内部联接仅返回与两个表匹配或存在的记录或行。我们还可以根据以下条件申请加入多个表。如果我们需要在多个条件下申请加入,请使用匿名类型。
在下面的示例中,我们编写了2种可用于加入Linq的方法。
class Program{ static void Main(string[] args){ var result = Employee.GetAllEmployees().Join(Department.GetAllDepartments(), e => e.DepartmentID, d => d.ID, (employee, department) => new{ EmployeeName = employee.Name, DepartmentName = department.Name }); foreach (var employee in result){ Console.WriteLine(employee.EmployeeName + "\t" + employee.DepartmentName); } var result1 = from e in Employee.GetAllEmployees() join d in Department.GetAllDepartments() on e.DepartmentID equals d.ID select new{ EmployeeName = e.Name, DepartmentName = d.Name }; foreach (var employee in result1){ Console.WriteLine(employee.EmployeeName + "\t" + employee.DepartmentName); } Console.ReadLine(); } } public class Employee{ public int ID { get; set; } public string Name { get; set; } public int DepartmentID { get; set; } public static List<Employee> GetAllEmployees(){ return new List<Employee>(){ new Employee { ID = 1, Name = "A", DepartmentID = 1 }, new Employee { ID = 2, Name = "B", DepartmentID = 2 }, new Employee { ID = 3, Name = "B", DepartmentID = 1 }, new Employee { ID = 4, Name = "V", DepartmentID = 1 }, new Employee { ID = 5, Name = "F", DepartmentID = 2 }, new Employee { ID = 6, Name = "R", DepartmentID = 2 }, new Employee { ID = 7, Name = "TT", DepartmentID = 1 }, new Employee { ID = 8, Name = "YY", DepartmentID = 1 }, new Employee { ID = 9, Name = "WW", DepartmentID = 2 }, new Employee { ID = 10, Name = "QQ"} }; } } public class Department{ public int ID { get; set; } public string Name { get; set; } public static List<Department> GetAllDepartments(){ return new List<Department>(){ new Department { ID = 1, Name = "IT"}, new Department { ID = 2, Name = "HR"}, new Department { ID = 3, Name = "Contract"}, }; } }
输出结果
A IT B HR B IT V IT F HR R HR TT IT YY IT WW HR A IT B HR B IT V IT F HR R HR TT IT YY IT WW HR