Question

我的成员表有一个名为Birthdate的可为空的DateTime字段。我需要在接下来的n天内找到生日的成员。我尝试了一些方法，但没有一种方法有效。

1

WITH MYVALUES AS (
SELECT 1 MYVALUE FROM DUAL
UNION ALL SELECT 3 FROM DUAL
UNION ALL SELECT 2 FROM DUAL
UNION ALL SELECT 5 FROM DUAL
UNION ALL SELECT 3 FROM DUAL
UNION ALL SELECT 2 FROM DUAL
UNION ALL SELECT 4 FROM DUAL
)

SELECT 
MYVALUE, 
SUM (MYVALUE) OVER (PARTITION BY NULL ORDER BY NULL ROWS BETWEEN CURRENT ROW AND 4 FOLLOWING) S
FROM MYVALUES

无法将x.BirthDate传递给DateTime构造函数

2

DateTime startDate = DateTime.Now;
DateTime endDate = DateTime.Now.AddDays(n);

GetAll().Where(
    x => x.BirthDate != null 
    && new DateTime(startDate.Year, x.BirthDate.Value.Month, x.BirthDate.Value.Day, 1, 1, 1) >= startDate 
    && new DateTime(endDate.Year, x.BirthDate.Value.Month, x.BirthDate.Value.Day, 1, 1, 1) <= endDate 
    );

抛出识别错误。

你知道有什么工作和简单的方法吗？

Answer 1

linq-to-nhibernate支持DateTime和DateTimeOffset上的一系列属性。您可以看到列表here。 reference documentation有一天也会有专门的Linq部分。（已经提交，尚未发布。）

因此，猜测您的GetAll会产生IQueryable，您可以这样编写查询：

var startDate = DateTime.Now;
var endDate = DateTime.Now.AddDays(n);
if (startDate.Year == endDate.Year)
{
    // Simple case, just compare months and days.
    GetAll().Where(
        x => x.BirthDate.Value.Month >= startDate.Month &&
            x.BirthDate.Value.Day >= startDate.Day &&
            x.BirthDate.Value.Month <= endDate.Month &&
            x.BirthDate.Value.Day <= endDate.Day);
}
else
{
    // Range spanning two distinct years, so matching dates
    // are either lower months and days than endDate, OR
    // greater months and days than startDate. (Cannot have both.)
    GetAll().Where(
        x => x.BirthDate.Value.Month >= startDate.Month &&
            x.BirthDate.Value.Day >= startDate.Day ||
            x.BirthDate.Value.Month <= endDate.Month &&
            x.BirthDate.Value.Day <= endDate.Day);

}

我已经删除了对HasValue的检查：如果查询被转换为SQL，则在这种情况下SQL不需要它。

顺便说一句，它应该与queryover一起使用，我相信它支持相同的DateTime属性。

NHibernate如何获得在n天内过生日的会员

1 个答案: