Question

我在子表上应用了DELETE CASCADE和UPDATE CASCADE约束。

alter table table_product_categories add constraint fk_product_id1 foreign key (product_id) references table_products (product_id) on delete cascade;

alter table table_product_categories add constraint fk_product_id2 foreign key (product_id) references table_products (product_id) on update cascade;

现在尝试在父表中删除时：

DELETE FROM table_products WHERE `table_products`.`product_id` = 1819

出现此错误：

MySQL说：文档

1451 - 无法删除或更新父行：外键约束失败（`table_product_categories`，CONSTRAINT`fk_product_id1` FOREIGN KEY（`product_id`）REFERENCES`table_products`（`product_id`）ON UPDATE CASCADE）

尝试更新父表时

UPDATE  `wokoshop`.`table_products` SET  `product_id` =  '1' WHERE `table_products`.`product_id` =1819

出现此错误：

1452 - 无法添加或更新子行：外键约束失败（`wokoshop` .table_product_categories`，CONSTRAINT`fk_product_id2` FOREIGN KEY（`product_id`）REFERENCES`table_products`（`product_id`）ON DELETE CASCADE ）

错误的原因是什么以及如何解决？

Answer 1

不要创建两个约束，而是使用两个CASCADE选项的单个约束：

alter table table_product_categories 
    add constraint fk_product_id1 foreign key (product_id) 
    references table_products (product_id) 
    on delete cascade on update cascade;

应用DELETE和UPDATE级联后，无法从父表中删除/更新

1 个答案: