What is the required code in phpmyadmin Triggers?

Question

I have three tables in a database

1. videos
2. channels
3. channels2

and trigger code

BEGIN
DECLARE videTimeSum,channel INT;
DECLARE done INT DEFAULT FALSE;
DECLARE cur1 CURSOR FOR Select  sum(videotime) - COALESCE(sum( TIMESTAMPDIFF(Minute,datestart, now() ) ),0)  as videot,channelnumber from videos where flag='0' and channelnumber in (Select channelnumber from channels where flag='0') group by channelnumber order by videot asc limit 1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
If(New.channelnumber is NULL or New.channelnumber ='')
        then   
            SET @channel=(Select channelnumber from channels where flag='0' and channelnumber not in (Select channelnumber from videos where dateend is NULL) limit 1);
            IF(@channel is not NULL and @channel <>'')
                then 
                    SET New.channelnumber=@channel;
                    SET New.playdate=now() + INTERVAL 1 MINUTE;
                    SET New.enddate=now() + INTERVAL New.videotime MINUTE;
            ELSE
                OPEN cur1;
                read_loop: LOOP
                    FETCH cur1 INTO videTimeSum,channel;
                    IF done THEN
                        LEAVE read_loop;
                    ELSE
                        SET New.channelnumber=channel; 
                        SET @videTimeSum=videTimeSum;
                        SET New.playdate = now() + INTERVAL @videTimeSum MINUTE;
                        SET New.enddate = now() + INTERVAL (@videTimeSum + New.videotime)  MINUTE;
                    END IF;
                END LOOP;
                CLOSE cur1;
            END IF;
END IF;

END

I want to auto switch between "channels2" and "channels" tables