Fluent nhibernate 如何为此sql语句编写nhibernate查询

如何为下面的SQL查询语句编写流畅的nhibernate查询：

select iseat.companynr, mdata.Employeenr from IDepartment as iseat inner join 
Employee as i on i.pkey = iseat.employeefk 
inner join employeedata as edata on edata.employeefk = i.pkey

我已经创建了类

IDepartment

、

Employee

和

Employeedata

，还创建了一个类

companyn2employeenmap

，其中包含两个属性

CompanyNr

和

EmployeeNr

查询需要将companynr列表作为参数，并返回会话中emp中的

CompanyNr2EmployeeNrMap

var query=列表。query（）
var query = from emp in session.Query<Employee>()
            from department in emp.Departments
            select new CompanyNr2EmployeeNrMap
            {
                CompanyNr = department.CompanyNr,
                EmployeeNr = emp.Data.EmployeeNr
            };

return query.ToList();

来自emp部门中的部门
选择新公司R2EmployeenRMAP
{
CompanyNr=department.CompanyNr，
EmployeeNr=emp.Data.EmployeeNr
};
返回query.ToList（）；