CREATE
    [DEFINER = user]
    EVENT
    [IF NOT EXISTS]
    event_name
    ON SCHEDULE schedule
    [ON COMPLETION [NOT] PRESERVE]
    [ENABLE | DISABLE | DISABLE ON {REPLICA | SLAVE}]
    [COMMENT 'string']
    DO event_body;

schedule: {
    AT timestamp [+ INTERVAL interval] ...
  | EVERY interval
    [STARTS timestamp [+ INTERVAL interval] ...]
    [ENDS timestamp [+ INTERVAL interval] ...]
}

interval:
    quantity {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |
              WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |
              DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}

此语句用于创建和调度新事件。除非启用了事件调度器，否则事件不会运行。如需有关检查事件调度器状态以及在必要时启用它的信息，请参见 第 27.4.2 节，“事件调度器配置”。This statement creates and schedules a new event. The event does not run unless the Event Scheduler is enabled. For information about checking Event Scheduler status and enabling it if necessary, see Section 27.4.2, “Event Scheduler Configuration”.

CREATE EVENT 需要在要创建事件的模式中具有 EVENT 权限。如果存在 DEFINER 子句，则所需权限取决于 user 值，如 第 27.6 节，“存储对象访问控制” 中所述。CREATE EVENT requires the EVENT privilege for the schema in which the event is to be created. If the DEFINER clause is present, the privileges required depend on the user value, as discussed in Section 27.6, “Stored Object Access Control”.

有效 CREATE EVENT 语句的最低要求如下：The minimum requirements for a valid CREATE EVENT statement are as follows:

这是一个最小 CREATE EVENT 语句的示例：This is an example of a minimal CREATE EVENT statement:

CREATE EVENT myevent
    ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 HOUR
    DO
      UPDATE myschema.mytable SET mycol = mycol + 1;

前面的语句创建了一个名为 myevent 的事件。此事件会在创建后一小时执行一次，通过运行 SQL 语句将 myschema.mytable 表的 mycol 列的值加 1。The previous statement creates an event named myevent. This event executes once—one hour following its creation—by running an SQL statement that increments the value of the myschema.mytable table's mycol column by 1.

event_name 必须是有效的 MySQL 标识符，最大长度为 64 个字符。事件名称不区分大小写，因此在同一模式中不能有两个事件分别命名为 myevent 和 MyEvent。通常，事件名称的规则与存储例程名称相同。参见 第 11.2 节，“模式对象名称”。The event_name must be a valid MySQL identifier with a maximum length of 64 characters. Event names are not case-sensitive, so you cannot have two events named myevent and MyEvent in the same schema. In general, the rules governing event names are the same as those for names of stored routines. See Section 11.2, “Schema Object Names”.

事件与模式关联。如果 event_name 中未指明任何模式，则假定为默认（当前）模式。要在特定模式中创建事件，请使用 schema_name.event_name 语法为事件名称加上模式限定符。An event is associated with a schema. If no schema is indicated as part of event_name, the default (current) schema is assumed. To create an event in a specific schema, qualify the event name with a schema using schema_name.event_name syntax.

DEFINER 子句指定在事件执行时检查访问权限所使用的 MySQL 帐号。如果存在 DEFINER 子句，user 值应为 MySQL 帐号，格式为 'user_name'@'host_name'、CURRENT_USER 或 CURRENT_USER()。允许的 user 值取决于您拥有的权限，如 第 27.6 节，“存储对象访问控制” 中所讨论的内容。有关事件安全的更多信息，也请参见该节。The DEFINER clause specifies the MySQL account to be used when checking access privileges at event execution time. If the DEFINER clause is present, the user value should be a MySQL account specified as 'user_name'@'host_name', CURRENT_USER, or CURRENT_USER(). The permitted user values depend on the privileges you hold, as discussed in Section 27.6, “Stored Object Access Control”. Also see that section for additional information about event security.

如果省略 DEFINER 子句，则默认的定义者为执行 CREATE EVENT 语句的用户。这与显式指定 DEFINER = CURRENT_USER 相同。If the DEFINER clause is omitted, the default definer is the user who executes the CREATE EVENT statement. This is the same as specifying DEFINER = CURRENT_USER explicitly.

在事件体内，CURRENT_USER 函数返回在事件执行时用于检查权限的账户，即 DEFINER 用户。有关事件中用户审计的信息，请参见 第 8.2.23 节，“基于 SQL 的账户活动审计”。Within an event body, the CURRENT_USER function returns the account used to check privileges at event execution time, which is the DEFINER user. For information about user auditing within events, see Section 8.2.23, “SQL-Based Account Activity Auditing”.

