Import Excel file data into Sql server using asp.net

First you need to Replace Connection string :

OleDbConnection OleDbcon = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 12.0;");

With this :

If you are use import for .xls then use below one :

OleDbConnection OleDbcon = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path + "; Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"");

If you are use import for .xlsx then use below one :

OleDbConnection OleDbcon = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + "; Extended Properties='Excel 12.0;HDR=YES;IMEX=1;';");

Try this blow one :

try
{
    if (FlUploadcsv.HasFile)
    {
        OleDbConnection OleDbcon;
        OleDbCommand cmd = new OleDbCommand(); ;
        OleDbDataAdapter objAdapter1 = new OleDbDataAdapter();
        DataSet ds = new DataSet();
        DataTable dtExcelData = new DataTable();

        string FileName = FlUploadcsv.FileName;
        string filePath = "C:\\Users\\admin\\Desktop\\Sheet1.xlsx";
        string path = filePath;// string.Concat(Server.MapPath("~/Document/" + FlUploadcsv.FileName));

        FlUploadcsv.PostedFile.SaveAs(path);

        if (Path.GetExtension(path) == ".xls")
        {
            OleDbcon = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path + "; Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"");
        }
        else if (Path.GetExtension(path) == ".xlsx")
        {
            OleDbcon = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + "; Extended Properties='Excel 12.0;HDR=YES;IMEX=1;';");
        }

        OleDbcon.Open();
        cmd.Connection = OleDbcon;
        cmd.CommandType = CommandType.Text;
        cmd.CommandText = "SELECT * FROM [Sheet1$]";
        objAdapter1 = new OleDbDataAdapter(cmd);
        objAdapter1.Fill(ds);
        dtExcelData = ds.Tables[0];

        string consString = "Your Sql Connection string";

        /* You want insert into your sql database table using SqlBulkCopy. */
        using (SqlConnection con = new SqlConnection(consString))
        {
            using (SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(con))
            {
                //Set the database table name
                sqlBulkCopy.DestinationTableName = "SqlDatabase Table name where you want insert data";

                //[OPTIONAL]: Map the Excel columns with that of the database table
                sqlBulkCopy.ColumnMappings.Add(".xls/.xlsx Header column name(Id)", "Your database table column(IndexId)");
                .
                .
                .
                con.Open();
                sqlBulkCopy.WriteToServer(dtExcelData);
                con.Close();
            }
        }
        /* You want insert into your sql database table using SqlBulkCopy. */
    }
}
catch (Exception ex)
{ }

Here is a similar way to do it:

string filename = System.IO.Path.GetFileName(FileUpload1.FileName);
if (FileUpload1.HasFile == true) {
string fp = System.IO.Path.GetDirectoryName(FileUpload1.FileName);
string full = "C:\\Users\\user\\Documents\\" + filename;
TextBox1.Text = full;
//FileUpload1.SaveAs(Server.MapPath("Files/" + filename))
try {
    string connStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=full;Extended Properties=Excel 8.0;HDR=YES;";
    string cmdStr = "Select * from [Sheet1$]";
    using (OleDbConnection oledbconn = new OleDbConnection(connStr)) {
        using (OleDbCommand oledbcmd = new OleDbCommand(cmdStr, oledbconn)) {
            oledbconn.Open();
            OleDbDataAdapter oledbda = new OleDbDataAdapter(oledbcmd);
            DataSet ds = new DataSet();
            oledbda.Fill(ds);
            //save to an SQL Database
            oledbconn.Close();
        }
    }

} catch (Exception ex) {
    TextBox2.Text = ex.ToString();
}
}