how to insert database in codeigniter 3 code example

Example 1: codeigniter where_not_in

$names = array('Frank', 'Todd', 'James');
$this->db->where_not_in('username', $names);
// Produces: WHERE username NOT IN ('Frank', 'Todd', 'James')

Example 2: where group codeigniter

$this->db->select('*')->from('my_table')
        ->group_start()
                ->where('a', 'a')
                ->or_group_start()
                        ->where('b', 'b')
                        ->where('c', 'c')
                ->group_end()
        ->group_end()
        ->where('d', 'd')
->get();

// Generates:
// SELECT * FROM (`my_table`) WHERE ( `a` = 'a' OR ( `b` = 'b' AND `c` = 'c' ) ) AND `d` = 'd'