SQL中如何获取12个月的连续数据

Question

I want to get the data for patients who has taken service for 12 months continuously. In my data I've Patient_ID and service_date fields.

I tried the query below, but the results aren't correct.

select a.*, count(distinct b.svcdate) over(partition by a.patientid, a.svcdate) as events,
count(month(SVCDATE)) over (partition by patientid, SVCDATE) as month_count
from iv_lasix_hf_data_pull as a
left join iv_lasix_hf_data_pull as b
on a.patientid = b.patientid
and b.svcdate >= a.svcdate
and b.svcdate <= dateadd(month, 12, a.svcdate) and month_count = 12;

Thank you for your help!!

Answer 1

select a.*, ROW_NUMBER() OVER(ORDER BY month(svcdate) AS ROW_NUMBER, DATEDIFF(M, ROW_NUMBER() OVER(ORDER BY month(svcdate)), svcdate) AS Diff from iv_lasix_hf_data_pull as a left join iv_lasix_hf_data_pull as b on a.patientid = b.patientid and b.svcdate >= a.svcdate and b.svcdate <= dateadd(month, 12, a.svcdate) and month_count = 12;

The above query will give you the same number in Diff if the months are continuous. You can group by and count according to your needs.