【MySQL】Event事件与游标

CREATE PROCEDURE `test`.`new_procedure` ()
BEGIN
  -- 需要定义接收游标数据的变量 
  DECLARE a CHAR(16);
  -- 声明游标的结束标志
  DECLARE done INT DEFAULT FALSE;
  -- 将所需数据赋予游标，游标必须定义在变量/条件后，handler前；否则会报错。
　-- ERROR 1337 (42000): Variable or condition declaration after cursor or handler declaration
  DECLARE cur CURSOR FOR SELECT i FROM test.t;
  -- 将结束标志绑定到游标，如果捕获到not found异常时就会将变量done设置为TRUE，done=TRUE可以当作循环跳出条件
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
  -- 打开游标
  OPEN cur;
  
  -- 开始循环
  read_loop: LOOP
    -- 提取游标里的数据，这里只有一个，也可以有多个，例如fetch <游标名> into <变量1>,<变量2>
    FETCH cur INTO a;
    -- 声明结束的时候
    IF done THEN
      LEAVE read_loop;
    END IF;
 
   -- 这里做你想做的循环的事件
    sql;

  END LOOP;
  -- 关闭游标
  CLOSE cur;

END

drop procedure if exists test_proce2;  
create procedure test_proce2()  
begin  
    declare temp_id int(11);  
    declare temp_time datetime;  
    declare isFinished boolean default false;  
    declare test_cursor cursor for select id,time from test;  
    declare continue handler for not found set isFinished=true;  
    open test_cursor;  
    repeat  
        fetch test_cursor into temp_id,temp_time;  
        if not isFinished then  
            select concat(concat(temp_id,":"),temp_time);  
        end if;  
    until isFinished end repeat;  
   close test_cursor;  
  end  

 drop procedure if exists test_proce3;  
create procedure test_proce3()  
begin  
    declare temp_id int(11);  
    declare temp_time datetime;  
    declare isFinished boolean default false;  
    declare test_cursor cursor for select id,time from test;  
    declare continue handler for not found set isFinished=true;  
    open test_cursor;  
    test_loop:loop  
        fetch test_cursor into temp_id,temp_time;  
        if isFinished then  
            leave test_loop;  
        end if;  
        //若该if语句放在fetch后面，该循环为while型；若该if语句紧接在end loop前该循环为do while型。  
        select concat(concat(temp_id,":"),temp_time);  
    end loop test_loop;  
  close test_cursor;  
 end  

DELIMITER $$
CREATE EVENT `report`.`monitor_user4cx` ON SCHEDULE EVERY 15 MINUTE  DO 
BEGIN
DECLARE cx_id INT(10);
DECLARE t_query VARCHAR(500);
DECLARE done INT DEFAULT FALSE;
DECLARE cur CURSOR FOR SELECT id FROM information_schema.PROCESSLIST WHERE `USER`=‘cx‘ AND `TIME` > 600 AND `Command`=‘Query‘;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur;
read_loop:LOOP
FETCH cur INTO cx_id;
IF done THEN
LEAVE read_loop;
END IF;
SELECT t.trx_query,t.trx_started,p.`USER` FROM information_schema.PROCESSLIST p INNER JOIN information_schema.innodb_trx t ON p.id=t.trx_mysql_thread_id WHERE p.id=cx_id INTO @t_query,@t_time,@p_user;
INSERT INTO test.monitor_user4cx(`p_id`,`start_time`,`user`,`time`,`query`) VALUES (cx_id,@t_time,@p_user,NOW(),@t_query);
KILL cx_id;
END LOOP;
CLOSE cur;
END$$
DELIMITER ;