IF NOT EXISTS 对 CREATE EVENT 的含义与对 CREATE TABLE 的含义相同：如果同一模式中已经存在名为 event_name 的事件，则不执行任何操作，也不会产生错误。（但是，在这种情况下会生成警告。）IF NOT EXISTS has the same meaning for CREATE EVENT as for CREATE TABLE: If an event named event_name already exists in the same schema, no action is taken, and no error results. (However, a warning is generated in such cases.)

ON SCHEDULE 子句确定事件定义的 event_body 何时、多久以及重复的频率。这个子句有两种形式：The ON SCHEDULE clause determines when, how often, and for how long the event_body defined for the event repeats. This clause takes one of two forms:

ON SCHEDULE 子句可以使用包含内置 MySQL 函数和用户变量的表达式来获取其中的任何 timestamp 或 interval 值。在这些表达式中不得使用存储函数或可加载函数，也不得引用任何表；但是，可以使用 SELECT FROM DUAL。这对于 CREATE EVENT 和 ALTER EVENT 语句都适用。在这些情况下，特别禁止引用存储函数、可加载函数和表，否则会出错（参见 Bug #22830）。The ON SCHEDULE clause may use expressions involving built-in MySQL functions and user variables to obtain any of the timestamp or interval values which it contains. You may not use stored functions or loadable functions in such expressions, nor may you use any table references; however, you may use SELECT FROM DUAL. This is true for both CREATE EVENT and ALTER EVENT statements. References to stored functions, loadable functions, and tables in such cases are specifically not permitted, and fail with an error (see Bug #22830).

ON SCHEDULE 子句中的时间使用当前会话的 time_zone 值解释。这成为事件的时区；即用于事件调度并在事件执行时生效的时区。这些时间会转换为 UTC 并与事件时区一同存储。这样无论服务器时区或夏令时后续如何变化，事件执行都可以按定义进行。有关事件时间表示的更多信息，请参见 第 27.4.4 节，“事件元数据”。另请参见 第 15.7.7.19 节，“SHOW EVENTS 语句” 和 第 28.3.14 节，“INFORMATION_SCHEMA EVENTS 表”。Times in the ON SCHEDULE clause are interpreted using the current session time_zone value. This becomes the event time zone; that is, the time zone that is used for event scheduling and is in effect within the event as it executes. These times are converted to UTC and stored along with the event time zone internally. This enables event execution to proceed as defined regardless of any subsequent changes to the server time zone or daylight saving time effects. For additional information about representation of event times, see Section 27.4.4, “Event Metadata”. See also Section 15.7.7.19, “SHOW EVENTS Statement”, and Section 28.3.14, “The INFORMATION_SCHEMA EVENTS Table”.

通常，事件一旦过期，它会立即被丢弃。你可以通过指定 ON COMPLETION PRESERVE。使用 ON COMPLETION NOT PRESERVE 只是让默认的非持久行为显式化。Normally, once an event has expired, it is immediately dropped. You can override this behavior by specifying ON COMPLETION PRESERVE. Using ON COMPLETION NOT PRESERVE merely makes the default nonpersistent behavior explicit.

你可以创建事件但阻止其激活，方法是 DISABLE 关键字。或者，你也可以使用 ENABLE，将默认状态显式化为活跃状态。这与 ALTER EVENT“（参见 第 15.1.3 节，”ALTER EVENT Statement“）。You can create an event but prevent it from being active using the DISABLE keyword. Alternatively, you can use ENABLE to make explicit the default status, which is active. This is most useful in conjunction with ALTER EVENT (see Section 15.1.3, “ALTER EVENT Statement”).

第三个值也可以替代 ENABLE 或 DISABLEDISABLE ON REPLICA REPLICA 设置为副本事件状态，表示该事件是在复制源服务器创建并复制到副本，但未在副本上执行。参见 第 19.5.1.16 节，“调用特征的复制”。A third value may also appear in place of ENABLE or DISABLE; DISABLE ON REPLICA is set for the status of an event on a replica to indicate that the event was created on the replication source server and replicated to the replica, but is not executed on the replica. See Section 19.5.1.16, “Replication of Invoked Features”.

DISABLE ON REPLICA REPLICA 取代了 DISABLE ON SLAVE后者已被弃用，因此未来版本的 MySQL 可能会被移除。DISABLE ON REPLICA replaces DISABLE ON SLAVE, which is deprecated, and thus subject to removal in a future version of MySQL.

