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• WPF animation/UI features performance and benchmarking

  - by Rich

  I'm working on a relatively small proof-of-concept for some line of business stuff with some fancy WPF UI work. Without even going too crazy, I'm already seeing some really poor performance when using a lot of the features that I thought were the main reason to consider WPF for UI building in the first place. I asked a question on here about why my animation was being stalled the first time it was run, and at the end what I found was that a very simple UserControl was taking almost half a second just to build its visual tree. I was able to get a work around to the symptom, but the fact that it takes that long to initialize a simple control really bothers me. Now, I'm testing my animation with and without the DropShadowEffect, and the result is night and day. A subtle drop shadow makes my control look so much nicer, but it completely ruins the smoothness of the animation. Let me not even start with the font rendering either. The calculation of my animations when the control has a bunch of gradient brushes and a drop shadow make the text blurry for about a full second and then slowly come into focus. So, I guess my question is if there are known studies, blog posts, or articles detailing which features are a hazard in the current version of WPF for business critical applications. Are things like Effects (ie. DropShadowEffect), gradient brushes, key frame animations, etc going to have too much of a negative effect on render quality (or maybe the combinations of these things)? Is the final version of WPF 4.0 going to correct some of these issues? I've read that VS2010 beta has some of these same issues and that they are supposed to be resolved by final release. Is that because of improvements to WPF itself or because half of the application will be rebuilt with the previous technology?

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• Sync Vs. Async Sockets Performance in .NET

  - by Michael Covelli

  Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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• Compiler optimization causing the performance to slow down

  - by aJ

  I have one strange problem. I have following piece of code: template<clss index, class policy> inline int CBase<index,policy>::func(const A& test_in, int* srcPtr ,int* dstPtr) { int width = test_in.width(); int height = test_in.height(); double d = 0.0; //here is the problem for(int y = 0; y < height; y++) { //Pointer initializations //multiplication involving y //ex: int z = someBigNumber*y + someOtherBigNumber; for(int x = 0; x < width; x++) { //multiplication involving x //ex: int z = someBigNumber*x + someOtherBigNumber; if(soemCondition) { // floating point calculations } *dstPtr++ = array[*srcPtr++]; } } } The inner loop gets executed nearly 200,000 times and the entire function takes 100 ms for completion. ( profiled using AQTimer) I found an unused variable double d = 0.0; outside the outer loop and removed the same. After this change, suddenly the method is taking 500ms for the same number of executions. ( 5 times slower). This behavior is reproducible in different machines with different processor types. (Core2, dualcore processors). I am using VC6 compiler with optimization level O2. Follwing are the other compiler options used : -MD -O2 -Z7 -GR -GX -G5 -X -GF -EHa I suspected compiler optimizations and removed the compiler optimization /O2. After that function became normal and it is taking 100ms as old code. Could anyone throw some light on this strange behavior? Why compiler optimization should slow down performance when I remove unused variable ? Note: The assembly code (before and after the change) looked same.

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• Average performance of binary search algorithm?

  - by Passionate Learner

  http://en.wikipedia.org/wiki/Binary_search_algorithm#Average_performance BinarySearch(int A[], int value, int low, int high) { int mid; if (high < low) return -1; mid = (low + high) / 2; if (A[mid] > value) return BinarySearch(A, value, low, mid-1); else if (A[mid] < value) return BinarySearch(A, value, mid+1, high); else return mid; } If the integer I'm trying to find is always in the array, can anyone help me write a program that can calculate the average performance of binary search algorithm? I know I can do this by actually running the program and counting the number of calls, but what I'm trying to do here is to do it without calling the function. I'm not asking for a time complexity, I'm trying to calculate the average number of calls. For example, the average number of calls to find a integer in A[2], it would be 1.67 (5/3).

