Current status based on week number ORACLE - sql

Question

I got this query on order to get all the days from the first day of the year (01/01/2018) to the end of next year (31/12/2019).
SELECT MYDATE,
TO_CHAR(NR_OF_SUNDAYS + 1,'FM09') WEEK_NUM,
FROM
(
SELECT MYDATE,
( (TRUNC(MYDATE,'DAY') - TRUNC(TRUNC(MYDATE,'YYYY'),'DAY')) / 7 ) +
CASE WHEN TO_CHAR(TRUNC(MYDATE,'YYYY'),'DAY') = 'SUN' THEN 1 ELSE 0 END AS NR_OF_SUNDAYS
FROM
( SELECT TRUNC (SYSDATE, 'YY') - 1 + LEVEL AS MYDATE
FROM DUAL
CONNECT BY LEVEL <= TRUNC (ADD_MONTHS (SYSDATE, 24), 'YY') -
TRUNC (SYSDATE, 'YY')
)
)
I need a column that specifies the following cases:
1) CASE WHEN MYDATE < TO_CHAR(SYSDATE, 'DD/MM/YYYY') THEN 'PAST DUE'
(this works its easy and no problem)
2) if my current =< mydate
week_num then 'CURRENT WEEK'(Excluding PAST DUE)
3) if my current week + one week then
'NEXT WEEK' (Excluding PAST DUE)
4) else FUTURE
Thanks a lot for your help.

Answer 1

So, in my answer I tried retain the logic behind your week number calculation.
However keep in mind that you could calculate week number using oracle to_char(date,'WW'), to_char(date,'IW'), to_char(date,'W') functions and then your life would be easier.
WW Week of year (1-53) where week 1 starts on the first day of the year and continues to the seventh day of the year.
W Week of month (1-5) where week 1 starts on the first day of the month and ends on the seventh.
IW Week of year (1-52 or 1-53) based on the ISO standard.
Having said all that here is my solution that uses only sql (note that defining and using a function would be a lot easier), based on your calculation method.
with date_table as (
SELECT MYDATE, to_number(TO_CHAR(NR_OF_SUNDAYS + 1,'FM09')) WEEK_NUM, to_number(to_char(MYDATE+1,'IW')) as nu
FROM
(
SELECT MYDATE,
( (TRUNC(MYDATE,'DAY') - TRUNC(TRUNC(MYDATE,'YYYY'),'DAY')) / 7 ) +
CASE WHEN TO_CHAR(TRUNC(MYDATE,'YYYY'),'DY', 'NLS_DATE_LANGUAGE = american') = 'SUN' THEN 1 ELSE 0 END AS NR_OF_SUNDAYS
FROM
( SELECT TRUNC (SYSDATE, 'YY') - 1 + LEVEL AS MYDATE
FROM DUAL
CONNECT BY LEVEL <= TRUNC (ADD_MONTHS (SYSDATE, 24), 'YY') -TRUNC (SYSDATE,'YY')
)
)
),
todays_week as
(
select distinct WEEK_NUM from date_table
where trunc(sysdate)=trunc(mydate)
),
pre_final as (
select MYDATE,WEEK_NUM, (select WEEK_NUM from todays_week) as todaysweek from date_table)
select MYDATE,sysdate,WEEK_NUM,todaysweek,
case when trunc(MYDATE) < trunc(sysdate) then 'PAST DUE'
when todaysweek = WEEK_NUM and abs(MYDATE-sysdate)<=7 then 'CURRENT WEEK'
when todaysweek +1 = WEEK_NUM and abs(MYDATE-sysdate)<=14 then 'Next Week'
else 'Future' end as description
from pre_final;
The main idea is to find today's week number and then use case when.
Here is my fiddle link with the results.
http://sqlfiddle.com/#!4/3149e4/148
EDIT 1:
Now, similar results one could achive with something like this:
select res.*,
case when trunc(MYDATE) < trunc(sysdate) then 'PAST DUE'
when todaysweek = WEEK_NUM and abs(MYDATE-sysdate)<=7 then 'CURRENT WEEK'
when todaysweek +1 = WEEK_NUM and abs(MYDATE-sysdate)<=14 then 'Next Week'
else 'Future' end as description
from (
SELECT MYDATE, to_number(to_char(MYDATE,'IW')) as WEEK_NUM,to_number(to_char(sysdate,'IW')) as todaysweek
FROM
( SELECT TRUNC (SYSDATE, 'YY') - 1 + LEVEL AS MYDATE
FROM DUAL
CONNECT BY LEVEL <= TRUNC (ADD_MONTHS (SYSDATE, 24), 'YY') -TRUNC (SYSDATE,'YY')
)) res