[BUG]: `\Phalcon\Mvc\Model\Manager` converts `NOT BETWEEN` operator to `BETWEEN NOT`

[toramanlis]

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Describe the bug
Models manager gets a query with the NOT BETWEEN operation in the WHERE clause, it converts the operator to BETWEEN NOT and receives an error on execution.

The issue stems from \Phalcon\Mvc\Model\Query::getExpression(). It resolves the operator to BETWEEN NOT at phalcon/Mvc/Model/Query.zep#L2063-L2069

To Reproduce

• Create a table with a field compatible with the BETWEEN operator
• Write a query with a NOT BETWEEN operator in the WHERE clause
• Execute the query through the \Phalcon\Mvc\Model\Manager service
• Check the final query that's been executed and see the switch to BETWEEN NOT

$q = 'SELECT created_at FROM [Models\Orders] WHERE created_at NOT BETWEEN "2025-10-02 00:00:00" AND "2025-10-02 23:59:59"';

        try {
            $this->modelsManager->executeQuery($q);
        } catch (Exception $e) {
            $sql = $this->db->getSQLStatement();
        }

The variable $sql now has the operator changed to BETWEEN NOT

Expected behavior
The operator should remain as NOT BETWEEN, BETWEEN NOT is not a valid usage and fails the execution.

Details

• Phalcon version: 4.x, 5.x
• PHP Version: 7.x, 8.x
• Server: Nginx