How to check for uniqueness of multiple fields in a database?

I ran into a problem where I don’t know how to check the uniqueness of some fields in the database, I don’t have a field where only 1 element is unique, of course, except for the id, but I can’t compare values by id because this is auto_increment and not manual input.

Question: how to compare if there are fields label, table_id

                    $this->db->table('context')->insert([
                        'type_flow' => $node['name'],
                        'title' => $node['data']['title'],
                        'label' => $item['label'],
                        'type' =>  $item['type'],
                        'value' => $item['value'],
                        'table_id' => $node['id'],
                    ]);

I need to implement this in codeigniter and if there is a comparison method, can you tell me of course I think I could manually try to extract fields from the database and compare but I think the code would not be entirely correct

If you need more data, please write in the comments.

my try:

$db_conn = $this->model->where('type_flow', $item['field'])->where('table_id', $node['id'])->where('type_flow', 'conditions')->first() ? true : false;
                    if (!$db_conn) {
                        $this->db->table('context')->insert([
                            'type_flow' => $node['name'],
                            'title' => $node['data']['title'],
                            'label' => $item['field'],
                            'type' =>  $item['type'],
                            'value' => $item['value'],
                            'table_id' => $node['id'],
                        ]);
                    }