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;
                    });