mrm_booking.start_date) % (7*52) = 0
        )

In case your interested I built up a table of the days between the start and end date using this

INSERT INTO #ValidWeeklyDayOfWeeks
--Get Valid Reoccurence Dates For Week Day Reoccurences
SELECT
    DATEADD(d, offset - 1, @StartDate) AS [Date],
    DATEPART(WEEKDAY,DATEADD(d, offset - 1, @StartDate)) AS Dow
FROM
    (
        SELECT ROW_NUMBER() OVER(ORDER BY s1.id) AS offset
        FROM syscolumns s1, syscolumns s2
    ) a WHERE offset <= DATEDIFF(d, @StartDate, DATEADD(d,1,@EndDate)) 

Its not very elegant and probably very specific to my needs but it does the job I needed it to do.