Update based on the comma seperated value - sql

Question

I have the below Table with two columns both columns are VARCHAR2(100).
PARAM_NAME PARAM_VALUE
PlanName,DemandMonth EUMOCP,01-2022
PlanName,DemandMonth EUMOCP,02-2022
PlanName,DemandMonth EUMOCP,03-2022
PlanName,DemandMonth EUMOCP,04-2021
How can we write a update on the table so that it only updates the corresponding value.
For example:
Update DemandMonth from 01-2022 to 04-2022.
Provided it only updates the columns based on the first column
For instance,
Column A Column B
1,2 3,4
based on 1 we can update 3 as it is before ',' similarly based on 2 we can update 4.
What we want to achieve is the first it identifies where is 'DemandMonth' and then accordingly update the second column. Also if possible can we write it for 4 or 5 comma seperated values?

Answer 1

Don't store values in delimited strings.
Change your table so the values are:
CREATE TABLE params ( id, param_name, param_value ) AS
SELECT 1, 'PlanName', 'EUMOCP' FROM DUAL UNION ALL
SELECT 1, 'DemandMonth', '01-2022' FROM DUAL UNION ALL
SELECT 2, 'PlanName', 'EUMOCP' FROM DUAL UNION ALL
SELECT 2, 'DemandMonth', '02-2022' FROM DUAL UNION ALL
SELECT 3, 'PlanName', 'EUMOCP' FROM DUAL UNION ALL
SELECT 3, 'DemandMonth', '03-2022' FROM DUAL UNION ALL
SELECT 4, 'PlanName', 'EUMOCP' FROM DUAL UNION ALL
SELECT 4, 'DemandMonth', '04-2021' FROM DUAL;
Then all you need to do to update the value is:
UPDATE params
SET param_value = '04-2022'
WHERE param_name = 'DemandMonth'
AND param_value = '01-2022';
There is no worrying about where in the delimited string the value is and it is all simple.

Answer 2

You should not do this and should refactor your table to not use delimited strings... however, you can use:
MERGE INTO params dst
USING (
WITH items ( rid, param_names, param_values, name, value, lvl, max_lvl ) AS (
SELECT ROWID,
param_name,
param_value,
REGEXP_SUBSTR( param_name, '[^,]+', 1, 1 ),
REGEXP_SUBSTR( param_value, '[^,]+', 1, 1 ),
1,
REGEXP_COUNT( param_value, '[^,]+' )
FROM params
UNION ALL
SELECT rid,
param_names,
param_values,
REGEXP_SUBSTR( param_names, '[^,]+', 1, lvl + 1 ),
REGEXP_SUBSTR( param_values, '[^,]+', 1, lvl + 1 ),
lvl + 1,
max_lvl
FROM items
WHERE lvl < max_lvl
)
SELECT rid,
LISTAGG(
CASE
WHEN name = 'DemandMonth' AND value = '01-2022'
THEN '04-2022'
ELSE value
END,
','
) WITHIN GROUP ( ORDER BY lvl ) AS param_value
FROM items
GROUP BY rid
HAVING COUNT(
CASE
WHEN name = 'DemandMonth' AND value = '01-2022'
THEN 1
END
) > 0
) src
ON ( dst.ROWID = src.rid )
WHEN MATCHED THEN
UPDATE SET param_value = src.param_value;
Which, for the sample data:
CREATE TABLE params ( param_name, param_value ) AS
SELECT 'PlanName,DemandMonth', 'EUMOCP,01-2022' FROM DUAL UNION ALL
SELECT 'PlanName,DemandMonth', 'EUMOCP,02-2022' FROM DUAL UNION ALL
SELECT 'PlanName,DemandMonth', 'EUMOCP,03-2022' FROM DUAL UNION ALL
SELECT 'PlanName,DemandMonth', 'EUMOCP,04-2021' FROM DUAL;
Then:
SELECT * FROM params;
Outputs:
PARAM_NAME
PARAM_VALUE
PlanName,DemandMonth
EUMOCP,04-2022
PlanName,DemandMonth
EUMOCP,02-2022
PlanName,DemandMonth
EUMOCP,03-2022
PlanName,DemandMonth
EUMOCP,04-2021
db<>fiddle here