为什么它没有显示这样的专栏

Question

/* Triggers*/
create table acustomer( id integer primary key, desc text, last_order_id integer);
create table bcustomer ( id integer primary key, item_id int, customer_id int, quan int, price int);
insert into acustomer (desc) values ( 'rohan');
insert into acustomer (desc) values ('mohan');
insert into acustomer (desc) values ('sohan');
select * from acustomer;
create trigger ccustomer after insert on bcustomer
begin
    update acustomer set last_order_id = NEW.id where acustomer.id = NEW.customer_id;
end;
insert into bcustomer (item_id, customer_id, quan, price) values (1, 2, 3, 4);
insert into bcustomer (item_id, customer_id, quan, price) values (5, 6, 7, 8);
insert into bcustomer (item_id, customer_id, quan, price) values (8, 9, 10, 20);
insert into bcustomer (item_id, customer_id, quan, price) values (4, 12, 19, 13);

select * from acustomer;
select * from bcustomer;

#on在表Ccustomer中执行插入，它显示错误：无列：new.customer.id

Answer 1

您对 bcustomer 表的最后一个插入件是

insert into bcustomer (item_id, customer_id, quan, price) values (4, 12, 19, 13);

customer中没有任何匹配的 last_order_id 。

如果您将运行

insert into bcustomer (item_id, customer_id, quan, price) values (4, 1, 19, 13);

customer_id = 1 ，它将更新您的 customer 表，因为它具有匹配的ID，即 1 。

尝试此