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• PHP database simulation

  - by Emdiesse

  I have a PHP script that works by calling items from a database based upon the time they were placed in there and it deletes them if they are older than 5 minutes. Basically, I want to now simulate what would happen if this database was being updated regularly. So I was considering sticking in some code that loads an XML file then goes through and parses that into the database based upon the time data located within a node of the xml data... but the problem there is I want it to continually loop through an enter this data so it'll never actually run the other processes So I was thinking of having another PHP script do that that could do this independantly of the php script that is going to display this data... In theory: I am looking to have a button that I can press and it will then run some php code to load up an XML file from a directory on my web server and then iterate though the data sending the data, to a database, based upon the time within a node in the PHP script and when the script was first called So back to my page that displayed the data... if I continually hit refresh it will contain different results each time because data is being added by the other process and this php script removes the older data when it is refreshed Any information on this? Is there a way I can silently, and safely, run a php script without it being loaded into a browser... like a thread!?

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• Database version is zero on initial install

  - by mahesh

  I have released an app (World Time) with initial database. Now i want to update the app with a database upgrade. I have put in the upgrade code in OnUpgrade() and checking for the newVersion. But it was not being called in my local testing... So i put in the debug statement to get the database version and it is zero . Any idea why it is not being versioned ? Following is the code to copy the database from my Assets folder ... InputStream myInput = myContext.getAssets().open(DB_NAME); // Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))>0){ myOutput.write(buffer, 0, length); } //Close the streams myOutput.flush(); myOutput.close(); myInput.close(); -- Mahesh http://android.maheshdixit.com

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• performance of large number calculations in python (python 2.7.3 and .net 4.0)

  - by g36

  There is a lot of general questions about python performance in comparison to other languages. I've got more specific example: There are two simple functions wrote in python an c#, both checking if int number is prime. python: import time def is_prime(n): num =n/2 while num >1: if n % num ==0: return 0 num-=1 return 1 start = time.clock() probably_prime = is_prime(2147483629) elapsed = (time.clock() - start) print 'time : '+str(elapsed) and C#: using System.Diagnostics; public static bool IsPrime(int n) { int num = n/2; while(num >1) { if(n%num ==0) { return false; } num-=1; } return true; } Stopwatch sw = new Stopwatch(); sw.Start(); bool result = Functions.IsPrime(2147483629); sw.Stop(); Console.WriteLine("time: {0}", sw.Elapsed); And times ( which are surprise for me as a begginer in python:)): Python: 121s; c#: 6s Could You explain where does this big diffrence come from ?

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• Updating MS Access Database from Datagridview

  - by Peter Roche

  I am trying to update an ms access database from a datagridview. The datagridview is populated on a button click and the database is updated when any cell is modified. The code example I have been using populates on form load and uses the cellendedit event. private OleDbConnection connection = null; private OleDbDataAdapter dataadapter = null; private DataSet ds = null; private void Form2_Load(object sender, EventArgs e) { string connetionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='C:\\Users\\Peter\\Documents\\Visual Studio 2010\\Projects\\StockIT\\StockIT\\bin\\Debug\\StockManagement.accdb';Persist Security Info=True;Jet OLEDB:Database Password="; string sql = "SELECT * FROM StockCount"; connection = new OleDbConnection(connetionString); dataadapter = new OleDbDataAdapter(sql, connection); ds = new DataSet(); connection.Open(); dataadapter.Fill(ds, "Stock"); connection.Close(); dataGridView1.DataSource = ds; dataGridView1.DataMember = "Stock"; } private void addUpadateButton_Click(object sender, EventArgs e) { } private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e) { try { dataadapter.Update(ds,"Stock"); } catch (Exception exceptionObj) { MessageBox.Show(exceptionObj.Message.ToString()); } } The error I receive is Update requires a valid UpdateCommand when passed DataRow collection with modified rows. I'm not sure where this command needs to go and how to reference the cell to update the value in the database.

