各位好.请教个问题

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var Track = from track in datatable.AsEnumerable()
where !track.IsNull("datetime2") || !track.IsNull("datetime1")
group track by new { t1 = track.Field<string>("number") } into TraInfo
select new
{
TraKDDH = TraInfo.First().Field<string>("number"),

MaxExtimsteTime = TraInfo.Max(n => n.Field<DateTime>("datetime1")),

MaxActual = TraInfo.Max(n => n.Field<DateTime>("datetime2"))
};

datatable中，datetime1,datetime2可能为空，然后LINQ就会报 不能将空转换为时间的错，求教各位如何解决

[盼着到1]

引用 楼主 u012480478 的回复:

var Track = from track in datatable.AsEnumerable() where !track.IsNull("datetime2") || !track.IsNull("datetime1") group track by new { t1 = track.Field<string>("number") } into TraInfo select new { TraKDDH = TraInfo.First().Field<string>("number"), MaxExtimsteTime = TraInfo.Max(n => n.Field<DateTime>("datetime1")), MaxActual = TraInfo.Max(n => n.Field<DateTime>("datetime2")) }; datatable中，datetime1,datetime2可能为空，然后LINQ就会报 不能将空转换为时间的错，求教各位如何解决

改过了，还是会报错.. var Track = from track in dt28.AsEnumerable() where track.Field<Object>("YJDGSJ") != DBNull.Value || track.Field<Object>("SJDGSJ") != DBNull.Value group track by new { t1 = track.Field<string>("KDDH") } into TraInfo select new { TraKDDH = TraInfo.First().Field<string>("KDDH"), //最大预计到港时间 MaxExtimsteTime = TraInfo.Max(n => n.Field<DateTime>("YJDGSJ")), //最大实际到港时间 MaxActual = TraInfo.Max(n => n.Field<DateTime>("SJDGSJ")) };

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引用 1 楼 bdmh 的回复:

判断字段为空值用 DBNull.Value

var Track = from track in dt28.AsEnumerable() where track.Field<Object>("YJDGSJ") != DBNull.Value || track.Field<Object>("SJDGSJ") != DBNull.Value group track by new { t1 = track.Field<string>("KDDH") } into TraInfo select new { TraKDDH = TraInfo.First().Field<string>("KDDH"), //最大预计到港时间 MaxExtimsteTime = TraInfo.Max(n => n.Field<DateTime>("YJDGSJ")), //最大实际到港时间 MaxActual = TraInfo.Max(n => n.Field<DateTime>("SJDGSJ")) };改过了，还是会报错，是不是我select new 里写的有问题

[bdmh]

判断字段为空值用 DBNull.Value