Oracle JSON_QUERY with path as query column value - oracle

Question

I try to get part of JSON column in each result row this select
SELECT TRIM(a.symbol),
TRIM(a.ex_name),
to_char(a.date_rw, 'dd-MON-yyyy'),
a.pwr,
a.last,
JSON_QUERY(b.mval, '$."-9"') as value
FROM adviser_log a
INNER JOIN profit_model_d b
ON a.date_rw = b.date_rw
WHERE a.date_rw = '08-OCT-2021'
select result:
VERY NAS 08-OCT-2021 -9 8.9443 {"sl":-3.6,"tp":5,"avg":1.368,"max":5,"min":-3.6,"count":1}
As a json path I put "-9" literal but I wanna put as path a.pwr is it possible
I tried put CONCAT('$.', a.pwr) without result
Is it any way to create dynamical json path into JSON_QUERy
I want to match part json which key compared with a.pwr to each row in select
Thx

Answer 1

You can use a function to dynamically get the JSON value:
WITH FUNCTION get_value(
value IN CLOB,
path IN VARCHAR2
) RETURN VARCHAR2
IS
BEGIN
RETURN JSON_OBJECT_T( value ).get_object( path ).to_string();
END;
SELECT TRIM(a.symbol) AS symbol,
TRIM(a.ex_name) AS ex_name,
to_char(a.date_rw, 'dd-MON-yyyy') AS date_rw,
a.pwr,
a.last,
get_value(b.mval, a.pwr) AS value
FROM adviser_log a
INNER JOIN profit_model_d b
ON a.date_rw = b.date_rw
WHERE a.date_rw = DATE '2021-10-08'
Which, for your sample data:
CREATE TABLE adviser_log (symbol, ex_name, date_rw, pwr, last) AS
SELECT 'VERY', 'NAS', DATE '2021-10-08', -9, 8.9443 FROM DUAL;
CREATE TABLE profit_model_d (date_rw DATE, mval CLOB CHECK (mval IS JSON));
INSERT INTO profit_model_d (
date_rw,
mval
) VALUES (
DATE '2021-10-08',
'{"-9":{"sl":-3.6,"tp":5,"avg":1.368,"max":5,"min":-3.6,"count":1}}'
);
Outputs:
SYMBOL
EX_NAME
DATE_RW
PWR
LAST
VALUE
VERY
NAS
08-OCT-2021
-9
8.9443
{"sl":-3.6,"tp":5,"avg":1.368,"max":5,"min":-3.6,"count":1}
db<>fiddle here