mysql 做队列

-- 创建队列表
CREATE TABLE queue (
    id INT AUTO_INCREMENT PRIMARY KEY,
    message TEXT NOT NULL,
    status ENUM('pending', 'processing', 'completed') DEFAULT 'pending',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

-- 插入消息到队列
INSERT INTO queue (message) VALUES ('Hello, World!');

-- 从队列中取出消息并处理（假设使用存储过程）
DELIMITER //
CREATE PROCEDURE process_queue()
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE msg TEXT;
    DECLARE cur CURSOR FOR SELECT message FROM queue WHERE status = 'pending' LIMIT 1;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

    OPEN cur;

    read_loop: LOOP
        FETCH cur INTO msg;
        IF done THEN
            LEAVE read_loop;
        END IF;

        -- 处理消息（这里仅打印消息）
        SELECT msg;

        -- 更新消息状态为处理中
        UPDATE queue SET status = 'processing' WHERE message = msg;

        -- 模拟消息处理完成
        UPDATE queue SET status = 'completed' WHERE message = msg;
    END LOOP;

    CLOSE cur;
END //
DELIMITER ;

-- 调用存储过程处理队列中的消息
CALL process_queue();