Schedule Apex

global class Scheduleclass implements schedulable{
    //String cronExp = '0 5 * * * ?';
    //Scheduleclass s = new Scheduleclass();
    //String jobID = system.schedule('Scheduleclass JOB', cronExp, s);
    global void execute(schedulableContext sc){      
 
        Batchclass b = new Batchclass();
        DataBase.executeBatch(b, 100);
        system.debug('b----' +b);
    }
}


Execution:-
------------
system.schedule('Scheduleclass JOB', '0 8 * * * ?', new Scheduleclass());

* This Schedule job will execute every one hour by default.(Suppose today at 06h:08Mins it's executed next schedule will be 07h:08mins... like this it will be schedule)