Oracle: Generate rows for missing years within range (sysyear + 9) - sql

Question

I have an Oracle 18c table that has rows for certain years:
with data (year_, amount) as (
select 2024, 100 from dual union all
select 2025, 200 from dual union all
select 2025, 300 from dual union all
select 2026, 400 from dual union all
select 2027, 500 from dual union all
select 2028, 600 from dual union all
select 2028, 700 from dual union all
select 2028, 800 from dual union all
select 2029, 900 from dual union all
select 2031, 100 from dual
)
select
*
from
data
YEAR_ AMOUNT
---------- ----------
2024 100
2025 200
2025 300
2026 400
2027 500
2028 600
2028 700
2028 800
2029 900
2031 100
I want at least one row for each year within this range: sysyear + 9. In other words, I want rows for 10 years, starting with the current year (currently 2023).
I'm missing rows for certain years: 2023, 2030, and 2032. So I want to generate filler rows for those missing years. The amount for the filler rows would be null.
It would look like this:
YEAR_ AMOUNT
---------- ----------
2023 --filler
2024 100
2025 200
2025 300
2026 400
2027 500
2028 600
2028 700
2028 800
2029 900
2030 --filler
2031 100
2032 --filler
In an Oracle SQL query, how can I select the rows and generate filler rows within the 10 year range?
Edit: I would prefer not to manually create a list of years in the query or in a table. I would rather create a dynamic range within the query.

Answer 1

Try it like here:
Select y.YEAR_, t.AMOUNT
From (Select EXTRACT(YEAR From SYSDATE) + LEVEL - 1 "YEAR_" From Dual Connect By LEVEL <= 10) y
Left Join tbl t ON(t.YEAR_ = y.YEAR_)
Order By y.YEAR_, t.AMOUNT
With your sample data:
WITH
tbl (YEAR_, AMOUNT) AS
(
Select 2024, 100 From Dual Union All
Select 2025, 200 From Dual Union All
Select 2025, 300 From Dual Union All
Select 2026, 400 From Dual Union All
Select 2027, 500 From Dual Union All
Select 2028, 600 From Dual Union All
Select 2028, 700 From Dual Union All
Select 2028, 800 From Dual Union All
Select 2029, 900 From Dual Union All
Select 2031, 100 From Dual
)
... the result is:
YEAR_
AMOUNT
2023
2024
100
2025
200
2025
300
2026
400
2027
500
2028
600
2028
700
2028
800
2029
900
2030
2031
100
2032

Answer 2

I broke out the CTE into multiple bits to help explain, but this should do the trick
SQL> with data (year_, amount) as (
2 select 2024, 100 from dual union all
3 select 2025, 200 from dual union all
4 select 2025, 300 from dual union all
5 select 2026, 400 from dual union all
6 select 2027, 500 from dual union all
7 select 2028, 600 from dual union all
8 select 2028, 700 from dual union all
9 select 2028, 800 from dual union all
10 select 2029, 900 from dual union all
11 select 2031, 100 from dual
12 ),
13 boundaries as (
14 select max(year_) maxy, min(year_) miny
15 from data
16 ),
17 all_the_years as
18 ( select miny+rownum-1 yr
19 from boundaries
20 connect by level <= maxy-miny+1
21 )
22 select *
23 from all_the_years a
24 left outer join data d
25 on ( a.yr = d.year_ )
26 order by 1;
YR YEAR_ AMOUNT
---------- ---------- ----------
2024 2024 100
2025 2025 200
2025 2025 300
2026 2026 400
2027 2027 500
2028 2028 700
2028 2028 800
2028 2028 600
2029 2029 900
2030
2031 2031 100
11 rows selected.
If its fixed at 10 years, then you don't need the MAX - just connect level <= 10