删除程序不会运行并给出错误？

Question

我创建了一个从三个表中删除数据的过程，这些表都与外键链接，但不会运行。这里是程序。

PROCEDURE remove_customer (customer_id VARCHAR2) IS 
BEGIN 
DELETE FROM order_line 
WHERE order_line.order_id = placed_order.order_id; 
DELETE FROM placed_order 
WHERE placed_order.customer_id = customer.customer_id; 
DELETE FROM customer 
WHERE customer.customer_id = remove_customer.customer_id; 
total_customers := total_customers - 1; 
END; 

这里是三个表格的结构。任何人知道我为什么会得到错

customer(
    Customer_ID INTEGER NOT NULL, 
    Country VARCHAR(15), 
    First_Name VARCHAR(30), 
    Last_Name VARCHAR(30), 
    CONSTRAINT pk_customer PRIMARY KEY (Customer_ID) 
); 


    placed_order(
    order_id INTEGER NOT NULL, 
    order_date VARCHAR(15), 
    fk1_Customer_ID INTEGER NOT NULL, 
    fk2_Employee_ID INTEGER NOT NULL, 
    fk3_order_type_id INTEGER NOT NULL, 
    CONSTRAINT pk_placed_order PRIMARY KEY (order_id) 
); 


    order_line(
    order_line_id INTEGER NOT NULL, 
    fk1_order_id INTEGER NOT NULL, 
    fk2_product_id INTEGER NOT NUL, 
    CONSTRAINT pk_order_line PRIMARY KEY (order_line_id) 
); 

这是两个错误的回归。

ORA-00904： “PLACED_ORDER” “ORDER_ID”：无效identifierCompilation失败，行30

ORA-00904： “用户”， “CUSTOMER_ID”：无效identifierCompilation失败，行32

Answer 1

你不能只需在DELETE语句中引用其他表中的列即可。每条语句都需要从参数值customer_id开始。这应该做你想要的：

PROCEDURE remove_customer (customer_id VARCHAR2) IS 
BEGIN 

    DELETE FROM order_line 
    WHERE order_line.order_id in 
    (SELECT order_id FROM placed_order 
    WHERE placed_order.customer_id = remove_customer.customer_id 
); 

    DELETE FROM placed_order 
    WHERE placed_order.customer_id = remove_customer.customer_id; 

    DELETE FROM customer 
    WHERE customer.customer_id = remove_customer.customer_id; 

    total_customers := total_customers - 1; 

END;