Selecting ALL Max Values SQL query

Question

I am working with two tables in this query Table 1: admit , Table 2: Billing. What I want to do is show people who are admitted to our crisis services (program codes '44282' and '44283') . For these people, I want to show their insurance, which is under the field guarantor_id in the Billing Table. To do this, I need to show ALL the max coverage effective dates cov_effective_date where the coverage effective date is less than the admission date preadmit_admission_date and the coverage expiration date cov_expiration_date is greater than the admission date (or Is Null). The code I have right now does everything I want, but doesn't get all the max coverage effective dates. So if someone had two different insurances that began on the same date it will only show one and I want it show both.

Select 
 A.patid
,A.episode_number
,A.preadmit_admission_date
,A.program_code
,A.program_value
,A.c_date_of_birth
,A.guarantor_id
,max(A.cov_effective_date) as "MaxDate"

from(

Select
  SA.patid
 ,SA.episode_number
 ,SA.preadmit_admission_date
 ,SA.program_code
 ,SA.program_value
 ,SA.c_date_of_birth
 ,BGE.guarantor_id
 ,BGE.cov_effective_date

 From System.view_episode_summary_admit as "SA"

 Left Outer Join

 (Select 
   BG.patid
  ,BG.episode_number
  ,BG.guarantor_id
  ,BG.cov_effective_date
  ,BG.cov_expiration_date

  from System.billing_guar_emp_data as "BG"

  Inner Join

  (Select patid, episode_number, preadmit_admission_date
  from System.view_episode_summary_admit ) as "A"
  On
  (A.patid = BG.patid) and (A.episode_number = BG.episode_number)

  Where
  BG.cov_effective_date <= preadmit_admission_date and
 (BG.cov_expiration_date >= preadmit_admission_date or
  BG.cov_expiration_date  Is Null)
  ) as "BGE"
  on
 (BGE.patid = SA.patid) and (BGE.episode_number = SA.episode_number)

  Where
  (program_code = '44282' or program_code = '44283' )
   and preadmit_admission_date >= {?Start Date}
   and preadmit_admission_date <= {?End Date}
   ) A

   Group By Patid, Episode_number

Answer 1

Sorry this is such a psuedo answer.

Select (your fields)
from (your entire query)bg
left join
   (select patid, max(cov_effective_date) maxdate from  system.billing_guar_emp_data group by patid) maxdate
on maxdate.patid = bg.patidate

Remove the group bys for the aggregate...you can now refer to maxdate.maxdate as a field in your opening select statement. Might be a better place to join this maxdate than joined at the very end of the query (possibly right under BG in the from statement), but psuedo code right? :) Hopefully you can apply the concept, let me know I'm free (freer?) in the afternoon if you need more.