Migrate data from one table to the other

I have two tables and I have to transfer data from one to the other.

Table 1: employees

home_address string

Table 2 emp_address

address      string 
emp_id       int 
is_permanent bool

I need to migrate data from one to the other.

So I have only 2 conditions while inserting:

1. I cannot insert the address which has already been inserted into the emp_address for that employee.

2. The is_permanent flag is set to true if no address has been inserted for the employee (i.e. if no single entry is present for the employee set is as true else false)

I cannot seem to get my head around how to I do this.

Answer

Use not exists :

insert into emp_address (address,emp_id,is_permanent)
    select ea.address, e.id, IIF(ea.number IS NOT NULL,0,1)  
      from employees e
      left join dbo.emp_address ea 
        on e.id=ea.emp_id 
     where not exists ( select 0 
                           from dbo.emp_address 
                           where e.id = emp_id 
                             and e.home_address = address )
       and ea.address is not null