1、左連接：

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??
};

?

如果想實現右連接，就把兩個表換一下位置。

?

2、右連接：

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, ? ? ? ? ?//重點
DepartmentName = dept.Name?
};

?左鏈接或右鏈接，使用DefaultIfEmpty()語法，采用些語法前需要用到into語法

3、內連接：

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,

};

轉載于:https://www.cnblogs.com/DSC1991/p/8705765.html

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