sql - Linq to SQL 左外连接不

Question

我有两个表“Employees”和“EmployeesCompanies”，Employees 包含所有员工的列表，employeecompanies 包含与员工关联的所有公司的列表:

Table 1 (Employees)EmployeeID123Table 2 (EmployeesCompanies)EmployeeID    12

I want to return 3 which is the missing record from EmployeesCompanies, here is the linq code I'm using:

var queryOrphanedEmployees = (from a in db.Employees
join b in db.EmployeesCompanies
on a.EmployeeID equals b.EmployeeID
into outer
from c in outer.DefaultIfEmpty()
select new { a.EmployeeID}).ToList();

但是这会返回:

12

这与我想要的完全相反。

Answer 1

如果你已经正确设置了外键，你应该能够做这样的事情

from e in Employees
where !e.EmployeesCompanies.Any()
select e