Laravel pivot table need to have duplicate entries - mysql

Question

I am using Laravel to build a small customer list system.
I need to link COMPANY with CONTACT_PERSON. In a normal situation, I can use many to many pivot tables to link and update them.
However, I need to keep historical records. That means the same person can act as a contact in the period earlier, resigned, and reappointed later with another period.
I try to duplicate the pivot table entries with phpMyAdmin, makes the same COMPANY linked the same CONTACT_PERSON twice, and two entries were found when retrieving the COMPANY records.
However, how can use Laravel duplicate the entries? How to use Laravel to CURD those. Or I just do it in the wrong way?
Thank you very much!
EDIT :
Example :
Company A employed Mr. A between 01-01-2001 till 02-02-2001,
Compnay A employed Mr. A again on 03-03-2001 till 04-04-2001.
There are company B,C,D ... in company table,
There are Mr. B, C , D in the employee table too.
Use Laravel relationship pivot table to link company A to Mr. A will have two records in the above case (I need to have a historical record).
Is it the right way to handle such cases with Laravel many to many relationships? Or I should consider other ways ?

Answer 1

A pivot table can contain additional columns. You could consider adding migrations that add a started_at and resigned_at datetime field to your pivot table.
Your data structure would look something like this:
Company
id
...
Contact_person_company
contact_person_id
company_id
started_at
resigned_at
Contact person
id
...
After that, you could create functions in your model to work with the pivot columns and check for their status. A null value for the resigned_at column indicates that the ContactPerson is still active.
<?php
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;
class Company extends Model
{
// ... other functions
public function contactPersons(): BelongsToMany
{
$this->belongsToMany(Company::class)
->withPivot('started_at', 'resigned_at')
->wherePivotNull('resigned_at');
}
public function resignedContactPersons()
{
$this->belongsToMany(Company::class)
->withPivot('started_at', 'resigned_at')
->wherePivotNotNull('resigned_at');
}
}
You should define these functions as well on the ContactPerson model.
If the logic gets very complicated, consider creating a Pivot model (CompanyContactPerson).
Please note that the combination of contact_person_id, company_id started_at should be unique. Otherwise, considering adding a primary key like ID the company_contact_person table to identify these records.