MySQL 8.0

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CREATE TABLE program (ProgramID  INT, WorkoutID TEXT);
INSERT INTO program VALUES
(1, '100,12,4,55,120,212,45'),
(2, '4,15,558,58,55,444,44');
SELECT * FROM program;

Records: 2  Duplicates: 0  Warnings: 0

ProgramID
WorkoutID

1
100,12,4,55,120,212,45

2
4,15,558,58,55,444,44

SELECT TRIM(BOTH ',' FROM REPLACE(CONCAT(',', WorkoutID, ','),',12,',','))
FROM program;

TRIM(BOTH ',' FROM REPLACE(CONCAT(',', WorkoutID, ','),',12,',','))

100,4,55,120,212,45

4,15,558,58,55,444,44

SELECT TRIM(BOTH ',' FROM REPLACE(CONCAT(',', WorkoutID, ','),',4,',','))
FROM program;

TRIM(BOTH ',' FROM REPLACE(CONCAT(',', WorkoutID, ','),',4,',','))

100,12,55,120,212,45

15,558,58,55,444,44