var dealerDtoList = await db

    .Queryable<Customer>()

    .LeftJoin<User>((a, b) => a.UserGuid == b.Guid,)

    .Where(expable.ToExpression())

    .GroupBy((a, b) => new

    {

        a.Guid,

        userName = b.Name,

        b.AddTime,

    })

    .Select((a, b) => new

    {

        customerGuid = a.Guid,

        userName = b.Name,

        dealerBasicInfoAddTime = c.AddTime,

        daysWithoutOrder = SqlFunc.MappingColumn<bool>(" max(b.AuditTime) is not null ") ?

        SqlFunc.DateDiff(DateType.Day, SqlFunc.AggregateMax(Convert.ToDateTime(b.AuditTime)), DateTime.Now) :

        SqlFunc.MappingColumn<int>("99999")

    })

    .MergeTable()

    .OrderByIF(dealerSign == 1, it => it.dealerBasicInfoAddTime, OrderByType.Desc)

    .OrderByIF(dealerSign == 2, it => it.daysWithoutOrder, OrderByType.Desc)

    .ToPageListAsync(pageIndex, pageSize, allCount);

红色代码为报错的部分，我测试了许多版本，最后一个能用的版本是5.1.4.189，超过这个版本，都会报错