Uses of datediff and >= in stored procedure

declare @jobid varchar(50)
declare @empid varchar(50)
declare @diffyear varchar(50)
set @jobid='0'
set @empid='0'

select @jobid=job_id from emp_profile where job_id=@job_id 
select @empid=@emp_email_id from emp_profile where emp_email_id=@emp_email_id

select @diffyear= datediff(yy,@dob,@date_of_joining)


if @empid='0' and @jobid='0' and @diffyear>=22
begin

insert into emp_profile(job_id,emp_name,emp_desig,emp_contact_no,emp_email_id,date_of_joining,
marital_status,dob,sex,emp_address,city,state,country,zip_code)

values(@job_id,@emp_name,@emp_desig,@emp_contact_no,@emp_email_id,@date_of_joining,
@marital_status,@dob,@sex,@emp_address,@city,@state,@country,@zip_code)	


return 11
end
else if @empid='0' and @jobid<>'0' 
begin
return 22
end
else if @empid<>'0' and @jobid='0' 

begin 
return 33
end
else if @empid<>'0' and @jobid<>'0' 

begin 
return 44
end
else if @diffyear<22
begin  
return 55
end