exception when executing sql command using sqlite in c# on windows phone - sqlite

Question

my code is like the follow:
SqliteConnection db = new SqliteConnection("uri=file:zongheng.db");db.Open();
SqliteCommand cmd = db.CreateCommand();
cmd.CommandText = "update chapters set status = 0 where bookid=" + bookid + " and chapterid = " + reading_chapter + ";";
cmd.ExecuteNonQuery();
cmd.Dispose();
db.Close();
db.Dispose();
db.Open();
cmd = db.CreateCommand();
cmd.CommandText = ("select max(chapterid), status from chapters where status > 0 and bookid = "+bookid +";");
SqliteDataReader dr = cmd.ExecuteReader(); //exception thrown from here
calling stack is like this:
Community.CsharpSqlite.SQLiteClient.SqliteSyntaxException was unhandled
Message=unable to open database file
StackTrace:
at Community.CsharpSqlite.SQLiteClient.SqliteCommand.GetNextStatement(String pzStart, String& pzTail, Vdbe& pStmt)
at Community.CsharpSqlite.SQLiteClient.SqliteCommand.ExecuteReader(CommandBehavior behavior, Boolean want_results, Int32& rows_affected)
at Community.CsharpSqlite.SQLiteClient.SqliteCommand.ExecuteReader(CommandBehavior behavior)
at Community.CsharpSqlite.SQLiteClient.SqliteCommand.ExecuteReader()
at ZonghengReader.Content.OnNavigatedTo(NavigationEventArgs e)
at Microsoft.Phone.Controls.PhoneApplicationPage.InternalOnNavigatedTo(NavigationEventArgs e)
at System.Windows.Navigation.NavigationService.RaiseNavigated(Object content, Uri uri, NavigationMode mode, Boolean isNavigationInitiator, PhoneApplicationPage existingContentPage, PhoneApplicationPage newContentPage)
at System.Windows.Navigation.NavigationService.CompleteNavigation(DependencyObject content, NavigationMode mode)
at System.Windows.Navigation.NavigationService.ContentLoader_BeginLoad_Callback(IAsyncResult result)
at System.Windows.Navigation.PageResourceContentLoader.BeginLoad_OnUIThread(AsyncCallback userCallback, PageResourceContentLoaderAsyncResult result)
at System.Windows.Navigation.PageResourceContentLoader.<>c__DisplayClass4.<BeginLoad>b__0(Object args)
at System.Reflection.RuntimeMethodInfo.InternalInvoke(RuntimeMethodInfo rtmi, Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
at System.Delegate.DynamicInvokeOne(Object[] args)
at System.MulticastDelegate.DynamicInvokeImpl(Object[] args)
at System.Delegate.DynamicInvoke(Object[] args)
at System.Windows.Threading.DispatcherOperation.Invoke()
at System.Windows.Threading.Dispatcher.Dispatch(DispatcherPriority priority)
at System.Windows.Threading.Dispatcher.OnInvoke(Object context)
at System.Windows.Hosting.CallbackCookie.Invoke(Object[] args)
at System.Windows.Hosting.DelegateWrapper.InternalInvoke(Object[] args)
at System.Windows.RuntimeHost.ManagedHost.InvokeDelegate(IntPtr pHandle, Int32 nParamCount, ScriptParam[] pParams, ScriptParam& pResult)
how can i do different queries within the same connection? any advice? or any documentation? any advice would be highly appreciated.

Answer 1

I don't know if this question is answered yet but... in your code sample you dispose of the object:
...
db.Dispose();
db.Open();
...
I honestly think that's your problem in the current context. just remove the Dispose() call on the database connection object and I think you should be fine. Once you are really done with the object you can Dispose() it.