Question

我正在尝试从所点击的项目的数据库中获取id。我需要做什么来获取列表视图中单击项的ID。它显示为零值以及如何根据数据库中的id获取描述。

namespace javalearningapp_v1 {
    public sealed partial class tutorial: Page {
        string path;
        SQLite.Net.SQLiteConnection conn;
        private List < tutoriallistdb > listOfStudents = new List < tutoriallistdb > ();
        public tutorial() {
            this.InitializeComponent();
            path = Path.Combine(Windows.Storage.ApplicationData.Current.LocalFolder.Path, "java2db.sqlite");
            conn = new SQLite.Net.SQLiteConnection(new SQLite.Net.Platform.WinRT.SQLitePlatformWinRT(), path);
            conn.CreateTable < tutoriallistdb > ();
            Retrieve();
        }
        public class tutoriallistdb {
            [PrimaryKey]
            public Int32 sno {
                get;
                set;
            }
            public string lname {
                get;
                set;
            }
            public string description {
                get;
                set;
            }
        }

        private void Retrieve() {
            var query = conn.Table < tutoriallistdb > ();
            string name = "";

            foreach(var message in query) {
                name = message.lname;
                listOfStudents.Add(new tutoriallistdb {
                    lname = name
                });

            }
            tutoriallist.ItemsSource = listOfStudents;

        }

        private void tutoriallist_ItemClick(object sender, ItemClickEventArgs e) {
            tutoriallistdb item = (tutoriallistdb) e.ClickedItem;
            var desc = conn.Query < tutoriallistdb > ("select description from tutoriallistdb where sno=?", a.sno);
            Frame.Navigate(typeof(tutdesc), desc);
        }
    }
}

Answer 1

var desc = conn.Query＆lt; tutoriallistdb＆gt; （＆＃34;从tutoriallistdb中选择说明，其中sno =？＆＃34;，a.sno）;

问题似乎与您传递的参数类型有关。对于Sql句子，我建议你传递字符串类型参数。

<强>用法

private void tutoriallist_ItemClick(object sender, ItemClickEventArgs e)
{
    tutoriallistdb item = (tutoriallistdb)e.ClickedItem;
    var desc = conn.Query<tutoriallistdb>("select description from tutoriallistdb where sno=?", item.sno.ToString());
    Frame.Navigate(typeof(tutdesc), desc);
}

<强> PS 我在代码中发现了错误的逻辑。

foreach (var message in query)
{
    name = message.lname;
    listOfStudents.Add(new tutoriallistdb { lname = name});
}
tutoriallist.ItemsSource = listOfStudents;

未分配tutoriallist中此项目的sno属性。它是总是零。因此，您只能查询sno为零的同一数据。

修改

foreach (var message in query)
  {
      name = message.lname;
      listOfStudents.Add(new tutoriallistdb { lname = name , sno = message.sno });
  }
  tutoriallist.ItemsSource = listOfStudents;

如何从listview中所选项目的数据库中获取id

1 个答案: