private function migrateDateData()
    {
        if (!$this->connection->getSchemaManager()->listTableDetails('ujm_exercise')->hasColumn('start_date')) {
            return; // migration has already been executed
        }

        $this->log('Moving date data from ujm_exercise to claro_resource_node...');

        $startQuery = '
            UPDATE claro_resource_node AS node
            JOIN ujm_exercise AS exo
            ON node.id = exo.resourceNode_id
            SET node.accessible_from = exo.start_date
            WHERE node.accessible_from IS NULL
            AND exo.start_date IS NOT NULL
        ';
        $endQuery = '
            UPDATE claro_resource_node AS node
            JOIN ujm_exercise AS exo
            ON node.id = exo.resourceNode_id
            SET node.accessible_until = exo.end_date
            WHERE node.accessible_until IS NULL
            AND exo.start_date IS NOT NULL
            AND exo.use_date_end = 1
        ';

        $this->connection->exec($startQuery);
        $this->connection->exec($endQuery);
    }