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• Android ExpandableListView From Database

  - by SterAllures

  I want to create a two level ExpandableListView from a local database. The group level I want to get the names from the database Category table category_id | name ------------------- 1 | NameOfCategory the children level I want to get the names from the List table list_id | name | foreign_category_id -------------------------------- 1 | Listname | 1 I've got a method in DatabaseDAO to get all the values from the table public List<Category> getAllCategories() { database = dbHelper.getReadableDatabase(); List<Category> categories = new ArrayList<Category>(); Cursor cursor = database.query(SQLiteHelper.TABLE_CATEGORY, null, null, null, null, null, null); cursor.moveToFirst(); while(!cursor.isAfterLast()) { Category category = cursorToCategory(cursor); categories.add(category); cursor.moveToNext(); } cursor.close(); return categories; } Now adding the names to the group level is easy I do it the following way: ArrayList<String> groups; for(Category c : databaseDao.getAllCategories()) { groups.add(c.getName()); } Now I want to add the children to the ExpandableListView in the following array ArrayList<ArrayList<ArrayList<String>>> children;. How do I get the children under the correct group name? I think it has to do somenthing with groups.indexOf() but in the list table I only have a foreign category_id and not the actual name.

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• Improving Performance on this Image Creation function

  - by Abs

  Hello all, I am making use of GD2 and the image functions to take in a string and then convert that into an image using different fonts at different sizes. The function I use is below. Currently, its pretty quick but not quick enough. The function gets called about 20 times per user and the images generated are always new ones (different) so caching isn't going to help! I was hoping to get some ideas on how to make this function faster. Maybe supply more RAM to the script running? Anything else that is specific to this PHP function? Anything else that I can do to tweak performance of this function? function generate_image($save_path, $text, $font_path, $font_size){ $font = $font_path; /* * I have simplifed the line below, its actually a function that works out the size of the box * that is need for each image as the image size is different based on font type, font size etc */ $measure = array('width' => 300, 'height'=> 120); if($measure['width'] > 900){ $measure['width'] = 900; } $im = imagecreatetruecolor($measure['width'], $measure['height']); $white = imagecolorallocate($im, 255, 255, 255); $black = imagecolorallocate($im, 0, 0, 0); imagefilledrectangle($im, 0, 0, $measure['width'], $measure['height'], $white); imagettftext($im, $font_size, 0, $measure['left'], $measure['top'], $black, $font, ' '.$text); if(imagepng($im, $save_path)){ $status = true; }else{ $status = false; } imagedestroy($im); return $status; } Thanks all for any help

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• Aggregate Pattern and Performance Issues

  - by Mosh

  Hello, I have read about the Aggregate Pattern but I'm confused about something here. The pattern states that all the objects belonging to the aggregate should be accessed via the Aggregate Root, and not directly. And I'm assuming that is the reason why they say you should have a single Repository per Aggregate. But I think this adds a noticeable overhead to the application. For example, in a typical Web-based application, what if I want to get an object belonging to an aggregate (which is NOT the aggregate root)? I'll have to call Repository.GetAggregateRootObject(), which loads the aggregate root and all its child objects, and then iterate through the child objects to find the one I'm looking for. In other words, I'm loading lots of data and throwing them out except the particular object I'm looking for. Is there something I'm missing here? PS: I know some of you may suggest that we can improve performance with Lazy Loading. But that's not what I'm asking here... The aggregate pattern requires that all objects belonging to the aggregate be loaded together, so we can enforce business rules.

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• Improving field get and set performance with ASM or Javassist

  - by ng

  I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM and Javasist examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and one with Javassist? Any help would be greatly appreciated.

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• Reading from a database located in the Program Files folder using ODBC

  - by Dabblernl

  We have an application that stores its database files in a subfolder of the Program Files directory. These files are redirected to the VirtualStore in Vista and Windows 7. We represent data from the database using Microsoft DataReports (VB6). So far so good. But we now want to use Crystal Reports XI to represent data from the database. Our idea is to NOT pass this data to CR from our program, but to have CR retreive it from the database using a a system DSN through ODBC. In this way we hope to present our users with more flexibility in designing their own reports. What we do want to ensure though is that these system DSNs are configured correctly when the user installs our program or when the program calls the Crystal Report. Is there a smart way to do this using System variables for instance, instead of having to write a routine that checks for OS-version, whether UAC is enabled on the OS, whether the write restrictions on the Program Files folder have been lifted, etc and then adapts he System DSN to point to either the C:\Program Files\OurApp\Data folder, or the C:\Users\User\AppData\VirtualStore\Program Files\OurApp\Data folder? Suggestions for an entirely different approach are welcome too!

