exporting excel datas as it is in excel to sql using c#

It is English, sortof. The words, I understand them well, but what is he trying to tell us? :)

Ah! The eternal question!

There is a straightforward and easy way to do this with an excel library for C#.
Here is how:

using (SqlConnection conn = new SqlConnection("your connection"))
{
conn.Open();
using (SqlBulkCopy bc = new SqlBulkCopy(conn))
{
// Load an Excel file.
ExcelFile ef = ExcelFile.Load("Sample.xlsx");

// Select targeted worksheet.
ExcelWorksheet ws = ef.Worksheets[0];

// Create DataTable options.
var options = new CreateDataTableOptions();
// Set required options, for example:
options.ColumnHeaders = true;

// Create DataTable object.
DataTable dataTable = ws.CreateDataTable(options);

// Execute bulk copy.
bc.WriteToServer(dataTable);
}
}

In short you export an excel data into a DataTable object with C# and then execute an SqlBulkCopy. The only thing you need is to replace the "your connection" in above sample code with your SQL database connection.