This step-by-step article describes how to format DateTime and Date values
in the XML that is extracted from an ADO.NETDataSet object.
In ADO.NET, the DateTime and Date values
of DataTable columns are written
in the XSD DateTime and Dateformats
when the DataSet is saved as XML.
The standard XSD DateTime and Date formats
are CCYY-MM-DDThh:mm:ss and CCYY-MM-DD, respectively, because the underlying XSD schema of the DataSet maps
the DateTime and Date columns
of the database to the DateTime and
XSD Date data types. 

如上微软官方原文，日期和时间之间要用T连接，不然不能识别。

安卓和ios开发时都要注意这问题。