public void UpdateAccountRole(int id, IEnumerable <int> roleIds)
{
var olds = _amsAccessor.Get <AccountRole>(i => i.AccountId == id && !roleIds.Contains(i.RoleId));
_amsAccessor.DeleteRange(olds);
var news = roleIds.Where(i => !_amsAccessor.Get <AccountRole>().Any(j => j.AccountId == id && j.RoleId == i))
.Select(i => new AccountRole {
AccountId = id, RoleId = i
});
_amsAccessor.InsertRange(news);
_amsAccessor.SaveChanges();
}