如果不存在记录，如何创建一个事件来删除表和另一个事件

Question

我正在创建一个带有事件的总线表来维护数据。如果总线表中不存在记录，是否可以通过DropBusEvent事件丢弃该表和autoDelete事件？

        stt.execute("CREATE TABLE IF NOT EXISTS bus"
                + "(id INT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY,"
                + "mac VARCHAR(30) NOT NULL UNIQUE,"
                + "route int(11) NOT NULL,"
                + "latitude FLOAT(10,6) NOT NULL,"
                + "longitude FLOAT(10,6) NOT NULL,"
                + "created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP)");

        stt.execute("CREATE EVENT IF NOT EXISTS  AutoDelete "
                + "ON SCHEDULE EVERY 3 MINUTE "
                + "DO "
                + "DELETE FROM bus WHERE created_at < (NOW() - INTERVAL 3 MINUTE)");

        // I tried this statement here but it does not work.
        stt.execute("CREATE EVENT IF NOT EXITS DropBusTable "
                + "Do "
                + "DROP TABLES IF EXISTS bus");

我要去找You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'EXITS DropBusTableDROP TABLES IF EXISTS bus' at line 1

Answer 1

您的语法有一个错误：

行中使用EXITS而不是EXISTS

stt.execute("CREATE EVENT IF NOT EXITS DropBusTable "