linq 多个left join 和 sql union all -> linq union 方法

 (

  from s in Base_SysMenus

  join r in Base_RoleRights on s.Menu_Id equals r.Menu_Id into temp

  from s_r in temp.DefaultIfEmpty()

 

  join u in Base_UserRoles on s_r.Roles_ID equals u.Roles_ID into temp2

  from t in temp2.DefaultIfEmpty()

  where s.Target=="Iframe" && t.User_ID=="48f3889c-af8d-401f-ada2-c383031af92d" && s.DeleteMark==1

  select new{Menu_Id= s.Menu_Id}

 ).Union(

  from s in Base_SysMenus

  join r in Base_UserGroupRights on s.Menu_Id equals r.Menu_Id into temp

  from s_r in temp.DefaultIfEmpty()

 

  join u in Base_UserInfoUserGroups on s_r.UserGroup_ID equals u.UserGroup_ID into temp2

  from t in temp2.DefaultIfEmpty()

  where s.Target=="Iframe" && t.User_ID=="48f3889c-af8d-401f-ada2-c383031af92d" && s.DeleteMark==1

  select new{Menu_Id= s.Menu_Id}

 ).Union(

  from s in Base_SysMenus

  join r in Base_UserRights on s.Menu_Id equals r.Menu_Id into temp

  from s_r in temp

  where s.Target=="Iframe" && s_r.User_ID=="48f3889c-af8d-401f-ada2-c383031af92d" && s.DeleteMark==1

  select new{Menu_Id= s.Menu_Id}

 )

 

参考资料 ： http://www.cnblogs.com/xlhblogs/archive/2012/01/17/2324478.html