How to give a client's state by time - oracle

Question

Table t_customer_statistics
trx_date - transaction date
cuid - id person(divide prospect and client)
lifecycle_status - this column must be filled
I need to give status to a client based on his condition
acquired - this month was the very first transaction
existing - there was a transaction last month
reactivated - there was no transaction last month
sleeping - there has been no transaction for the last 90 days (there have been no subsequent ones since the last transaction, more than 90 days)
I roughly made a code like this
UPDATE t_customer_statistics
SET Lifecycle_status =
case
when to_char (trunc (trx_date, 'mm'), 'mm.yyyy') = to_char (trunc (sysdate, 'mm'), 'mm.yyyy') then 'acquired'
when to_char (trunc (trx_date, 'mm'), 'mm.yyyy') = to_char (trunc (sysdate, 'mm') - 1, 'mm.yyyy') then 'existing'
when to_char (trunc (trx_date, 'mm'), 'mm.yyyy') = to_char (trunc (sysdate, 'mm') - 40, 'mm.yyyy') then 'reactivated'
when to_char (trunc (trx_date, 'mm'), 'mm.yyyy') <to_char (trunc (sysdate, 'mm') - 90, 'mm.yyyy') then 'sleeping'
end
but when they gave me an example, if the client made the first transaction and then fell asleep, then he has two states in the end, and sleeping must be separated so that there is a separate
PS. must be considered by transaction from the first and last

Answer 1

You could use a MERGE statement like this:
MERGE INTO clients dst
USING (
SELECT rowid rid,
LEAD(dt, 1) OVER (PARTITION BY id ORDER BY dt DESC) AS prev_dt,
LAG(dt, 1) OVER (PARTITION BY id ORDER BY dt DESC) AS next_dt
FROM clients
) src
ON ( dst.ROWID = src.rid )
WHEN MATCHED THEN
UPDATE
SET status = CASE
WHEN prev_dt IS NULL
THEN 'acquired'
WHEN MONTHS_BETWEEN(TRUNC(dst.dt, 'MM'), TRUNC(src.prev_dt)) <= 1
THEN 'existing'
ELSE 'reactivated'
END
||
CASE
WHEN COALESCE(src.next_dt, SYSDATE) >= dst.dt + INTERVAL '90' DAY
THEN ', sleeping'
END;
Which, for the sample data:
CREATE TABLE clients (id, dt, status ) AS
SELECT 1, DATE '2020-01-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-02-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-03-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-05-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-09-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-10-01', CAST( NULL AS VARCHAR2(20) ) FROM DUAL UNION ALL
SELECT 1, DATE '2020-10-01' + INTERVAL '91' DAY, CAST( NULL AS VARCHAR2(20) ) FROM DUAL;
Then the result of the MERGE is:
ID
DT
STATUS
1
01-JAN-20
acquired
1
01-FEB-20
existing
1
01-MAR-20
existing
1
01-MAY-20
reactivated, sleeping
1
01-SEP-20
reactivated
1
01-OCT-20
existing, sleeping
1
31-DEC-20
reactivated, sleeping
db<>fiddle here