How to check missed schedules of custom scheduler?

Question

Hello,
I have created a custom scheduler that has been running fine, but it depends on SQL Server Agent service. I want it to process missed schedules after a potential downtime.
CREATE TABLE [dbo].[Schedules](
[Id] [int] NOT NULL,
[Frequency] [int] NOT NULL,
[Time] [time](0) NOT NULL,
[Days] [int] NOT NULL
) ON [PRIMARY]
GO
INSERT INTO Schedules VALUES (1,1,'01:00:00',16);
INSERT INTO Schedules VALUES (2,1,'23:30:00',62);
INSERT INTO Schedules VALUES (3,1,'18:00:00',127);
INSERT INTO Schedules VALUES (4,2,'01:00:00',16);
INSERT INTO Schedules VALUES (5,2,'02:30:00',8);
INSERT INTO Schedules VALUES (6,2,'23:30:00',127);
GO
The following is the query I run every minute to capture the schedules to run at that minute.
DECLARE @dt datetime,
@tm time(0),
@wd int;
SELECT @dt = CONVERT(char(16),Getdate(),121); --Zero out seconds and milliseconds
--SELECT @dt = CONVERT(char(16),'2014-02-25 09:39:25.443',121);
SELECT @tm = CAST(@dt as time(0));
SELECT @wd = DATEPART(weekday,@dt) -1; -- Sunday=0, Monday=1,...,Saturday=6
SELECT Id, Frequency, Time, Days
FROM Schedules
WHERE
(frequency = 2 --Daily
AND days & power(2,@wd) <> 0
AND datepart(hour,time) = datepart(hour,@tm)
AND datepart(minute,time) = datepart(minute,@tm))
OR
(frequency = 1 --Hourly
AND datepart(minute,time) = datepart(minute,@tm));
Now, I need to create a query/sproc which will returns schedule ids between two dates. I will populate the dates; the datetime of last executed schedule (id) as @StartDate, and maybe GetDate() as @EndDate. I can later run that sproc as a strtup sproc for
SQL Agent service.
usp_FindMissedSchedules @StartDate, @EndDate;
No simple approach comes to my mind.
Thanks,
Kuzey

Answer 1

You can do this by creating a CTE that will include one row for every minute of every day between @StartDate and EndDate and then cross joining it to your Schedules table.  So
Declare @StartDate datetime = '20140218 10:07';
Declare @EndDate datetime = GetDate();
With cte As
(Select DateAdd(minute, 1, @StartDate) As EachMinute
Union All
Select DateAdd(minute, 1, c.EachMinute) As EachMinute
From cte c
Where c.EachMinute < GetDate())
Select s.Id, s.Frequency, s.Time, s.Days, c.EachMinute As ShouldHaveBeenRunAt
From cte c
Cross Join dbo.Schedules s
WHERE
(frequency = 2 --Daily
AND days & power(2,DateDiff(day, '18991231' /* because Dec 31, 1899 was a Sunday */, c.EachMinute) % 7) <> 0
AND datepart(hour,time) = datepart(hour,c.EachMinute)
AND datepart(minute,time) = datepart(minute,c.EachMinute))
OR
(frequency = 1 --Hourly
AND datepart(minute,time) = datepart(minute,c.EachMinute))
Order By c.EachMinute, s.Id
Option(MaxRecursion 0);
I used a different method to determine Sunday = 0, Monday = 1, etc.  It can be problematic to use DATEPART(weekday ...) to determine the day of the week.  The value returned by DATEPART depends on the value of DATEFIRST.  And the default value
of DATEFIRST depends on the language set on the user's PC.  If someone who has a PC set up as English UK runs DATEPART(weekday...) for a Saturday date, they don't get 7 as the result, they get 6.
A safe way to the Sunday = 0, Monday = 1, etc is to do DateDiff(days, ...), divide by 7 and take the remainder (that"s what the % 7 does in the above code) where you use a date that is a Sunday.  This is what I did in the code above.  You can pick
any Sunday, I choose Dec 31, 1899.  That way your code works no matter what the value of DATEFIRST is.
Tom