creating a window service and writing a method in it and run the service everyday once

Question

hi, I have two databases named abc and xyz. I have to run a job everyday 9 p.m. first I have to check the abc database tables, that if anybody registered a compound in the table within 24hrs of the job running.(like if my job executes today 9 p.m. then the abc database tables should be checked for previous 24 hrs.) Then if I find any compounds registered in the previous 24hrs in the abc database, I should update my xyz database tables. Compounds which are registered before the time period should be skipped(means if they are registered more than 24 hrs previously, those compounds should be skipped). I need a example for this, can anybody send writing this in window services with two assumed tables each in the orresponding databases abc and xyz.The service should be allowed to run everyday once.