错误1451无法从父表中删除记录

Question

大家好，我正在尝试删除一条记录。但是由于外键约束而不允许我

我尝试执行的操作是 （所有卡号都是假的）

DELETE FROM payment_method
WHERE card_no = 42218345;

表结构：

CREATE TABLE  payment_details  (
   card_no  int(8) NOT NULL,
   customer_id  int(50)  NOT NULL AUTO_INCREMENT,
   CVV  int(3) NOT NULL,
   card_type  ENUM ('Visa', 'Amex', 'American Express', 'Mastercard') NOT NULL,
   expiry_date  DATE NOT NULL,
   PRIMARY KEY(card_no),
   KEY customer_idfk1 (customer_id),
   CONSTRAINT customer_idfk1 FOREIGN KEY (customer_id) REFERENCES customers (customer_id) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8

和

CREATE TABLE  customers  (
   customer_id  int(50)  NOT NULL AUTO_INCREMENT,
   fname  varchar(20) NOT NULL,
   lname  varchar(20) NOT NULL,
   dateOfBirth date NOT NULL,
   address  varchar(30) NOT NULL,
   city  varchar(20) NOT NULL,
   county  ENUM('Armagh','Carlow','Cavan','Clare','Cork','Derry','Donegal','Down','Dublin','Fermanagh','Galway','Kerry','Kildare','Kilkenny','Laois','Leitrim','Limerick','Longford','Louth','Mayo','Meath','Monaghan','Offaly','Roscommon','Sligo','Tipperary','Tyrone','Waterford','Westmeath','Wexford','Wicklow') NOT NULL,
   phone  int(10) NOT NULL,
   email  varchar(20) NOT NULL,
   payment_method  ENUM ('Visa', 'Amex', 'Cash', 'American Express', 'Mastercard') NOT NULL,
   valid_licence varchar(5) NOT NULL,
   status  varchar(10),
   PRIMARY KEY (customer_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

错误是：

  

1451-无法删除或更新父行：外键约束失败（g00337857abu。payment_details，CONSTRAINT customer_idfk1

     

外键（customer_id）参考customers（customer_id））

有人知道为什么它不允许我删除此记录。

发现了第一个错误

现在我正尝试从客户表中删除

DELETE FROM customers
WHERE customer_id = 1

  

错误-＃1451-无法删除或更新父行：外键   约束失败（g00337857abu。payment_details，约束   customer_idfk1外键（customer_id）参考customers   （customer_id）