如何从数据库中获取即将到来的生日？答案

【问题标题】：How to Fetch Upcoming Birthdays from Database?如何从数据库中获取即将到来的生日？
【发布时间】：2016-02-22 16:40:55
【问题描述】：

我有一个数据库，我想从中获取未来 15 天内生日的人的列表。我使用 ASP.NET C# 和 MS-Access 作为数据库。我用谷歌搜索了很多，但找不到正确的解释。我正在使用

select name,category,dob 
from family_details 
where Month(dob) >= Month(NOW()) and Day(dob) > Day(Now()) 
order by dob desc

这个查询，它给出了从今天开始的当前月份的生日列表。我想要的结果是即将到来的 15 天生日（比如说）的列表......

【问题讨论】：

SO Post 认为它回答了你的问题
SQL Select Upcoming Birthdays的可能重复
它不工作...
@Filburt 为什么使用 SQL Server 回答 MS Access SQL 问题？
@Filburt 它不是那个问题的重复。

标签： c# sql asp.net .net ms-access

【解决方案1】：

试试这个。 Add 在current date 中的 15 天并从中获取 month。

select name,category,dob 
from family_details 
where Month(dob) in(Month(NOW()),Month(DateAdd(d,15,NOW()))) 
order by dob desc

Month 可以更改为next 15 days，因此您还需要获得month。在这里您将获得two values 一个用于current month，另一个是在当前日期添加15 days 之后，如果month已更改，您也将获得 month 的值。

【讨论】：

【解决方案2】：

您可能需要一个辅助函数来为跳跃者（2 月 29 日出生的人）设置正确的函数。诀窍是使用AddYears，它不会在闰年失败。

可以创建为DateTime的扩展方法：

/// <summary>
/// Calculates the next annual day of this instance of System.DateTime relative to today.
/// <para>Calculates correctly Feb. 28th as an annual day in common years for event dates of Feb. 29th.</para>
/// <para>If next annual day should be later than 9999-12-31, the annual day of year 9999 is returned.</para>
/// </summary>
/// <param name="eventDate">The date of the event.</param>
/// <returns>The date of the upcoming annual day.</returns>
public static DateTime NextAnnualDay(this DateTime eventDate)
{
    return NextAnnualDay(eventDate, DateTime.Today);
}

/// <summary>
/// Calculates the next annual day of this instance of System.DateTime relative to a future date.
/// <para>Calculates correctly Feb. 28th as an annual day in common years for event dates of Feb. 29th.</para>
/// <para>If futureDate is earlier than this instance, the value of this instance is returned.</para>
/// <para>If next annual day should be later than 9999-12-31, the annual day of year 9999 is returned.</para>
/// </summary>
/// <param name="eventDate">The date of the event.</param>
/// <param name="futureDate">The date from which to find the next annual day of this instance.</param>
/// <returns>The date of the upcoming annual day.</returns>
public static DateTime NextAnnualDay(this DateTime eventDate, DateTime futureDate)
{
    DateTime nextDate = eventDate;
    if (DateTime.MaxValue.Year - eventDate.Year == 0)
    {
        // No later next annual day can be calculated.
    }
    else
    {
        int years = futureDate.Year - eventDate.Year;
        if (years < 0)
        {
            // Don't calculate a hypothetical next annual day.
        }
        else
        {
            nextDate = eventDate.AddYears(years);
            if (nextDate.Subtract(futureDate).Days <= 0)
            {
                if (DateTime.MaxValue.Year - nextDate.Year == 0)
                {
                    // No later next annual day can be calculated.
                }
                else
                {
                    nextDate = eventDate.AddYears(years + 1);
                }
            }
        }
    }
    return nextDate;
}

然后这样走（伪SQL）：

select name, category, dob 
from family_details 
where dob.NextAnnualDay() between today and today.AddDays(15) 
order by dob desc

使用 Linq 完成或转换为参数化 SQL。

【讨论】：