MySQL DELETE 表别名问题

INSERT INTO `das2`.`variant_car_type` (`service_base_id`, `service_variant_id`, `car_style_id`, `car_type_id`) VALUES ('1000', '2000', '3000', '4000');
INSERT INTO `das2`.`variant_car_type` (`service_base_id`, `service_variant_id`, `car_style_id`, `car_type_id`) VALUES ('1000', '2000', '3001', '4001');
INSERT INTO `das2`.`variant_car_type` (`service_base_id`, `service_variant_id`, `car_style_id`, `car_type_id`) VALUES ('1000', '2001', '3001', '4001');
INSERT INTO `das2`.`variant_car_type` (`service_base_id`, `service_variant_id`, `car_style_id`, `car_type_id`) VALUES ('1000', '2001', '3002', '4002');

delete a1 from variant_car_type as a1, variant_car_type as a2 where a1.service_variant_id = 2001 and a2.service_variant_id = 2000 and a1.car_type_id = a2.car_type_id;

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