title: System.Data.OracleClient and .Net Core 2: Additional symbol some times?
body: <p>here is how to reproduce it:</p>
  
  <ol>
  <li>Make new console .Net Core 2 project.</li>
  <li>Add System.Data.OracleClient from NuGet.</li>
  <li><p>Change the class Program with this:</p>
  
  <pre><code>class Program  
  {  
      const string testSql = @"  
      SELECT  extension,  
           CASE UPPER (EXTENSION)  
                WHEN 'DOC' THEN 'application/msword'  
                WHEN 'DOCX' THEN 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'  
                WHEN 'XLS' THEN 'application/vnd.ms-excel'  
                WHEN 'XLSX' THEN 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'  
                WHEN 'PPT' THEN 'application/vnd.ms-powerpoint'  
                WHEN 'PPTX' THEN 'application/vnd.openxmlformats-officedocument.presentationml.presentation'  
                WHEN 'EPS' THEN 'application/postscript'  
                WHEN 'GIF' THEN 'image/gif'  
                WHEN 'BMP' THEN 'image/bmp'  
                WHEN 'JPG' THEN 'image/jpeg'  
                WHEN 'MP4' THEN 'video/mp4'  
                WHEN 'PDF' THEN 'application/pdf'  
                WHEN 'PNG' THEN 'image/png'  
                WHEN 'PSD' THEN 'image/vnd.adobe.photoshop'  
                WHEN 'TIF' THEN 'image/tiff'  
                WHEN 'TIFF' THEN 'image/tiff'  
                WHEN 'ZIP' THEN 'application/zip'  
                ELSE 'text/plain'  
             END AS mime_type  
        FROM (  
           select 'bmp' as extension from dual  
           union all  
           select 'jpg' as extension from dual  
           union all  
           select 'tif' as extension from dual  
           union all  
           select 'pdf' as extension from dual  
           union all  
           select 'zip' as extension from dual  
           union all  
           select 'gif' as extension from dual  
           union all  
           select 'txt' as extension from dual  
        )";  
  
      const string _connString = "Data Source = mydatabase; User Id = myuser; Password=mypw;Min Pool Size=1;";  
  
      static void Main(string[] args)  
      {  
          using (var myconn = new OracleConnection(_connString))  
          {  
              myconn.Open();  
              OracleCommand oc = new OracleCommand(testSql, myconn);  
              using (OracleDataReader odr = oc.ExecuteReader(System.Data.CommandBehavior.Default))  
              {  
                  while (odr.Read())  
                  {  
                      var s = odr.GetString(odr.GetOrdinal("MIME_TYPE"));  
                      Console.WriteLine($"Extension: {odr[0]}  Mime type: {odr[1]}");  
                  }  
              }  
              Console.ReadKey();  
          }  
      }  
  }  
  </code></pre></li>
  <li><p>Change the DB, User and Password and start the program.</p></li>
  </ol>
  
  <p>What I get is this:</p>
  
  <pre><code>Extension: bmp  Mime type: image/bmp?
  Extension: jpg  Mime type: image/jpeg?
  Extension: tif  Mime type: image/tiff?
  Extension: pdf  Mime type: application/pdf
  Extension: zip  Mime type: application/zip
  Extension: gif  Mime type: image/gif?
  Extension: txt  Mime type: text/plain?
  </code></pre>
  
  <p>Look at the '?' at the end of some rows.
  The question is: Is this an error on my Oracle Client or is in the System.Data.OracleClient?</p>