Insert multiple rows from gridview into database

you can use Sql bulk copy for this purpose

private void StartImport()
{
       SqlBulkCopy bulkCopy = new SqlBulkCopy("Server=ServerName;Database=test;Trusted_Connection=True;",
        SqlBulkCopyOptions.TableLock);
    bulkCopy.DestinationTableName = "dest table Name";
 
     DataTable dt = CreateDataTableFromFile();
    bulkCopy.WriteToServer(dt);
       }
 

private DataTable CreateDataTableFromFile()
{
 
       //create a datatable and fill it with the values from the grridview
 
        return the Datatable; 
}