CREATE PROCEDURE `get_customer`(IN customer_id INT, OUT customer_name VARCHAR(50))
BEGIN
SELECT name INTO customer_name FROM customers WHERE id = customer_id;
END;

CREATE TABLE `customers` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `email` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4;
INSERT INTO `customers` (`name`, `email`) VALUES
('Alice', 'alice@example.com'),
('Bob', 'bob@example.com'),
('Charlie', 'charlie@example.com');
创建一个名为customers的表，并插入3条顾客记录。该表包含id、name和email字段，其中id为自增主键。

-- 调用名为`get_customer`的存储过程，并将参数值设置为1和@customer_name变量
CALL get_customer(1, @customer_name);
-- 查看存储在@customer_name变量中的结果
SELECT @customer_name;