MySQL 8.0

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CREATE TABLE results (id INT, food TEXT, memo TEXT);
INSERT INTO results VALUES
(   1   , 'Cucumbers'  ,   NULL   ),
(   2   , 'Dandelions' ,   NULL   ),
(   3   , 'Salmons'    ,   NULL   ),
(   3   , 'Cucumbers'  ,   NULL   ),
(   4   , 'Tomatoes'   ,   NULL   );
SELECT * FROM results;


id
food
memo


1
Cucumbers
null

2
Dandelions
null

3
Salmons
null

3
Cucumbers
null

4
Tomatoes
null


SET @id := 3;
SET @memo := "Mostly liked it, only 15% didn't eat.| Only 10% have eaten, rest of all didn't even try.";
WITH cte AS ( SELECT food, ROW_NUMBER() OVER () rn
              FROM results 
              WHERE @id = id )
UPDATE results, cte
SET results.memo = TRIM(SUBSTRING_INDEX(SUBSTRING_INDEX(@memo, '|', cte.rn), '|', -1))
WHERE results.food = cte.food
  AND results.id = @id
  AND cte.rn <= 1 + LENGTH(@memo) - LENGTH(REPLACE(@memo, '|', ''));
SELECT * FROM results;


id
food
memo


1
Cucumbers
null

2
Dandelions
null

3
Salmons
Mostly liked it, only 15% didn't eat.

3
Cucumbers
Only 10% have eaten, rest of all didn't even try.

4
Tomatoes
null

id	food	memo
1	Cucumbers	null
2	Dandelions	null
3	Salmons	null
3	Cucumbers	null
4	Tomatoes	null