How to compare two comma separated string and insert in DB - oracle

Question

I have following table (Users) with 2 columns and trying to update second column with first column ( first column is autoincrement and primary key field).
UserId CatId
1 10
2 78
3 99
4 89
5 80
I am finding difficult to update second column with P_uid order by (1,3,4). I tried normal Update statement but it doesn't work. I am passing following ids into SP.
P_uid varchar2(20) := '1,3,4';
P_new_cat_id varchar2(20) := '100,12,13';
Expected output
---------------
UserId CatId
1 100
2 78
3 12
4 13
5 80

Answer 1

Use a MERGE statement:
MERGE INTO users dst
USING (
SELECT 1 AS id, 100 AS new_catid FROM DUAL UNION ALL
SELECT 3, 12 FROM DUAL UNION ALL
SELECT 4, 13 FROM DUAL
) src
ON (src.id = dst.userid)
WHEN MATCHED THEN
UPDATE
SET catid = src.new_catid;
Which, for the sample data:
CREATE TABLE users (UserId, CatId) AS
SELECT 1, 10 FROM DUAL UNION ALL
SELECT 2, 78 FROM DUAL UNION ALL
SELECT 3, 99 FROM DUAL UNION ALL
SELECT 4, 89 FROM DUAL UNION ALL
SELECT 5, 80 FROM DUAL;
Then, after the merge, the table contains:
USERID
CATID
1
100
2
78
3
12
4
13
5
80
If you have delimited strings then (apart from finding a better solution for passing multi-row data) you can split the values into rows using a row-generator function and use the previous technique:
DECLARE
P_uid varchar2(20) := '1,3,4';
P_new_cat_id varchar2(20) := '100,12,13';
BEGIN
MERGE INTO users dst
USING (
SELECT REGEXP_SUBSTR(p_uid, '\d+', 1, LEVEL) AS id,
REGEXP_SUBSTR(p_new_cat_id, '\d+', 1, LEVEL) AS new_catid
FROM DUAL
CONNECT BY LEVEL <= LEAST(
REGEXP_COUNT(p_uid, '\d+'),
REGEXP_COUNT(p_new_cat_id, '\d+')
)
) src
ON (src.id = dst.userid)
WHEN MATCHED THEN
UPDATE
SET catid = src.new_catid;
END;
/
Which outputs the same.
db<>fiddle here