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• lots of backbone views - performance issues?

  - by ksol

  tl;dr: I wonder if having lots (100+ for the moment, potentially up to 1000/2000 or more) of backbone views (as a cell of a table) is too heavy or not The project I'm working on revolves around a planning view. There one row per user that covers 6 hours of a day, each hour splitted in 4 slots of 15mn. This planning is used to add "reservations" when clicking on a slot, and should handle hovering of the correct slots, and also handle when it is NOT possible to make a reservation - ie. prevent user click on an "unavailable" slot. There is many reasons why a slot can't be clicked on: the user is not available at this time, or the user is in a reservation; or the app needs to "force" a delay slot between two reservations. Reservations (a div) are rendered in a slot (a cell of a table), and by toying with dimensions, hovers the right number of slots. All this screen is handled with backbone. So For each slot I'm hovering on, I need to check wether I can do a reservation here or not. As of this moment, I use this by toying with the data attributes on the slots : when a reservation object is added, the slots covered are "enhanced with (among others) the reservation object (the backbone view object). But in some cases I don't quite have a grasp on now, it mixes up, and when the reservation view is removed, the slots are not "cleaned up" : the previous class is not reset correctly. It is probably something I've done wrong or badly, but this is only going to get heavier; I think I should use another class of Backbone views here, but I'm afraid the number of slots and thereof of views objects will be high and cause performance issue. I don't know mush about js perf so I'd like to have some feedback before jumping on that train. Any other advice on how to do this would be quite welcomed too. Thanks for your time. If this is not clear enough, tell me, I'll try and rephrase it.

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• NHibernate, legacy database, foreign keys that aren't

  - by Joe

  The project I'm working on has a legacy database with lots of information in it that's used to alter application behavior. Basically I'm stuck with something that I have to be super careful about changing. Onto my problem. In this database is a table and in this table is a column. This column contains integers and most of the pre-existing data have a value of zero for this column. The problem is that this column is in fact a foreign key reference to another entity, it was just never defined as such in the database schema. Now in my new code I defined my Fluent-NHibernate mapping to treat this column as a Reference so that I don't have to deal with entity id's directly in my code. This works fine until I come across an entity that has a value of 0 in this column. NHibernate thinks that a value of 0 is a valid reference. When my code tries to use that referenced object I get an ObjectNotFoundException as obviously there is no object in my database with an id of 0. How can I, either through mapping or some kind of convention (I'm using Fluent-nhibernate), get NHibernate to treat id's that are 0 the same as if it was NULL?

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• Cache data in SQL CE database

  - by user93422

  Background I have an SQL CE database, that is constantly updated (every second). I have a (web) application that allows a user to look at the data in real-time. At some point a user can click "take a snapshot" button, and it will open the snapshot in a different window. And then on that form, there is "print" and "download" buttons that will either generate a page for printing, or will stream the data as CSV file - but same data snapshot has to be used, i.e. I can't go to the DB to get latest data for that. Details SQL CE dabatase is exposed through WCF web service. Snapshot consists of up to 500 records, 10 columns each. Expiration time on the snapshot of 2 hours is sufficient. It is a low-traffic application, so I don't expect more than few (5) connections at the same time. Loosing snapshot is not a big deal, user can simply generate new one. database is accessed by self-hosted WCF web service using Linq-to-SQL. Web site is ASP.NET MVC hosted on UltiDev Cassini. database, and web site are most likely be on the same box, when deployed. The entire app is intranet bound. Problem I need to cache the snapshot of the data at the moment user pressed "take a snapshot" button, so that I can use same data to generate print page, or generate a file for download. Solution 1: Each time there is a need to generate a snapshot, I will create a table in the database. Since there are no temp tables in SQL CE, I will need to clean it up myself. Solution 2: Cache the snapshot in-memory on either DB server, or web server. Question: Is there anything wrong with proposed solutions? Any different solution suggestions?

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• Improving field get and set performance with ASM

  - by ng

  I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and maybe one with Javassist? Any help would be greatly appreciated.

