how to update child table in mysql - mysql

Question

I have have here an example table.incident table
+-------------+----------------------+
| incident_id | incident_description |
+-------------+----------------------+
| 1 | Accident |
| 2 | Homicide |
| 3 | Theft |
+-------------+----------------------+
incident_detail table:
+--------------------+-------------+-------------+
| incident_detail_id | person_name | incident_id |
+--------------------+-------------+-------------+
| 1 | errol | 1 |
| 2 | neo | 1 |
| 3 | aj | 1 |
| 4 | mark | 2 |
| 5 | calma | 2 |
| 6 | allan | 2 |
| 7 | dave | 3 |
| 8 | paul | 3 |
+--------------------+-------------+-------------+
I am providing a grid view like view that would allow the user to remove and add items in the incident_detail table. My question is, how can i update the incident_detail table? i am ok with adding new items, but removal. I don't know. Should i empty the entire table and insert the new items that the user added. But the problem here is that the existing items that weren't removed will be deleted and inserted again.

Answer 1

If you don't care about the incident_detail_id column incrementing more than it needs to, you can simply delete and re-insert the records, regardless of whether you changed the details for an incident.
It makes for easier SQL code but it does mean on each edit your IDs will go up. Assuming you're auto-incrementing.
After adding detail to Homicide you'll end up with:
+--------------------+-------------+-------------+
| incident_detail_id | person_name | incident_id |
+--------------------+-------------+-------------+
| 1 | errol | 1 |
| 2 | neo | 1 |
| 3 | aj | 1 |
| 9 | mark | 2 |
| 10 | calma | 2 |
| 11 | allan | 2 |
| 12 | new | 2 |
| 7 | dave | 3 |
| 8 | paul | 3 |
+--------------------+-------------+-------------+
If you're happy with that:
DELETE FROM incident_detail WHERE incident_id = 2;
INSERT INTO incident_detail (person_name, incident_id)
VALUES
('mark', 2)
('calma', 2)
('allan', 2)
('new', 2);