Postgres 13

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create table birthdates (bday_day int , bday_month int,  bday_year int);
insert into birthdates values(25,6,2021);
insert into birthdates values(30,6,null);
insert into birthdates values(29,7,2021);
insert into birthdates values(2,7,null);
insert into birthdates values(24,7,2000);
insert into birthdates values(4,8,null);
1 rows affected

1 rows affected

1 rows affected

1 rows affected

1 rows affected

1 rows affected

select *,
make_date(cast(extract(year from CURRENT_DATE)as int),bday_month,bday_day)birthdate
from birthdates
where (case cast(extract (month from current_date) as int) when 12 then
1 else cast(extract (month from current_date) as int)+1 end)=bday_month


bday_day
bday_month
bday_year
birthdate


29
7
2021
2021-07-29

2
7
null
2021-07-02

24
7
2000
2021-07-24


select *,
make_date(cast(extract(year from CURRENT_DATE)as int),bday_month,bday_day)birthdate
from birthdates
where make_date(cast(extract(year from CURRENT_DATE)as int),bday_month,bday_day)>current_date
and make_date(cast(extract(year from CURRENT_DATE)as int),bday_month,bday_day)<=current_date + INTERVAL '30 day';


bday_day
bday_month
bday_year
birthdate


25
6
2021
2021-06-25

30
6
null
2021-06-30

2
7
null
2021-07-02

24
7
2000
2021-07-24

bday_day	bday_month	bday_year	birthdate
25	6	2021	2021-06-25
30	6	null	2021-06-30
2	7	null	2021-07-02
24	7	2000	2021-07-24