convert calender to birthdate

Question

i have a birth date field of type date and when i create form that include that field a calender is displayed into page what i want to do is replace this calender with dropdowns (year,month,day)

i created tables

db.define_table("All_months", SQLField("month","integer") )

and

db.define_table("All_days",
  SQLField("day","integer"))

and

db.define_table("All_years",
  SQLField("year","integer" ))

and in the default.py

This is the whole form:

insert_member_form=SQLFORM(db.member,fields=['first_name','middle_name','last_name','birthdate') birthdate_form=form_factory('b',SQLField('year',db.All_years.year,requires=IS_IN_DB(db,'All_years.year')),SQLField('day',db.All_days.day,requires=IS_IN_DB(db,'All_days.day')), SQLField('Month',db.All_months.month,requires=IS_IN_DB(db,'All_months.month'))
)

finally insert that form to The big form By:

insert_member_form[0].insert(5,birthdate_form[0][0]) insert_member_form[0].insert(5,birthdate_form[0][1]) insert_member_form[0].insert(5,birthdate_form[0][2])

but it displayed an error called "ValueError: invalid literal for int() with base 10: 'upload'".

I dont why??

so pleas could you tell me any other solutions to do what i want?

Thanks in Advance