Question

我想问一下如何在Entity Framework中编写一个复杂的DateTime查询，如下所示：

我在服务中使用此代码：

Func<DateTime, DateTime> calculate24HoursLater = (date) =>
{
    if (date.DayOfWeek == DayOfWeek.Friday)
        return date.AddDays(3);

    if (date.DayOfWeek == DayOfWeek.Saturday)
        return date.AddDays(3).Date;

    if (date.DayOfWeek == DayOfWeek.Sunday)
        return date.AddDays(2).Date;

    return date.AddDays(1);
};

var unactionedEnquiries = 
    dataContext.ContactedBrokerEnquiries
        .Include("ContactedBrokers")
        .Where(
            x => x.ContactedBrokers.All(c => c.Status == (byte)LeadStatus.Rejected) || 
                x.ContactedBrokers.Any(c => c.Status == (byte)LeadStatus.New && calculate24HoursLater(c.CreatedDate) < DateTime.Now)
        ).OrderByDescending(c => c.CreatedDate);

结果unactionedEnquiries，我希望它应该是IQueryable。这意味着SQL服务器在我的下一个语句

之前不会执行

然而，我在calculate24HoursLater(c.CreatedDate) < DateTime.Now)上获得例外此语句无法转换为SQL语句。我知道原因，但我不知道如何在rule查询

中写Entity Framework

重要提示：我不希望将所有数据推入RAM，然后使用该条件进行过滤。理想情况下，它应该在SQL-Server

请告诉我如何在SQL-EF语句中编写它们？

Answer 1

您可能希望查看可能使用可用于在LINQ查询中执行日期操作的SQLFunctions方法

示例（未经测试）尝试使用以下内容替换您的Func定义：

Func<DateTime, DateTime> calculate24HoursLater = (date) =>
{
    if (date.DayOfWeek == DayOfWeek.Friday)
        return SqlFunctions.DateAdd("day", 3, date).Value;

    if (date.DayOfWeek == DayOfWeek.Saturday)
        return SqlFunctions.DateAdd("day", 3, date).Value;

    if (date.DayOfWeek == DayOfWeek.Sunday)
        return SqlFunctions.DateAdd("day", 2, date).Value;

    return SqlFunctions.DateAdd("day", 1, date).Value;
};

Answer 2

正如我看到here @ andrew的天才回答，你可以这样做：

var calcDate = DateTime.Now.AddHours(-24);

var unactionedEnquiries = 
    dataContext.ContactedBrokerEnquiries
        .Include("ContactedBrokers")
        .Where(
            x => x.ContactedBrokers.All(c => c.Status == (byte)LeadStatus.Rejected) || 
                x.ContactedBrokers.Any(c => c.Status == (byte)LeadStatus.New && c.CreatedDate < calcDate)
        ).OrderByDescending(c => c.CreatedDate);

实体框架中的复杂DateTime查询

2 个答案: