Ado.Net Entity Framework 批量删除、判断存在

批量删除：

        public int DeleteAllRoles_PermissionsByRolesId(string rolesId)

        {

            return entities.ExecuteStoreCommand("delete from Roles_Permissions where RolesId = @RolesId", new SqlParameter("@RolesId", rolesId));

        }

判断是否存在：

tmpNd.Checked = roles_PermissionsList.Exists(p=> p.RolesId == hfRolesId.Value && p.PermissionsId == row.PermissionsId);

把委托展开：

                    tmpNd.Checked = roles_PermissionsList.Exists(

                    delegate(Roles_Permissions s1)

                    {

                        if (s1.RolesId == hfRolesId.Value && s1.PermissionsId == row.PermissionsId )

                            return true;

                        else

                            return false;

                    });