max number of columns that excel 2007 supports is 16k
http://visio.mvps.org/Excel_2007.htm

so I have 280, and when read the sheet - the result is 255. My question is
why?

The total number of available columns in Excel 256 (2^8) 16k (2^14)
"dk" wrote:

On Apr 28, 1:47 am, wrote:
hi,

why I still get result 255 columns as I have approximately 280 in my
test1.xlsx
here is the code used

string connectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data
Source=C:\test1.xlsx;Extended Properties=""Excel 12.0;HDR=YES;""";

string strSQL = "SELECT * FROM [test$]";
OleDbConnection excelConnection = new OleDbConnection
(connectionString);

OleDbCommand dbCommand = new OleDbCommand(strSQL,
excelConnection);
OleDbDataAdapter dataAdapter = new OleDbDataAdapter
(dbCommand);

System.Data.DataTable dTable = new System.Data.DataTable
();
dataAdapter.Fill(dTable);
Trace.WriteLine(dTable.Columns.Count.ToString
());


Maximum no. of columns that you can have is 256. What do you mean by
"approximately 280 in my test1.xlsx" ??