Importing voucher codes from Espresso Store to Verbb Gift Vouchers
I think you'd be better off creating a quick module with a controller method to import your voucher codes, to make sure Craft (and Verbb Gift) create all the necessary table rows for the vouchers to work (code is untested, but just to get an idea):

use verbb\giftvoucher\elements\Voucher;

public function actionCopyVouchers()
{
    $esVouchers = Craft::$app-&gt;db-&gt;createCommand()-&gt;select('*')-&gt;from('es_vouchers')-&gt;all();

    foreach ($esVouchers as $esVoucher) {
        $voucher = new Voucher();
        $voucher-&gt;field = $esVoucher-&gt;field;
        $voucher-&gt;anotherField = $esVoucher-&gt;anotherField;
        // ... Whatever your voucher needs ...

        Craft::$app-&gt;getElements()-&gt;saveElement($voucher);
    }
}