How can I update every fields data when remove rows - sql

Question

I'm looking for an way to update some rows right after I deleted some rows on MariaDB.
For examples, my talbes are look like:
--------------------------------------
| main_id | name | value | sub_id |
--------------------------------------
| 1 | DRINKS | 1000 | COKE |
| 1 | DRINKS | 2000 | BEER |
| 1 | DRINKS | 0600 | WATER |
| 2 | SALAD | 2000 | Peanut |
| 3 | BREADS | 1500 | FLAT |
| 3 | BREADS | 1000 | TOAST |
| 4 | BEEF | 3000 | SAUSAGE|
...
When I remove '2' SALAD, I want to update every rows main_id to main_id-1 like
--------------------------------------
| main_id | name | value | sub_id |
--------------------------------------
| 1 | DRINKS | 1000 | COKE |
| 1 | DRINKS | 2000 | BEER |
| 1 | DRINKS | 0600 | WATER |
| 2 | BREADS | 1500 | FLAT |
| 2 | BREADS | 1000 | TOAST |
| 3 | BEEF | 3000 | SAUSAGE|
...
// | 2 | SALAD | 2000 | Peanut | has removed so every main_id updated.
I cannot use PRIMARY KEY, because the things are so many duplicated.
If I have to join every rows, then I'm worried about performance, so I cannot find the way to solve the problem.
Thanks for your help.

Answer 1

After the Delete statement :
DELETE FROM t WHERE main_id = 2;
an Update statement containing Analytic Functions might be issued provided your DB version is 10.2+ :
UPDATE t
JOIN (WITH t2 AS
(
SELECT LAG(main_id,1) OVER (ORDER BY main_id) AS lg, t.*
FROM t
)
SELECT t2.*,
1 + SUM(CASE WHEN COALESCE(lg,main_id) = main_id THEN 0 ELSE 1 END )
OVER (ORDER BY main_id) AS new_id
FROM t2 ) t2
ON t.main_id = t2.main_id
SET t.main_id = t2.new_id;
to get main_id - 1 is updated for main_id column for main_id >2 for this individual case.
A Delete Trigger containing an Update cannot be applied on the same because of mutating trigger problem.
Demo