1.If column names are fixed means you already know column names compare the column names with data base column names.
To do this first fill the data table from excel then you compare with column names.
ConnectionString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=\"Excel 12.0 Xml;HDR=YES;IMEX=1\";", @"C:\file.xlsx");
objConn.Open();
OleDbCommand objCmdSelect = new OleDbCommand("SELECT * FROM ["xlWorksheet"$]", objConn);
OleDbDataAdapter objAdapter1 = new OleDbDataAdapter();
objAdapter1.SelectCommand = objCmdSelect;
DataSet objDataset1 = new DataSet();
objAdapter1.Fill(objDataset1);
objConn.Close();
foreach(DataTable table in objDataset1 .Tables)
{
foreach(DataColumn column in table.Columns)
{
Console.WriteLine(column.ColumnName);
}
}