使用 MySQL 触发器更新客户余额

Question

我需要一些帮助来理解触发器及其工作原理。我有 3 个表：

Customers
Id | Balance

Invoices
Id | Custid | Amount

Payments
Id | CustId | Amount

我有插入发票的插入语句：

$this->db->insert('invoices', array(
            'CustomerId' => $data['customerId'],
            'Description' => $data['Description'],
            'DateCreated' => $data['DateCreated'],
            'Amount' => $data['Amount']
        ));

并且需要在插入后更新客户余额。同样，在插入或创建付款后。我需要从客户余额中扣除。

public function createPayment($data) {
        $this->db->insert('payments', array(
            'CustomerId' => $data['customerid'],
            'DateCreated' => date("Y-m-d H:i:s"),
            'Amount' => $data['amount']
        ));
    }

如果您能协助创建这些触发器，我们将不胜感激。

Answer 1

您需要两个触发器 - 一个用于发票 table:

delimiter //
CREATE TRIGGER add_invoice_to_balance AFTER INSERT ON invoices
FOR EACH
ROW
BEGIN
    UPDATE Customers SET balance = balance + NEW.Amount
      WHERE Customers.id = NEW.custid;
END;
//
delimiter;

还有一个用于付款 table:

delimiter //
CREATE TRIGGER add_payment_to_balance AFTER INSERT ON payments
FOR EACH
ROW
BEGIN
    UPDATE Customers SET balance = balance - NEW.Amount
      WHERE Customers.id = NEW.custid;
END;
//
delimiter ;

fiddle here

使用 MySQL 触发器更新客户余额

Using MySQL triggers to update customers balance

mysql

triggers