如何在 C# 中使用 EF 从 MySQL table 获取第一个和最后一个日期？

Question

这是我获取第一次约会的代码。它有效，我可以在 dateTimepicker 中显示日期。

private void ShowButton_Click(object sender, EventArgs e)
{
    String constring = "datasource=;port=3306;username=;password=";

    MySqlConnection connection = new MySqlConnection(constring);

    int n = Convert.ToInt32(textBox1.Text);
    testEntities dc = new testEntities(); 

    var getfirstDate = dc.table.Where(b => b.number == n).First();

    dateTimePicker1.Text =Convert.ToString (getfirstDate.date);
}

但是，当我尝试对最后一个日期做同样的事情时

var getlastDate = dc.table.Where(b => b.number == n).Last();

出现一条错误消息：

LINQ to Entities does not recognize the method 'project.table Lasttable' method, and this method cannot be translated into a store expression.

Answer 1

为什么不使用排序？

var getlastDate = dc.table.Where(b => b.number == n).OrderByDescending(b => b.Date).First();

//alternatively to using Where().First();

var getlastDate = dc.table.First(b => b.number == n).OrderByDescending(b => b.Date)

Answer 2

您可以使用 OrderByDescending() + First():

var lastDate = table.Where(b => b.number == n)
     .OrderByDescending(b => b.Date)
     .First();