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Complicated SQL question

Posted on 2014-12-25
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Last Modified: 2014-12-29
Hi Experts,
I have a table containing the following:

ID
PatientID
EffectiveFrom (DateTime) Start of service
EffectiveTo (DateTime) End of service

Now I need to get the total count of patients serviced between a given date range, however (here goes the catch..) if a patient has 30 days or more between the one end of service (EffectiveTo) and the next start of service (EffectiveFrom) it should be counted as 2.

My question is, is there a way to get this count from a query/sql view or there is a need to create a custom function to loop for all records etc..?
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Question by:bfuchs
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19 Comments
 
LVL 51

Expert Comment

by:HainKurt
ID: 40517926
post a sample data & what you need from this sample

everything is possible :)
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LVL 45

Expert Comment

by:Kdo
ID: 40517928
Hi bfuchs,

Are you looking for the number of visits or the number of unique patients?  That is, if a patient visits multiple times during that date range, is he counted once or multiple times?
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LVL 51

Expert Comment

by:HainKurt
ID: 40517939
save this as a query, say q_Patient_ex

select PatientID, EffectiveFrom, EffectiveTo, 
       (select min(EffectiveFrom) from patients as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) next_service
  from patients as P1 

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test it by opening the query, or running this

select * from q_Patient_ex

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now run this

select sum(iff(datediff(d, EffectiveTo, nz(next_service, EffectiveTo))>30, 2, 1))
  from q_Patinets_X
 where @somedate between EffectiveFrom and EffectiveTo
 group by patientID

Open in new window

0
 
LVL 3

Author Comment

by:bfuchs
ID: 40517941
Hi,

@HainKurt,
Attached sample data, The number of patients I'm expecting to get for year 2004 is 3, as patientID 100 should be counted twice since there were more then 30 days between end od 2nd service and beginning of 3rd.

@Kdo,
Lets put it this way, I need the number of visits allowances (service date ranges), however if there are less then 30 days from when a patients service date ended and started again then its counted as one.

Thanks,
Ben
Book1.xls
0
 
LVL 51

Expert Comment

by:HainKurt
ID: 40517944
what is this giving?

select sum(iff(datediff(d, EffectiveTo, nz(next_service, EffectiveTo))>30, 2, 1)) as Patient_Count
  from (
select PatientID, EffectiveFrom, EffectiveTo, 
       (select min(EffectiveFrom) from patients as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) next_service
  from patients as P1 
) as q_Patinets_X
 where @somedate between EffectiveFrom and EffectiveTo

Open in new window


(combined my solution into one big chunk)
0
 
LVL 45

Expert Comment

by:Kdo
ID: 40517948
That really needs to be recursive SQL.  It could be that the visits chain to a length of 1 or many.  When 3 or more visits chain, care must be taken that only the first visit is counted.  Recursive SQL does that quite easily, but Access doesn't support it.
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LVL 3

Author Comment

by:bfuchs
ID: 40517954
@HainKurt,
See attached, (just replaced name of table to sheet1 as the one you gave exists).

@Kdo,
How about if I upload my data into a sql table would that help?
Untitled.png
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LVL 51

Expert Comment

by:HainKurt
ID: 40517975
ok, here it is:

select count(1) as PatientCount from (
select distinct PatientID, MoreThan30 from (
select PatientID, iif(datediff('d', EffectiveTo, nz(next_service,EffectiveTo))>30, 1, 0) as MoreThan30 from (
       select PatientID, EffectiveFrom, EffectiveTo,  
              (select min(EffectiveFrom) from patients as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) as next_service
         from patients as P1
) as x
) as y
) as z

Open in new window

0
 
LVL 51

Expert Comment

by:HainKurt
ID: 40517976
add a conditionbefore line 6 as

where @somedate between EffectiveFrom and EffectiveTo
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LVL 3

Author Comment

by:bfuchs
ID: 40517977
@HainKurt,
Actually I fixed your version re the syntax as follows
SELECT Sum(IIf(DateDiff("d",[EffectiveTo],nz([next_service],[EffectiveTo]))>30,2,1)) AS Patient_Count
FROM (select PatientID, EffectiveFrom, EffectiveTo, 
       (select min(EffectiveFrom) from sheet1 as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) as  next_service
  from sheet1 as P1 
) AS q_Patinets_X

Open in new window

However the results is 5, (while the table attached only has 4 records..and expected results is 3)
Thanks,
Ben
0
 
LVL 51

Expert Comment

by:HainKurt
ID: 40517980
or maybe this is better :) previous one has one more redundant select

select count(1) from (
select distinct PatientID,  iif(datediff('d', EffectiveTo, nz(next_service,EffectiveTo))>30, 1, 0) as MoreThan30 from (
       select PatientID, EffectiveFrom, EffectiveTo,  
              (select min(EffectiveFrom) from patients as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) as next_service
         from patients as P1
) as x
) as y

Open in new window

0
 
LVL 3

Author Comment

by:bfuchs
ID: 40517983
Ok your latest seems to work,
where do I add a date range to filter for, for example from 1/1/14 till 12/31/14?
0
 
LVL 51

Expert Comment

by:HainKurt
ID: 40517986
explanation:

line 3-5: I find result like

PatientID      EffectiveFrom      EffectiveTo      next_service
100      01/01/2014      01/02/2014      15/02/2014
100      15/02/2014      28/02/2014      01/04/2014
100      01/04/2014      02/04/2014      05/05/2014
200      01/01/2014      15/01/2014      
100      05/05/2014      15/05/2014      

line 2-6: here I find data like

PatientID      MoreThan30
100      0
100      1
200      0

line 1-7: here i get result
3
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LVL 51

Accepted Solution

by:
HainKurt earned 500 total points
ID: 40517988
after "from patients as P1"

select count(1) as PatientCount from (
select distinct PatientID,  iif(datediff('d', EffectiveTo, nz(next_service,EffectiveTo))>30, 1, 0) as MoreThan30 from (
       select PatientID, EffectiveFrom, EffectiveTo,  
              (select min(EffectiveFrom) from patients as P2 where P2.PatientID=P1.PatientID and P2.EffectiveFrom > P1.EffectiveTo) as next_service
         from patients as P1
      where [date] between EffectiveFrom and EffectiveTo
) as x
) as y

Open in new window

0
 
LVL 3

Author Comment

by:bfuchs
ID: 40517998
Hi HainKurt,
It looks like working well, just waiting to get hold of production data in order to finalize..
(I can see from your icon pic how you're already smiling from this big achievement -:)
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LVL 51

Expert Comment

by:HainKurt
ID: 40518000
i do like challenges :)
0
 
LVL 3

Author Closing Comment

by:bfuchs
ID: 40518009
Thanks HainKurt,
Great job, As said you like challenges, I will get more for you in the future:)
0
 
LVL 3

Author Comment

by:bfuchs
ID: 40518100
Hi HainKurt,
I need some modification on this query, posted another question, if you have a chance, please take a look at the following,
http://www.experts-exchange.com/Database/MS_Access/Q_28586854.html
Thanks
0
 
LVL 3

Author Comment

by:bfuchs
ID: 40521008
Hi HainKurt,

I am attaching a file with some data, according to the 30 days rule this should only return one record for year 2013, however your query its returning 2. (tested by running the middle part of your query), please let me know how to correct this.

Thanks,
Ben
Book1.xls
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