jvoconnell
asked on
determine if date is consecutive by person ID
Experts,
I have a table with a member id and an eligibility date. I need to create a record by member id with the minimum eligibility date and max eligibility date where the dates are consecutive (by month). The logic is also that there can be be a one month gap to be considered "consecutive". When the dates aren't consecutive, it would be a new record.
MemberID EligibilityDT
--------------------------
XYZ 1/1/2014
XYZ 2/1/2014
XYZ 4/1/2014
XYZ 7/1/2014
The desired output would be:
MemberID StartDT EndDT
--------------------------
XYZ 1/1/2014 4/1/2014
XYZ 7/1/2014 7/1/2014
My logic is cursor processing. I am looping thru by member and comparing a date variable to the next date variable by DateDiff. Then swithcing the value of the date variable vs. the next date.
Am I even correct that cursor processing is the way to go. It just seems like there has to be an easier way.
The table has 10M rows. Any insight is appreciated.
SQL Server 2012 if that matters.
Thank you.
I have a table with a member id and an eligibility date. I need to create a record by member id with the minimum eligibility date and max eligibility date where the dates are consecutive (by month). The logic is also that there can be be a one month gap to be considered "consecutive". When the dates aren't consecutive, it would be a new record.
MemberID EligibilityDT
--------------------------
XYZ 1/1/2014
XYZ 2/1/2014
XYZ 4/1/2014
XYZ 7/1/2014
The desired output would be:
MemberID StartDT EndDT
--------------------------
XYZ 1/1/2014 4/1/2014
XYZ 7/1/2014 7/1/2014
My logic is cursor processing. I am looping thru by member and comparing a date variable to the next date variable by DateDiff. Then swithcing the value of the date variable vs. the next date.
Am I even correct that cursor processing is the way to go. It just seems like there has to be an easier way.
The table has 10M rows. Any insight is appreciated.
SQL Server 2012 if that matters.
Thank you.
PortletPaul
SQL Server 2012 if that matters = thank you, thank you, thank you - knowing version is always important
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ASKER
Wow! This is great. I new I was attacking this the wrong way. Thank you so much!! Thank you both for jumping in.
Thanks for that. I am curious how performant the query is. Have you tried against your 10M records? How fast was it?
ASKER
Performance is awesome! We decided to go back even further in history. We have 24M rows and the query finished in 22 seconds. My cursor logic was running at @ 3 hours for a small sampling of data. THANK YOU AGAIN!
Thanks for the feedback.
Take it as a lesson to use "set based" operations in SQL whenever you can and use cursors only where they are absolutely the only option :)
Cheers, Paul
Take it as a lesson to use "set based" operations in SQL whenever you can and use cursors only where they are absolutely the only option :)
Cheers, Paul