Fluent NHibernate join tables in mapping not using primary key -

i'm trying create 1 entity 2 tables related not primary key

tables:

create table [employees](     [ssn] [nvarchar](9) null,     [active] [bit] null,         [employee_id] [int] identity(1,1) not null  )   create table [sam_employees](     [ssn] [nvarchar](9) null,     [first_name] [nvarchar](50) null,     [last_name] [nvarchar](50) null,     [skill] [nvarchar](50) null,     .... ) 

sql generate:

select this_.employee_id  employee1_0_0_,        this_.ssn          ssn0_0_,        this_.active       active0_0_,        this_1_.first_name first2_1_0_,        this_1_.last_name  last3_1_0_,        this_1_.skill      skill1_0_   employees this_        inner join sam_employees this_1_          on this_.ssn = this_1_.ssn  this_.active = 1 

my current mapping:

public class employeemap : classmap<employee> {     public employeemap()     {         table("employees");         id(x => x.id, "employee_id");         map(x => x.ssn, "ssn");         map(x => x.isactive, "active");          join("sam_employees", mm =>                                   {                                                                                 mm.keycolumn("ssn");                                       mm.map(xx => xx.firstname, "first_name");                                       mm.map(xx => xx.lastname, "last_name");                                       mm.map(xx => xx.skill, "skill");                                   });                 } } 

but mapping have such join condition on this_.employee_id = this_1_.ssn

i know question asked before didn't find answer it, workaround use view in database side instead of tables.

you can try mapping sam_employees entity , use references mapping join type fetch.