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。