Edit: Solved with a lot of help from Dems, I will post a truncated version of the query which is now working very well!
SELECT
*
FROM
O_PERSONS
/*The below left join returns the most recently added ethnicity classification*/
LEFT JOIN
(SELECT
ROW_NUMBER() OVER (PARTITION BY O_CLASSIFICATIONS.CLA_SUBJECT_ID ORDER BY O_CLASSIFICATIONS.CLA_DATE_NOTIFIED DESC) AS Sequence_ID,
O_CLASSIFICATIONS.CLA_CAT_ID,
O_CLASSIFICATIONS.CLA_SUBJECT_ID
FROM
O_CLASSIFICATIONS
WHERE
O_CLASSIFICATIONS.CLA_SUBJECT_IND = 'P'
AND
O_CLASSIFICATIONS.CLA_TOP_CAT_ID = 'ETHNIC'
AND
O_CLASSIFICATIONS.CLA_CAT_ID <> 'DECLINED'
) ETHNIC
ON ETHNIC.CLA_SUBJECT_ID = O_PERSONS.PER_ID
AND ETHNIC.Sequence_ID = 1
/*The below left join returns the most recently added PCG classification*/
LEFT JOIN
(SELECT
ROW_NUMBER() OVER (PARTITION BY O_CLASSIFICATIONS.CLA_SUBJECT_ID ORDER BY O_CLASSIFICATIONS.CLA_DATE_NOTIFIED DESC) AS Sequence_ID,
O_CLASSIFICATIONS.CLA_CAT_ID,
O_CLASSIFICATIONS.CLA_SUBJECT_ID
FROM
O_CLASSIFICATIONS
WHERE
O_CLASSIFICATIONS.CLA_SUBJECT_IND = 'P'
AND
O_CLASSIFICATIONS.CLA_TOP_CAT_ID = 'PRIMARY'
AND
O_CLASSIFICATIONS.CLA_CAT_ID <> 'DECLINED'
) PCG
ON PCG.CLA_SUBJECT_ID = O_PERSONS.PER_ID
AND PCG.Sequence_ID = 1
WHERE
O_PERSONS.PER_ID LIKE 'P%'
I am currently trying to write a query which will return certain details for clients on our system. Whilst a client will only have one date of birth, gender, and P ID, they may have multiple ethnicities (as a result of data quality) and also client groups (this is more legitimate as a client’s needs may change). However, for these particular items, I am only interested in the most recently added ethnicities or client groups. Below I have written a query which assigns a row number to the ethnicity and to the client group with a plan to return only those which equal 1, as these generally will be the most recent. However, I have run into 2 issues, one of which I can resolve, the other of which I’m not so sure.
First off, some clients will not have an ethnicity or a client group recorded. When running the below query, they return with very odd row numbers (often in the thousands). However, I know in my ‘where’ that I could specify that a row is returned if client group or ethnicity was empty (as these will be data quality cases which need to be addressed).
The second issue is slightly trickier which I will try to represent with a table below. Please note I have abbreviated the table for ease of input and understanding.
P ID Ethnicity PCG RN E RN P
P1 WB OV 1 2
P1 WI OV 2 1
The above client had two ethnicities, though WB is the most recent (therefore the 1 in Row Number E is correct). However, the client has only had one PCG recorded but the row number returns a 2 in the first row (arguably the row I want to return). I’m not sure why though I guess because ETHNIC.CLA_SUBJECT_ID is joined on O_PERSONS.PER_ID and PER_ID occurs twice, that is why it thinks there is two rows for that particular field. However, even if that is the case, is there a way to force just 1’s to appear in one row? Or could I do this a completely different way? Hopefully this query makes some sense, apologies if parts are unclear. Thanks,
SELECT
O_PERSONS.PER_ID as "P ID",
olm_bo.get_per_name(O_PERSONS.PER_ID) as "Full Name",
O_PERSONS.PER_BIRTH_DATE as "Date of Birth",
case
when O_PERSONS.PER_DECEASED_DATE is null then FLOOR(MONTHS_BETWEEN(sysdate,O_PERSONS.PER_BIRTH_DATE)/12)
else FLOOR(MONTHS_BETWEEN(O_PERSONS.PER_DECEASED_DATE,O_PERSONS.PER_BIRTH_DATE)/12)
end as "Age",
O_PERSONS.PER_DECEASED_DATE as "Date Deceased",
olm_bo.get_gender_desc('P', O_PERSONS.PER_GENDER) as "Gender",
CASE
WHEN ETHNIC.CLA_CAT_ID IN ('C1','C2','C3','C4','ABAN','AIND','AOTH','APKN') THEN 'Asian or Asian British'
ELSE NULL
End as "Ethnicity - Top" ,
CASE
WHEN ETHNIC.CLA_CAT_ID IN ('BAFR','D2') THEN 'African'
ELSE NULL
End as "Ethnicity - Detail" ,
CASE
WHEN PCG.CLA_CAT_ID IN ('ASYLUM','REFUGEE') THEN 'Asylum Seeker/Refugee'
ELSE NULL
End as "PCG",
CASE
WHEN PCG.CLA_CAT_ID IN ('ASYLUM','REFUGEE') THEN 'Asylum Seeker/Refugee'
ELSE NULL
End as "PCG - Top",
CASE
WHEN PCG.CLA_CAT_ID IN ('ASYLUM','REFUGEE') THEN 'Asylum Seeker/Refugee'
ELSE NULL
End as "PCG - DETAIL",
to_char(row_number() over(PARTITION BY ETHNIC.CLA_SUBJECT_ID ORDER BY abs(sysdate - ETHNIC.CLA_DATE_NOTIFIED) asc)) as "Row Number E",
to_char(row_number() over(PARTITION BY PCG.CLA_SUBJECT_ID ORDER BY abs(sysdate - PCG.CLA_DATE_NOTIFIED) asc))as "Row Number P"
FROM
O_PERSONS
LEFT JOIN O_CLASSIFICATIONS ETHNIC ON ETHNIC.CLA_SUBJECT_ID = O_PERSONS.PER_ID
AND ETHNIC.CLA_SUBJECT_IND = 'P'
AND ETHNIC.CLA_TOP_CAT_ID = 'ETHNIC'
AND ETHNIC.CLA_CAT_ID <> 'DECLINED'
LEFT JOIN O_CLASSIFICATIONS PCG ON PCG.CLA_SUBJECT_ID = O_PERSONS.PER_ID
AND PCG.CLA_SUBJECT_IND = 'P'
AND PCG.CLA_TOP_CAT_ID = 'PRIMARY'
AND PCG.CLA_CAT_ID <> 'DECLINED'
WHERE
/*Following line excludes any clients whose is less than 18)*/
O_PERSONS.PER_BIRTH_DATE > trunc(add_months(O_PERSONS.PER_BIRTH_DATE,-216))
AND O_PERSONS.PER_ID LIKE 'P%'
You should apply
ROW_NUMBER()before you do the joins.