[web2py] how to delete records from table older than 1 day?

[Amit]

Hi,
I have created table Employe with following fields:
db.define_table(
   'Employee',
   Field('created_on','datetime', default=request.now),
   Field('emp_id'),
   Field('emp_age'),
   Field('emp_address),
)
 inserting data into the table is working fine but when i am trying to 
delete data one day older using below command:

db.executesql('DELETE FROM db.Employee WHERE created_on < date_sub(now(), 
INTERVAL 1 DAY);')

It's not working and i am not getting any error also, so can anybody help 
me resolve this issue.
NOTE: I am using Sqlite database.