Custom Employee Number - Personalization

Dear Gurus

As we are implementing HRMS, client needs the employee number should be generated automatically. There are two types of employee, one type of employee number should be A1000 & other should be B1000. I have given the employee number generation as manual in the BG setup. and added a personalization with the below code.

Condition : PERSON.D_PTU_USER_PERSON_TYPE= 'Employee'

Value

= select 'A' || (nvl(max(to_number(substr(employee_number,2))),999)+1)

from per_all_people_f

where EMPLOYEE_NUMBER like 'A%'

and business_group_id = 81

One more point, i want to include that, Multiple BG & iRecruitment module going to be implemented. so applicants can be hired as employee. Will it make any problem.