C#中Microsoft.ACE.OLEDB.12.0 驱动读取excel，会读取前8行来判定每列的数据类型，假如没有超过255个字符，那么会被设置为nvarchar(255),从第9行开始，超过255字符会被自动截断！
推荐使用第三方库：
ExcelDataReader
ExcelDataReader
Important note on .NET Core
By default, ExcelDataReader throws a NotSupportedException "No data is available for encoding 1252." on .NET Core.
To fix, add a dependency to the package System.Text.Encoding.CodePages and then add code to register the code page provider during application initialization (f.ex in Startup.cs):
By default, ExcelDataReader throws a NotSupportedException "No data is available for encoding 1252." on .NET Core.
To fix, add a dependency to the package System.Text.Encoding.CodePages and then add code to register the code page provider during application initialization (f.ex in Startup.cs):
System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);
This is required to parse strings in binary BIFF2-5 Excel documents encoded with DOS-era code pages. These encodings are registered by default in the full .NET Framework, but not on .NET Core.