mysql - SQL 事件的语法问题

Question

我正在尝试在 MySQL 上运行此代码:

SET GLOBAL event_scheduler = ON;
CREATE EVENT timer
ON SCHEDULE EVERY 1 MINUTE
DO // this is the line of error
IF CURRENT_TIMESTAMP > timer THEN UPDATE users SET online = '0' WHERE CURRENT_TIMESTAMP > timer;
END IF;

但它返回:#1064 - 第 4 行“”附近的语法错误。 错误在哪里？

Answer 1

As with stored routines, you can use compound-statement syntax in the DO clause by using the BEGIN and END keywords, as shown在该页面的示例中

delimiter |

CREATE EVENT e_daily
    ON SCHEDULE
      EVERY 1 DAY
    COMMENT 'Saves total number of sessions then clears the table each day'
    DO
      BEGIN
        INSERT INTO site_activity.totals (time, total)
          SELECT CURRENT_TIMESTAMP, COUNT(*)
            FROM site_activity.sessions;
        DELETE FROM site_activity.sessions;
      END |

delimiter ;

你的 SQL 如何与这个想法一起工作的想法是:

SET GLOBAL event_scheduler = ON;

-- change the delimiter so you can embed ; in your event_body
delimiter |

CREATE EVENT timer
    ON SCHEDULE
      EVERY 1 MINUTE
    DO
      BEGIN
          IF CURRENT_TIMESTAMP > timer
            THEN UPDATE users SET online = '0' WHERE CURRENT_TIMESTAMP > timer;
          END IF 
      END |

-- reset the delimiter
delimiter ;