Oracle SQL- Flag records based on record's date vs history

Question

This is my 1st post on the forum. Usually I was able to find what I needed - but to tell the truth - I am not really sure how to ask a correct question to the issue. Therefore,

Answer 1

You can use LAG function:

SELECT
"REGION"
, "COUNTRY"
, "IDNum"
, "CUSTOMER"
, "BUSSINESS"
, "FISCALYEARMONTH"
, "FISCALYEAR"
, SUM("VALUE") 
, MAX(CASE WHEN to_date(prev_fym,'YYYYMM')  >= ADD_MONTHS (to_date("FISCALYEARMONTH",'YYYYMM'), -24) THEN 'Existing' 
           ELSE NULL END) "HISTORICAL_PURCHASE_FLAG"
FROM
(
    SELECT
    T1."REGION"
    , T1."COUNTRY"
    , T1."IDNum"
    , T1."CUSTOMER"
    , T1."BUSSINESS"
    , T3."FISCALYEARMONTH"
    , T3."FISCALYEAR"
    , T4."VALUE"
    , LAG ("FISCALYEARMONTH", 1) OVER (PARTITION BY T1."IDNum" ORDER BY T3."FISCALYEARMONTH" DESC) prev_fym 
    FROM
    "DATABASE"."SALES" T4
    , "DATABASE"."CUSTOMER" T1
    , "DATABASE"."PRODUCT" T2
    , "DATABASE"."TIME" T3
    WHERE
    T4."CUSTOMERID" = T1."CUSTOMERID"
    AND T4."PRODUCTID" = T2."PRODUCTID"
    AND T4."DATEID" = T3."DATEID"
    AND T1."COUNTRY" IN ('ENGLAND', 'France')
    AND T3."FISCALYEAR" IN ('2014','2015','2016')
)
WHERE "FISCALYEAR" IN ('2016')
GROUP BY
"REGION"
, "COUNTRY"
, "IDNum"
, "CUSTOMER"
, "BUSSINESS"
, "FISCALYEARMONTH"
, "FISCALYEAR"
;

Answer 2

Using a simplified "input" table... You can use the LAG() analytic function and a comparison condition to populate your last column. I assume your fiscalyearmonth is a number - if it is a character field, wrap fiscalyearmonth within TO_NUMBER(). (It would be much better if in fact you stored these as true Oracle dates, perhaps date 2016-06-01 instead of 201606, but I worked with what you have currently... and took advantage that in numeric format, "24 months ago" simply means "subtract 200").

with inputs (linenum, idnum, fiscalyearmonth) as (
       select 1, 255, 201605 from dual union all
       select 2, 123, 201602 from dual union all
       select 3, 255, 201601 from dual union all
       select 4, 255, 201210 from dual
     )
select linenum, idnum, fiscalyearmonth, 
       case when fiscalyearmonth 
                 - lag(fiscalyearmonth) 
                           over (partition by idnum order by fiscalyearmonth) < 200
            then 'Existing' else 'New' end         as flag
from   inputs
order by linenum;


   LINENUM      IDNUM FISCALYEARMONTH FLAG
---------- ---------- --------------- --------
         1        255          201605 Existing
         2        123          201602 New
         3        255          201601 New
         4        255          201210 New

Answer 3

You can achieve using row_number() function as below... modify as per your need...I assumed 2 years (means previous 24 months from sysdate ). You can run the sub-queries separately to check how its working.

Select 
"REGION"
,"COUNTRY"
,"IDNum"
,"CUSTOMER"
,"BUSSINESS"
,"FISCALYEARMONTH"
,"FISCALYEAR"
,"VALUE"
, ( case when ( TXNNO = 1 or TOTAL_TXN_LAST24MTH = 0 ) then 'New' else 'Existing' end ) as "HISTORICAL_PURCHASE_FLAG"  -- if no txn in last 24 month or its first txn then 'new' else 'existing'
from
(
  select 
  SubQry."REGION"
  , SubQry."COUNTRY"
  , SubQry."IDNum"
  , SubQry."CUSTOMER"
  , SubQry."BUSSINESS"
  , SubQry."FISCALYEARMONTH"
  , SUBQRY."FISCALYEAR"
  , SUBQRY."VALUE"
  , ROW_NUMBER() over (partition by SUBQRY."REGION",SUBQRY."COUNTRY",SUBQRY."IDNum",SUBQRY."CUSTOMER",SUBQRY."BUSSINESS" order by SUBQRY."FISCALYEARMONTH") as TXNNO,
  , SUM(case when (TO_NUMBER(TO_CHAR(sysdate,'YYYYMM')) - SUBQRY."FISCALYEARMONTH") < 24 then 1 else 0 end) as TOTAL_TXN_LAST24MTH
  From
  (
    SELECT
    T1."REGION"
    , T1."COUNTRY"
    , T1."IDNum"
    , T1."CUSTOMER"
    , T1."BUSSINESS"
    , T3."FISCALYEARMONTH"
    , T3."FISCALYEAR"
    , SUM(T4."VALUE") as VALUE
    FROM
    "DATABASE"."SALES" T4
    , "DATABASE"."CUSTOMER" T1
    , "DATABASE"."PRODUCT" T2
    , "DATABASE"."TIME" T3
    WHERE
    T4."CUSTOMERID" = T1."CUSTOMERID"
    AND T4."PRODUCTID" = T2."PRODUCTID"
    AND T4."DATEID" = T3."DATEID"
    AND T3."FISCALYEAR" IN ('2016')
    AND T1."COUNTRY" IN ('ENGLAND', 'France')
    GROUP BY
    T1."REGION"
    , T1."COUNTRY"
    , T1."IDNum"
    , T1."CUSTOMER"
    , T1."BUSSINESS"
    , T3."FISCALYEARMONTH"
    , T3."FISCALYEAR"
  ) SUBQRY
);

Answer 4

Another solution might be to outer Join "DATABASE"."SALES" T4 a second time as T5, wilter the fiscal year via WHERE to < t4.FiscalYear-2. If the Column is NULL, the record is new, if the outer join results in a value, the record is historic.