C# 从DateTime列中为每天选择最小时间值

有一个表列RecordDateTime：

 20.2.2021 12:54:34
 20.2.2021 13:54:34
 20.2.2021 14:54:34
 20.2.2021 15:54:34
 20.2.2021 16:54:34
 21.2.2021 11:50:00
 21.2.2021 13:54:34
 21.2.2021 14:54:34
 22.2.2021 10:00:00
 22.2.2021 13:54:34
 22.2.2021 14:54:34

我需要接电话

20.2.2021 12:54:34 
21.2.2021 11:50:00 
22.2.2021 10:00:00

并计算平均时间

这是我目前的代码：

    public TimeSpan BeginTime(DateTime startDate, DateTime endDate)
    {
            var mainGridInfo = from w in db.LogModel
                               where w.RecordDateTime.Date >= startDate.Date && w.RecordDateTime.Date <= endDate.Date
                               group w by w.RecordDateTime.Date into test
                               select test.OrderByDescending(cs => cs.RecordDateTime.TimeOfDay).FirstOrDefault();

            var minDatesList = mainGridInfo.Select(s => s.RecordDateTime.TimeOfDay).ToList();

            double doubleAverageTicks = minDatesList.Average(timeSpan => timeSpan.Ticks);
            long longAverageTicks = Convert.ToInt64(doubleAverageTicks);

            return new TimeSpan(longAverageTicks);
    }

转换，或通过插入 调用“AsEnumerable”、“AsAsAsAsyncEnumerable”、“ToList”或 “ToListSync”。寻找 更多信息。”

请尝试以下操作：

            DataTable dt = new DataTable();
            dt.Columns.Add("Date", typeof(DateTime));

            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 12:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 15:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 16:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 11:50:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("22.2.2021 10:00:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("22.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] { DateTime.ParseExact("22.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});

            var days = dt.AsEnumerable().GroupBy(x => x.Field<DateTime>("Date").Date).ToList();
            DateTime[] minDate = days.Select(x => x.Min(y => y.Field<DateTime>("Date"))).ToArray();

请尝试以下操作：

            DataTable dt = new DataTable();
            dt.Columns.Add("Date", typeof(DateTime));

            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 12:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 15:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("20.2.2021 16:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 11:50:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("21.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("22.2.2021 10:00:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] {DateTime.ParseExact("22.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});
            dt.Rows.Add(new object[] { DateTime.ParseExact("22.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture)});

            var days = dt.AsEnumerable().GroupBy(x => x.Field<DateTime>("Date").Date).ToList();
            DateTime[] minDate = days.Select(x => x.Min(y => y.Field<DateTime>("Date"))).ToArray();

假设我们有一些列表日期，我们应该按日期对它们进行分组，并从每个组中提取最小值，如下所示：

var groupedDates = dates.GroupBy(d => d.Date)
               .Select(
                   d => d.OrderByAscending(x => x.Millisecond).FirstOrDefault());

假设我们有一些列表日期，我们应该按日期对它们进行分组，并从每个组中提取最小值，如下所示：

var groupedDates = dates.GroupBy(d => d.Date)
               .Select(
                   d => d.OrderByAscending(x => x.Millisecond).FirstOrDefault());

---

再看看我的变体：

using System;
using System.Collections.Generic;
using System.Linq;

namespace Game
{
    class LogModel
    {
        public DateTime RecordDateTime { get; set; }
    }

    class Program
    {   
        static List<LogModel> _log = new List<LogModel>
        {
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 12:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 15:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 16:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 11:50:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 10:00:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
        };

        static void Main(string[] args)
        {
            var result = _log.GroupBy(x => x.RecordDateTime.Date)
                .Select(x => 
                {
                    var minTime = x.Min(y => y.RecordDateTime.TimeOfDay);

                    return new DateTime(x.Key.Year, x.Key.Month, x.Key.Day, minTime.Hours, minTime.Minutes, minTime.Seconds);
                })
                .ToList();

            result.ForEach(x => Console.WriteLine(x));
        }
    }
}

---

再看看我的变体：

using System;
using System.Collections.Generic;
using System.Linq;

namespace Game
{
    class LogModel
    {
        public DateTime RecordDateTime { get; set; }
    }

    class Program
    {   
        static List<LogModel> _log = new List<LogModel>
        {
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 12:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 15:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("20.2.2021 16:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 11:50:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("21.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 10:00:00", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 13:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
            new LogModel { RecordDateTime = DateTime.ParseExact("22.2.2021 14:54:34", "dd.M.yyyy HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture) },
        };

        static void Main(string[] args)
        {
            var result = _log.GroupBy(x => x.RecordDateTime.Date)
                .Select(x => 
                {
                    var minTime = x.Min(y => y.RecordDateTime.TimeOfDay);

                    return new DateTime(x.Key.Year, x.Key.Month, x.Key.Day, minTime.Hours, minTime.Minutes, minTime.Seconds);
                })
                .ToList();

            result.ForEach(x => Console.WriteLine(x));
        }
    }
}

---

什么是您的DBMS，看起来像SQLite？您使用的是哪种Linq提供程序？是20.2.2021 12:54:34一列还是两列？@Charlieface它是SQLite@IvanKhorin我使用的是一列RecordDateTime。不涉及其他列。@mrwd，如果RecordDateTime是一个类，请提供它的定义。日期是字符串吗？一天中的时间是一个问题吗？你们的数据库管理系统是什么，看起来像SQLite？您使用的是哪种Linq提供程序？是20.2.2021 12:54:34一列还是两列？@Charlieface它是SQLite@IvanKhorin我使用的是一列RecordDateTime。不涉及其他列。@mrwd，如果RecordDateTime是一个类，请提供它的定义。日期是字符串吗？TimeOfDay是一个stirng吗？尽量避免使用DataTable的概念，这是一个噩梦。列出minTime=db.LogModel.AsEnumerable.GroupByx=>x.RecordDateTime.Date.Selectx=>x.Miny=>y.RecordDateTime.TimeOfDay.ToList；这似乎对我的情况有效。经过一些调查，我认为这里的重点是使用。可计算的。我应该提到，我正在使用EFCore从数据库中查询。直接查询和不添加数据一样似乎有一些限制。可计算的一切似乎都在工作。尽量避免使用数据表概念，这是一场噩梦。列出minTime=db.LogModel.AsEnumerable.GroupByx=>x.RecordDateTime.Date.Selectx=>x.Miny=>y.RecordDateTime.TimeOfDay.ToList；这似乎对我的情况有效。经过一些调查，我认为这里的重点是使用。可计算的。我应该提到，我正在使用EFCore从数据库中查询。看起来直接查询和不添加都有一些限制。可计算的一切似乎都在运行。