(Mysql) how do i update parent and its reference in backend?

take a look at this table first then i'll explain.

parent {
id:number;
name:string;
}

child {
id:number;
name:string;
parent_id:number; //foreignKey to parent table
}

and this is the API request to do an update to backend

Request = {
    id:1; //parent id
    name:'update the name';
    childs:[
            {
             id:1,
             name:'child 1'
            },
            {
             id:null, //if null its mean i have to create this child
             name:'child 2'
            }
        ]
    }

so if the Request.childs have id on each item then i have to update the child, but if its doesn't have an id i have to create a new child.

And if child doesn't exist in Request.childs i have to delete it.

my question is how do i delete the previous child that doesn't exist in Request.childs ?

what i am doing now is i am deleting all the child that belongs to the parent_id and create a new child based on Request, but since child have soft delete on all the deleted child will get stacked in the database.

what currently i am doing

{
   child::where('parent_id',Request->id)->delete();
   foreach($Request->childs as $item){
      child::create['name'=>$item->name,'parent_id'=>$Request->id];
   }
}

what i probably i have to do

foreach($Request->childs as $item){
      if($item->id == null){
         child::create['name'=>$item->name,'parent_id'=>$Request->id];
      }
      child::find($item->id)->update['name'=>$item->name];
   }

i just don't know how to delete the previous child record without deleting everything ?

source https://stackoverflow.com/questions/68550317/mysql-how-do-i-update-parent-and-its-reference-in-backend