Linq查询

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,

                 };