How do I check whether the time has reached the next half hour in SQL? - sql

Question

I know, confusing title. Let me explain:
I have a job that has multiple steps.
The job runs every 15 minutes.
One of the steps in the job is to run a check (stored procedure) to see if there are records in a temp table that is created inside that stored procedure.
If there are records, I want to send an email.
The email can only be sent between 7am and 4pm and it'll repeat every 30 minutes.
Right now, I know how to check whether something exists and it's in the right time frame:
IF (EXISTS ( SELECT 1
FROM #NewItems
WHERE DATEPART(HOUR, GETDATE()) BETWEEN 7 AND 16 ))
BEGIN
-- send email
END
So my question is, how do I do the above check AND it's the next half hour?
For example, I want to send this email at 7am, 7:30am, 8am, 8:30am, etc. until 16:00 (or 4pm).
How would I go about doing this?

Answer 1

You could use an audit table to keep track of the emails that you've sent. Something like:
CREATE TABLE EMAIL_AUDIT_TRAIL
(
EMAIL_SEND_TIME AS DATETIME NOT NULL,
EMAIL_SUMMARY AS VARCHAR(100)
)
A benefit of this is that you get some traceability on the server side to say when emails were sent, and maybe a short summary of what they said (like number of items or whatever).
Each time the stored procedure runs, you could round the current time to the last 30 minute interval using something like CAST(FLOOR(CAST(GETDATE() as FLOAT(53))*48)/(48) AS DATETIME) (adapted from an answer on the question T-SQL: Round to nearest 15 minute interval), and then check to see if that interval has an entry in the audit table.
If it does not, send the email (and add the appropriate entry to the audit table).
You could even use the same approach to determine if the interval was one that should have an email sent by checking whether the current time (rounded to the nearest 30 minutes) is contained within a table containing all of the times during the day that should have emails sent (so in your case, all 30 minute intervals between 7:00 and 16:00).
Obviously you'd have to include some cleanup of the audit table to make sure it doesn't grow forever as well.