正如我在评论中提到的，您遇到的主要问题是您的成员变量是静态的，因此当您设置该值时，它们在所有实例中都会更改.你应该这样改变你的代码:

The main problem you have, as I mentioned in comments is your member variables are static, so when you set the value, they change in all instances. you should change your code this way:

public class Blog
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Message { get; set; }
}

以这种方式填写您的列表，不要忘记添加using System.Linq;:

And fill your list this way, don't forget to add using System.Linq;:

var result = new List<Blog>();
var connection = @"your connection string";
var command = "SELECT * FROM Kristina_Blogs";
var adapter = new System.Data.SqlClient.SqlDataAdapter(command, connection);
var dataTable = new DataTable();

//Get data
adapter.Fill(dataTable);

dataTable.Rows.Cast<DataRow>().ToList()
            .ForEach(row =>
            {
                var b = new Blog();
                b.Id = row.Field<int>("Id");
                b.Title = row.Field<string>("Title");
                b.Message = row.Field<string>("Message");

                result.Add(b);
            });

return result;

注意:

• 当您创建成员时静态，它在该类的所有实例之间共享.
• 在 C# 中，您可以使用 property 获取或设置值，你不需要setX 或setY，当你获取一个属性的值时，get 代码该属性的一部分将执行，当您为属性赋值时，它的 set 部分将执行.你可以这样定义属性:

• When you create a member static, it is shared between all instances of that calss.
• In C# you can use property to get or set values, you don't need to setX or setY, when you get the value of a property, the get code of that property will execute and when you assign a value to a property the set part of it will execute. you can define properties this way:

属性:

private int id;
public int Id
{
    get
    {
        return id;
    }
    set
    {
        id = value;
    }
}

或更简单:

public int Id { get; set; }