No need to worry about only oledb..there is a lot of other method are used to upload .xlsx files(import).
Here is the header:
using ClosedXML.Excel;
Install ClosedXML.Excel
dll from nuget.
Here is the code:
string filePath = Server.MapPath("~/Content/MailMarketing/") + Path.GetFileName(flexcel.PostedFile.FileName);
flexcel.SaveAs(filePath);
//Open the Excel file using ClosedXML.
using (XLWorkbook workBook = new XLWorkbook(filePath))
{
//Read the first Sheet from Excel file.
IXLWorksheet workSheet = workBook.Worksheet(1);
//Create a new DataTable.
DataTable dt = new DataTable();
//Loop through the Worksheet rows.
bool firstRow = true;
foreach (IXLRow row in workSheet.Rows())
{
//Use the first row to add columns to DataTable.
if (firstRow)
{
foreach (IXLCell cell in row.Cells())
{
dt.Columns.Add(cell.Value.ToString());
}
firstRow = false;
}
else
{
//Add rows to DataTable.
dt.Rows.Add();
int i = 0;
foreach (IXLCell cell in row.Cells())
{
dt.Rows[dt.Rows.Count - 1][i] = cell.Value.ToString();
i++;
}
}