Find closest or higher values in SQL - sql

Question

I have a table:
table1
rank value
1 10
25 120
29 130
99 980
I have to generate the following table:
table2
rank value
1 10
2 10
3 10
4 10
5 10
6 10
7 10
8 10
9 10
10 10
11 10
12 10
13 120
14 120
15 120
.
.
.
.
25 120
26 120
27 130
28 130
29 130
30 130
.
.
.
.
.
62 980
63 980
.
.
.
99 980
100 980
So, table2 should have all values from 1 to 100. There are 3 cases:
If it's an exact match, for ex. rank 25, value would be 120
Find closest, for ex. for rank 9 in table2, we do NOT have exact match, but 1 is closest to 9 (9-1 = 8 whereas 25-9 = 16), so assign value of 1
If there is equal distribution from both sides, use higher rank value, for ex. for rank 27, we have 25 as well as 29 which are equally distant, so take higher value which is 29 and assign value.

Answer 1

something like
-- your testdata
with table1(rank,
value) as
(select 1, 10
from dual
union all
select 25, 120
from dual
union all
select 29, 130
from dual
union all
select 99, 980
from dual),
-- range 1..100
data(rank) as
(select level from dual connect by level <= 100)
select d.rank,
min(t.value) keep(dense_rank first order by abs(t.rank - d.rank) asc, t.rank desc)
from table1 t, data d
group by d.rank;

Answer 2

If I understand well your need, you could use the following:
select num, value
from (
select num, value, row_number() over (partition by num order by abs(num-rank) asc, rank desc) as rn
from table1
cross join ( select level as num from dual connect by level <= 100) numbers
)
where rn = 1
This joins your table with the [1,100] interval and then keeps only the first row for each number, ordering by the difference and keeping, in case of equal difference, the greatest value.

Answer 3

Join hierarchical number generator with your table and use lag() with ignore nulls clause:
select h.rank, case when value is null
then lag(value ignore nulls) over (order by h.rank)
else value
end value
from (select level rank from dual connect by level <= 100) h
left join t on h.rank = t.rank
order by h.rank
Test:
with t(rank, value) as (
select 1, 10 from dual union all
select 25, 120 from dual union all
select 29, 130 from dual union all
select 99, 980 from dual )
select h.rank, case when value is null
then lag(value ignore nulls) over (order by h.rank)
else value
end value
from (select level rank from dual connect by level <= 100) h
left join t on h.rank = t.rank
order by h.rank
RANK RANK
---------- ----------
1 10
2 10
...
24 10
25 120
26 120
27 120
28 120
29 130
30 130
...
98 130
99 980
100 980

Answer 4

Here's an alternative that doesn't need a cross join (but does use a couple of analytic functions, so you'd need to test whether this is more performant for your set of data than the other solutions):
WITH sample_data AS (SELECT 1 rnk, 10 VALUE FROM dual UNION ALL
SELECT 25 rnk, 120 VALUE FROM dual UNION ALL
SELECT 29 rnk, 130 VALUE FROM dual UNION ALL
SELECT 99 rnk, 980 VALUE FROM dual)
SELECT rnk + LEVEL - 1 rnk,
CASE WHEN rnk + LEVEL - 1 < rnk + (next_rank - rnk)/2 THEN
VALUE
ELSE next_value
END VALUE
FROM (SELECT rnk,
VALUE,
LEAD(rnk, 1, 100 + 1) OVER (ORDER BY rnk) next_rank,
LEAD(VALUE, 1, VALUE) OVER (ORDER BY rnk) next_value
FROM sample_data)
CONNECT BY PRIOR rnk = rnk
AND PRIOR sys_guid() IS NOT NULL
AND LEVEL <= next_rank - rnk;
RNK VALUE
---------- ----------
1 10
2 10
... ...
12 10
13 120
... ...
24 120
25 120
26 120
27 130
28 130
29 130
30 130
... ...
63 130
64 980
65 980
... ...
98 980
99 980
100 980
N.B, I'm not sure why you have 62 and 63 as having a value of 980 - the mid point between 29 and 99 is 64.
Also, you'll see that I've used 100 + 1 instead of 101 - this is because if you wanted to parameterise things, you would replace 100 with the parameter - e.g. v_max_rank + 1

Answer 5

You can use cross join. Use the below query to get your result:
select t1.* from table1 t1
cross join
(select * from table1) t2
on (t1.rank=t2.rank);