Android Azure删除所有行
本文关键字:删除 Azure Android | 更新日期: 2023-09-27 17:54:55
我正在构建一个Android应用程序与Azure数据库(在Xamarin),使用Azure移动服务。我想清除一个表的记录。
虽然有一张桌子。RemoveAsync',我不知道如何选择所有的行。
是用'Select'还是'Where'?我很感激你的帮助。
//Mobile Service Client reference
private MobileServiceClient client;
//Mobile Service sync table used to access data
private IMobileServiceSyncTable<Mashlim> mashlimTable;
const string applicationURL = @"http://blahblah.azurewebsites.net/";
public override async void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
CurrentPlatform.Init();
// Create the Mobile Service Client instance, using the provided
// Mobile Service URL
client = new MobileServiceClient(applicationURL);
await InitLocalStoreAsync();
// Get the Mobile Service sync table instance to use
mashlimTable = client.GetSyncTable<Mashlim>();
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
var view = inflater.Inflate(Resource.Layout.ShabbatMinyan, container, false);
….
OnRefreshItemsSelected();
return view;
}
private async Task InitLocalStoreAsync()
{
// new code to initialize the SQLite store
string path = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), localDbFilename);
if (!File.Exists(path))
{
File.Create(path).Dispose();
}
var store = new MobileServiceSQLiteStore(path);
store.DefineTable<Mashlim>();
// Uses the default conflict handler, which fails on conflict
// To use a different conflict handler, pass a parameter to InitializeAsync. For more details, see http://go.microsoft.com/fwlink/?LinkId=521416
await client.SyncContext.InitializeAsync(store);
}
private async Task SyncAsync()
{
try
{
await client.SyncContext.PushAsync();
await mashlimTable.PullAsync("allMashlims", mashlimTable.CreateQuery()); // query ID is used for incremental sync
}
catch (Java.Net.MalformedURLException)
{
CreateAndShowDialog(new Exception("There was an error creating the Mobile Service. Verify the URL"), "Error");
}
catch (Exception e)
{
CreateAndShowDialog(e, "Error");
}
}
// Called when the refresh menu option is selected
private async void OnRefreshItemsSelected()
{
await SyncAsync(); // get changes from the mobile service
await RefreshItemsFromTableAsync(); // refresh view using local database
}
//Refresh the list with the items in the local database
private async Task RefreshItemsFromTableAsync()
{
try
{
// Get the items that were marked as mashlim and add them to list
var list = await mashlimTable.Where(item => item.IsMashlim == true).ToListAsync();
mashlimim = 0;
foreach (Mashlim current in list)
mashlimim++;
mashlimimNumText.Text = mashlimim.ToString();
}
catch (Exception e)
{
CreateAndShowDialog(e, "Error");
}
}
[Java.Interop.Export()]
public async void AddItem()
{
if (client == null)
{
return;
}
if(Settings.MashlimId==string.Empty)
{
// Create a new item
item = new Mashlim
{
Name = nameText.Text,
PhoneNumber = phoneText.Text,
IsMashlim = true
};
try
{
await mashlimTable.InsertAsync(item); // insert the new item into the local database
await SyncAsync(); // send changes to the mobile service
await RefreshItemsFromTableAsync();
Settings.MashlimId = item.Id;
Settings.MashlimName = item.Name;
Settings.IsMashlim = true;
Settings.MashlimPhone = item.PhoneNumber;
}
catch (Exception e)
{
CreateAndShowDialog(e, "Error");
}
}
else
{
Settings.IsMashlim = true;
item = new Mashlim
{
Id = Settings.MashlimId,
Name = Settings.MashlimName,
IsMashlim = Settings.IsMashlim,
PhoneNumber = Settings.MashlimPhone
};
try
{
await mashlimTable.UpdateAsync(item); // insert the new item into the local database
await SyncAsync(); // send changes to the mobile service
await RefreshItemsFromTableAsync();
mashlim = true;
}
catch (Exception e)
{
CreateAndShowDialog(e, "Error");
}
}
}
}
}
谢谢。
在客户端SDK中,您不能在本地SQLite存储上运行任意SQL语句。所以,你必须选择所有的行,然后循环删除它们。(使用ToListAsync将所有内容加载到内存时要小心,因为这可能会耗尽设备上的内存。)注意,如果您有X行,这将导致X个服务器请求,这可能非常慢。关于如何在客户端执行请求,请参阅本文:如何:在移动应用程序中删除数据。
如果您想要删除符合特定条件的所有行,您最好在服务器上编写自定义API,并通过调用API让客户端只发送一个请求。在服务器端,您可以使用SQL或LINQ,这取决于您使用的是。net还是Node.js。
例如,使用。net后端,您可以使用如何:定义自定义API控制器来创建自定义API。
在你的一个控制器方法中,你会有以下代码:
using (var context = new YourContext())
{
context.ExecuteStoreCommand("DELETE FROM YOURTABLE WHERE Condition = value");
}