SQL Server Get all Birthday Years - sql

Question

I have a table in SQL Server that is Composed of
ID, B_Day
1, 1977-02-20
2, 2001-03-10
...
I want to add rows to this table for each year of a birthday, up to the current birthday year.
i.e:
ID, B_Day
1,1977-02-20
1,1978-02-20
1,1979-02-20
...
1,2020-02-20
2, 2001-03-10
2, 2002-03-10
...
2, 2019-03-10
I'm struggling to determine what the best strategy for accomplishing this. I thought about recursively self-joining, but that creates far too many layers. Any suggestions?

Answer 1

The following should work
with row_gen
as (select top 200 row_number() over(order by name)-1 as rnk
from master..spt_values
)
select a.id,a.b_day,dateadd(year,rnk,b_day) incr_b_day
from dbo.t a
join row_gen b
on dateadd(year,b.rnk,a.b_day)<=getdate()
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=0d06c95e1914ca45ca192d0d192bd2e0

Answer 2

You can use recursive approach :
with cte as (
select t.id, t.b_day, convert(date, getdate()) as mx_dt
from table t
union all
select c.id, dateadd(year, 1, c.b_day), c.mx_dt
from cte c
where dateadd(year, 1, c.b_day) < c.mx_dt
)
select c.id, c.b_day
from cte c
order by c.id, c.b_day;
Default recursion is 100, you can add query hint for more recursion option (maxrecursion 0).

Answer 3

If your dataset is not too big, one option is to use a recursive query:
with cte as (
select id, b_day bday0, b_day, 1 lvl from mytable
union all
select
id,
bday0,
dateadd(year, lvl, bday0), lvl + 1
from cte
where dateadd(year, lvl, bday0) <= getdate()
)
select id, b_day from cte order by id, b_day
Demo on DB Fiddle:
id | b_day
-: | :---------
1 | 1977-02-20
1 | 1978-02-20
1 | 1979-02-20
1 | 1980-02-20
1 | 1981-02-20
1 | 1982-02-20
1 | 1983-02-20
1 | 1984-02-20
1 | 1985-02-20
1 | 1986-02-20
1 | 1987-02-20
1 | 1988-02-20
1 | 1989-02-20
1 | 1990-02-20
1 | 1991-02-20
1 | 1992-02-20
1 | 1993-02-20
1 | 1994-02-20
1 | 1995-02-20
1 | 1996-02-20
1 | 1997-02-20
1 | 1998-02-20
1 | 1999-02-20
1 | 2000-02-20
1 | 2001-02-20
1 | 2002-02-20
1 | 2003-02-20
1 | 2004-02-20
1 | 2005-02-20
1 | 2006-02-20
1 | 2007-02-20
1 | 2008-02-20
1 | 2009-02-20
1 | 2010-02-20
1 | 2011-02-20
1 | 2012-02-20
1 | 2013-02-20
1 | 2014-02-20
1 | 2015-02-20
1 | 2016-02-20
1 | 2017-02-20
1 | 2018-02-20
1 | 2019-02-20
1 | 2020-02-20
2 | 2001-03-01
2 | 2002-03-01
2 | 2003-03-01
2 | 2004-03-01
2 | 2005-03-01
2 | 2006-03-01
2 | 2007-03-01
2 | 2008-03-01
2 | 2009-03-01
2 | 2010-03-01
2 | 2011-03-01
2 | 2012-03-01
2 | 2013-03-01
2 | 2014-03-01
2 | 2015-03-01
2 | 2016-03-01
2 | 2017-03-01
2 | 2018-03-01
2 | 2019-03-01
2 | 2020-03-01