在linq中按llblgen分组

private IEnumerable<IGrouping<AccountEntity,AxsEntity>> GetAxsEntitiesForInvoicing(IDataAccessAdapter adapter)
{
    var metaData = new LinqMetaData(adapter);
    var query = from axsEntity in metaData.Axs
                join accountEntity in metaData.Account on axsEntity.AccountId equals accountEntity.AccountId
                where
                        (axsEntity.DateDeleted.HasValue? axsEntity.DateDeleted.Value<DateTime.Now:true) &&
                        (axsEntity.DateEnd == null || axsEntity.DateEnd > axsEntity.DateRenewal) &&
                        axsEntity.DateRenewal < RenewalDate // NONE INCLUSIVE DATE
                        group axsEntity by accountEntity into axsCol
                select axsCol;
    return query;

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