Linq左关联 右关联 内关联

1、左连接：

var LeftJoin = from emp in ListOfEmployees
join dept in ListOfDepartment
on emp.DeptID equals dept.ID into JoinedEmpDept
from dept in JoinedEmpDept.DefaultIfEmpty()
select
new

{
EmployeeName = emp.Name,
DepartmentName = dept != null ? dept.Name :
null

};

 

2、右连接：

var RightJoin = from dept in
ListOfDepartment
join employee in ListOfEmployees
on dept.ID equals employee.DeptID into joinDeptEmp
from employee in joinDeptEmp.DefaultIfEmpty()
select
new

{
EmployeeName = employee != null ? employee.Name : null,
DepartmentName = dept.Name
};

 

3、内连接：

 var query = from t in
entitiy.TB_GCGL_ADA_USER
                
join p in entitiy.TB_GCGL_ZY_ZYK
                
on t.ETPRS_CODE equals p.ETPRS_CODE

                
select new TB_USER_ZYK
                
{
                   
USER_ID = t.USER_ID,
                   
USER_NAME = t.USER_NAME,
                   
USER_PASSWORD = t.USER_PASSWORD,

                
};