LINQ的左连接、右连接、内连接

  

   

    

     

    
    

     

      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,
     
    
   

    

     

    
    

     

                       };
     
    
  
 

  
 
 

文章来源: zzzili.blog.csdn.net，作者：清雨小竹，版权归原作者所有，如需转载，请联系作者。

原文链接：zzzili.blog.csdn.net/article/details/52085424