如何设置更改Linq为excel Null字符串值？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.OleDb;

class Program
{
    static void Main()
    {
        string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\path\\to\\your\\excel.xlsx;Extended Properties=\"Excel 12.0;HDR=YES;\"";
        using (OleDbConnection connection = new OleDbConnection(connectionString))
        {
            connection.Open();
            string query = "SELECT * FROM [Sheet1$]";
            using (OleDbCommand command = new OleDbCommand(query, connection))
            {
                using (OleDbDataReader reader = command.ExecuteReader())
                {
                    List<string> data = new List<string>();
                    while (reader.Read())
                    {
                        string value = reader.IsDBNull(0) ? "" : reader.GetString(0);
                        data.Add(value);
                    }

                    var result = data.Select(item => item ?? "").ToList();
                    foreach (var item in result)
                    {
                        Console.WriteLine(item);
                    }
                }
            }
        }
    }
}