A quick example of a custom model with a custom query

customModel.php

<?php

use GroceryCrud\Core\Model;
use Zend\Db\Sql\Sql;

class customModel extends Model {

    public function customInsert($insertId)
    {
        $sql = new Sql($this->adapter);
        $select = $sql->select()
            ->columns(['customer_id'])
            ->from('customers');

        $select->where([
            'customers.customer_id = ?' => $insertId
        ]);

        $row = $this->getRowFromSelect($select, $sql);

        if ($row === null) {
            return false;
        }

        $sql = new Sql($this->adapter);
        $update = $sql->update('customers');
        $update->where([
            'customer_id = ?' => $insertId
        ]);

        $update->set([
            'customer_name' => 'Patata'
        ]);

        $statement = $sql->prepareStatementForSqlObject($update);
        return $statement->execute();
    }
}