Update posted columns only - php

Question

I am working with rest API in CodeIgniter
I am working with update API so I want to update only those columns/fields which I sent via postman,
for example, if I sent only first_name and last_name then only these columns should be updated not all columns,
but current code updating all columns, Here is my code where I am wrong?
public function update_userrecords()
{
$add_data['user_id'] = ($this->input->post('user_id') && !empty($this->input->post('user_id'))) ? $this->input->post('user_id') : NULL;
$add_data['first_name'] = ($this->input->post('first_name') && !empty($this->input->post('first_name'))) ? $this->input->post('first_name') : NULL;
$add_data['last_name'] = ($this->input->post('last_name') && !empty($this->input->post('last_name'))) ? $this->input->post('last_name') : NULL;
$add_data['password'] = ($this->input->post('password') && !empty($this->input->post('password'))) ? $this->input->post('password') : NULL;
$t=time();
$data = array(
'first_name'=>$add_data['first_name'],
'last_name'=>$add_data['last_name'],
'password'=>md5($add_data['password']),
'updated_on'=>$t,
);
$this->db->where('id',$add_data['user_id']);
$this->db->update('users', $data);
}

Answer 1

You can use this way
Set you input field in new array and update that array. I have added one field in $insert_data. you can add as much you want.
public function update_userrecords()
{
$add_data['user_id'] = ($this->input->post('user_id') && !empty($this->input->post('user_id'))) ? $this->input->post('user_id') : NULL;
$insert_data = [];
if($this->input->post('first_name') && !empty($this->input->post('first_name'))) {
$insert_data['first_name'] = $this->input->post('user_id');
}
$t=time();
$this->db->where('id',$add_data['user_id']);
$this->db->update('users', $insert_data);
}