您可以使用 COMMENT。comment 可以是您希望使用最多 64 字符的字符串来描述事件。注释文本作为字符串文字，必须被引号包围。You may supply a comment for an event using a COMMENT clause. comment may be any string of up to 64 characters that you wish to use for describing the event. The comment text, being a string literal, must be surrounded by quotation marks.

DO 子句指定事件所执行的动作，包含一个 SQL 语句。几乎任何可在存储例程中使用的有效 MySQL 语句，也可以用作调度事件的动作语句。（参见 第 27.8 节，“对存储程序的限制”。）例如，以下事件 e_hourly 每小时删除 sessions，该表属于 site_activity schema：The DO clause specifies an action carried by the event, and consists of an SQL statement. Nearly any valid MySQL statement that can be used in a stored routine can also be used as the action statement for a scheduled event. (See Section 27.8, “Restrictions on Stored Programs”.) For example, the following event e_hourly deletes all rows from the sessions table once per hour, where this table is part of the site_activity schema:

CREATE EVENT e_hourly
    ON SCHEDULE
      EVERY 1 HOUR
    COMMENT 'Clears out sessions table each hour.'
    DO
      DELETE FROM site_activity.sessions;

MySQL 存储 sql_mode 系统变量设置，并在事件开始执行时始终执行该设置，无论当前服务器 SQL 模式如何。MySQL stores the sql_mode system variable setting in effect when an event is created or altered, and always executes the event with this setting in force, regardless of the current server SQL mode when the event begins executing.

CREATE EVENT 语句，包含包含 ALTER EVENT statement in 其 DO 子句似乎成功;然而，当服务器尝试执行由此产生的定时事件时，执行会以错误告终。A CREATE EVENT statement that contains an ALTER EVENT statement in its DO clause appears to succeed; however, when the server attempts to execute the resulting scheduled event, the execution fails with an error.

事件所属的模式是 DO 子句中表引用的默认模式。对其他模式中表的任何引用必须使用适当的模式名称进行限定。The schema to which an event belongs is the default schema for table references in the DO clause. Any references to tables in other schemas must be qualified with the proper schema name.

与存储例程一样，你可以在 DO 子句中使用复合语句语法，通过使用 BEGIN 和 END 关键字，如下所示：As with stored routines, you can use compound-statement syntax in the DO clause by using the BEGIN and END keywords, as shown here:

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 ;

此示例使用 delimiter 命令更改语句分隔符。请参见 第 27.1 节，“定义存储程序”。This example uses the delimiter command to change the statement delimiter. See Section 27.1, “Defining Stored Programs”.

在事件中可以使用更复杂的复合语句，例如存储例程中使用的语句。此示例使用了局部变量、错误处理程序和流程控制构造：More complex compound statements, such as those used in stored routines, are possible in an event. This example uses local variables, an error handler, and a flow control construct:

delimiter |

CREATE EVENT e
    ON SCHEDULE
      EVERY 5 SECOND
    DO
      BEGIN
        DECLARE v INTEGER;
        DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN END;

        SET v = 0;

        WHILE v < 5 DO
          INSERT INTO t1 VALUES (0);
          UPDATE t2 SET s1 = s1 + 1;
          SET v = v + 1;
        END WHILE;
    END |

delimiter ;

无法直接向事件传递参数或从事件接收参数；但是，可以在事件中调用带参数的存储例程：There is no way to pass parameters directly to or from events; however, it is possible to invoke a stored routine with parameters within an event:

CREATE EVENT e_call_myproc
    ON SCHEDULE
      AT CURRENT_TIMESTAMP + INTERVAL 1 DAY
    DO CALL myproc(5, 27);

如果事件的定义器拥有足够的权限来设置全局系统变量（参见 第 7.1.9.1 节，“系统变量特权”），事件可以读取和写入全局变量。由于授予此类权限存在滥用风险，使用时必须格外谨慎。If an event's definer has privileges sufficient to set global system variables (see Section 7.1.9.1, “System Variable Privileges”), the event can read and write global variables. As granting such privileges entails a potential for abuse, extreme care must be taken in doing so.

通常，任何在存储例程中有效的语句都可用于事件执行的动作语句。有关存储例程中允许语句的更多信息，请参见 第 27.2.1 节，“存储例程语法”。无法作为存储例程的一部分创建事件，也无法通过其他事件创建事件。Generally, any statements that are valid in stored routines may be used for action statements executed by events. For more information about statements permissible within stored routines, see Section 27.2.1, “Stored Routine Syntax”. It is not possible to create an event as part of a stored routine or to create an event by another event.