How to update table with column set NULL in codeigniter

use this to set null column.it will work, dont forget add false on third parameter SET on active record

$this->db->set('id_parent', 'NULL', false);

you can try this code in 'model', hope it'll work:

public function update_std_marks($id_user) {

    $this->db->set('id_parent', null);
    $this->db->where('id_user', $id_user);
    $this->db->update('user');
}

I was curious, so I wanted to see how CodeIgniter's active record would handle different variations of syntax when working with a null value.

I'll map out several test cases for where() and set() method calls.

The examples below are sorted by ability to render correct SQL, then properly quoted identifiers, then syntax brevity.

Battery of where() tests:

Battery of set() tests:

_{⭐ is my recommendation, ✅ means correct and fully quoted, ⚠️ means it will work but not fully quoted, ❌ means it is incorrect}

Your user table must have the attribute set to is_null in the id_parent field. Otherwise you can't.

The query should be something like

Update table user set id_parent = null where id_user = X

You can set that column nullable with this query:

ALTER TABLE user MODIFY id_parent int(11) null;

Try this for codeigniter:

$fields = array(
                        'id_parent' => array(
                                                         'name' => 'id_parent',
                                                         'type' => 'INT',
                                                ),
);
$this->dbforge->modify_column('user', $fields);

or simply:

$this->db->query('ALTER TABLE user MODIFY id_parent int(11) null;');