Oracle 12c Analytic Function - sql

Question

Is there a way to obtain the corresponding value X for a minimum value Y in a given dataset, in the same record, using Oracle Analytic functions, and without using a subquery?
For example:
If I have the following dataset "ds1":
Col1 Col2
A 1
B 2
C 3
D 4
E 4
A 10
Normally, in order to find the value "A" in Col1, which corresponds to the minimum value "1" in Col2, I would write the following query:
select ds1.col1
from ds1
, (select min (col2) col2
from ds1) min_ds1
where ds1.col2 = min_ds1.col2
/
Here is the executed code for such a Test Case:
### 1014.010, Start time is: 10/30/2019 11:39:35am
MYUN#MYDB-C1>>create table ds1 (col1 varchar2 (1), col2 number)
2 /
Table created.
Elapsed: 00:00:00.01
MYUN#MYDB-C1>>insert into ds1 (col1, col2)
2 select 'A', 1 from dual
3 union all select 'B', 2 from dual
4 union all select 'C', 3 from dual
5 union all select 'D', 4 from dual
6 union all select 'E', 4 from dual
7 union all select 'A', 10 from dual
8 /
6 rows created.
Elapsed: 00:00:00.02
MYUN#MYDB-C1>>commit
2 /
Commit complete.
Elapsed: 00:00:00.01
MYUN#MYDB-C1>>col col1 format a10
MYUN#MYDB-C1>>select ds1.col1
2 from ds1
3 , (select min (col2) col2
4 from ds1) min_ds1
5 where ds1.col2 = min_ds1.col2
6 /
COL1
----------
A
1 row selected.
Elapsed: 00:00:00.01
MYUN#MYDB-C1>>drop table ds1
2 /
Table dropped.
Elapsed: 00:00:00.03
The time now: 10/30/2019 11:39:36am
My question is:
Is it possible to derive the value "A" using an Analytic Function and without requiring a subquery? I am aware I can use the analytic function "ROW_NUMBER", sort the result in the ORDER BY clause, all in a subquery and then add a WHERE clause on the outer query where I say something like "WHERE RN = 1", where "RN" is the alias for the column in the subquery where the ROW_NUMBER function is used.

Answer 1

Use an aggregation function with KEEP to get the minimum values for another column:
Oracle Setup:
create table ds1 ( col1, col2 ) AS
select 'A', 1 from dual
union all select 'B', 2 from dual
union all select 'C', 3 from dual
union all select 'D', 4 from dual
union all select 'E', 4 from dual
union all select 'F', 10 from dual;
Aggregation Query:
SELECT MIN( col1 ) KEEP ( DENSE_RANK FIRST ORDER BY col2 ) AS col1
FROM ds1
Output:
| COL1 |
| :--- |
| A |
Analytic Query:
If you particularly want an analytic function then:
SELECT col1, col2
FROM (
SELECT ds1.*,
DENSE_RANK() OVER ( ORDER BY col2 ASC ) AS rnk
FROM ds1
)
WHERE rnk = 1
This has a sub-query but there is only a single table-scan.
You can easily integrate it into a huge query:
WITH my_huge_query AS (
<paste your huge query here>
)
SELECT *
FROM (
SELECT m.*,
DENSE_RANK() OVER( ORDER BY col2 ASC ) AS rnk
FROM my_huge_query m
)
WHERE rnk = 1
Output:
COL1 | COL2
:--- | ---:
A | 1
db<>fiddle here