要在mysql update Query中附加逗号分隔值，请不要重复

Question

I am storing table data as comma separated values like this

id    name       fk_id

1      abc       2,4,6
2       def      2,7,8

Now, I want to use CASE WHEN or some function in Update Query of MySQL which updates the field if no duplicate value:

For example, same value for fk_id then ignores else update like if 10 for id 1 then update but if 7 for id 2 then ignore

id    name       fk_id

1      abc       2,4,6,10
2       def      2,7,8

I tried the following code:

if(
            find_in_set($fk_id,fk_id),
            fk_id, 
            CONCAT_WS(',', fk_id, $fk_id)
          )

But not working.

Answer 1

Just update your code like as

set fk_id = if(find_in_set($fk_id,fk_id),
            fk_id, 
            CONCAT(fk_id, ',', $fk_id)
          )

Answer 2

Try this :

$sql = "
UPDATE `test` 
SET `fk_id` = CONCAT(fk_id, ',','" . $fk_id . "') 
WHERE `fk_id` REGEXP ',?(" . $fk_id . "),?'
";

NOTE : REGEXP is not the best option when it comes to speed.