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• Performance impact when using XML columns in a table with MS SQL 2008

  - by Sam Dahan

  I am using a simple table with 6 columns, 3 of which are of XML type, not schema-constrained. When the table reaches a size around 120,000 or 150,000 rows, I see a dramatic performance cost in doing any query in the table. For comparison, I have another table, which grows in size at about the same rate, but only contain scalar types (int, datetime, a few float columns). That table performs perfectly fine even after 200,000 rows. And by the way, I am not using XQuery on the xml columns, i am only using regular SQL query statements. Some specifics: both tables contain a DateTime field called SampleTime. a statement like (it's in a stored procedure but I show you the actual statement) SELECT MAX(sampleTime) SampleTime FROM dbo.MyRecords WHERE PlacementID=@somenumber takes 0 seconds on the table without xml columns, and anything from 13 to 20 seconds on the table with XML columns. That depends on which drive I set my database on. At the moment it sits on a different spindle (not C:) and it takes 13 seconds. Has anyone seen this behavior before, or have any hint at what I am doing wrong? I tried this with SQL 2008 EXPRESS and the full-blown SQL Server 2008, that made no difference. Oh, one last detail: I am doing this from a C# application, .NET 3.5, using SqlConnection, SqlReader, etc.. I'd appreciate some insight into that, thanks! Sam

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• VB.NET Update Access Database with DataTable

  - by sinDizzy

  I've been perusing some hep forums and some help books but cant seem to get my head wrapped around this. My task is to read data from two text files and then load that data into an existing MS Access 2007 database. So here is what i'm trying to do: Read data from first text file and for every line of data add data to a DataTable using CarID as my unique field. Read data from second text file and look for existing CarID in DataTable if exists update that row. If it doesnt exist add a new row. once im done push the contents of the DataTable to the database. What i have so far: Dim sSQL As String = "SELECT * FROM tblCars" Dim da As New OleDb.OleDbDataAdapter(sSQL, conn) Dim ds As New DataSet da.Fill(ds, "CarData") Dim cb As New OleDb.OleDbCommandBuilder(da) 'loop read a line of text and parse it out. gets dd, dc, and carId 'create a new empty row Dim dsNewRow As DataRow = ds.Tables("CarData").NewRow() 'update the new row with fresh data dsNewRow.Item("DriveDate") = dd dsNewRow.Item("DCode") = dc dsNewRow.Item("CarNum") = carID 'about 15 more fields 'add the filled row to the DataSet table ds.Tables("CarData").Rows.Add(dsNewRow) 'end loop 'update the database with the new rows da.Update(ds, "CarData") Questions: In constructing my table i use "SELECT * FROM tblCars" but what if that table has millions of records already. Is that not a waste of resources? Should i be trying something different if i want to update with new records? Once Im done with the first text file i then go to my next text file. Whats the best approach here: To First look for an existing record based on CarNum or to create a second table and then merge the two at the end? Finally when the DataTable is done being populated and im pushing it to the database i want to make sure that if records already exist with three primary fields (DriveDate, DCode, and CarNum) that they get updated with new fields and if it doesn't exist then those records get appended. Is that possible with my process? tia AGP

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• Update Datatable and DatagridView with database Changes by Timer

  - by aleroot

  Scenario : i have a database table that is being updated frequently by some services. I have a c# Winforms Application that load this table in a datagridview by binding a datatable as Datasource, then i whant to add a Timer that every 10 seconds update a the content of a datatable with the last changes in the database table ... I don't need to update a database with the datatable changes, but i need to update datatable with the last changes in the database table, that is the inverse of the usually.... Is there a way to do that ? What is the best way ? i've tried with this code : private void ServiceTimer_Tick(object state) { OdbcConnection oCon = new OdbcConnection(); oCon.ConnectionString = ConnectionStrings; OdbcDataAdapter dp = new OdbcDataAdapter("SELECT * FROM table", oCon); dsProva.Tables.Clear(); dp.Fill(dsProva,"table"); dataGridViewMessaggi.DataSource = dsProva.Tables["table"]; dataGridViewMessaggi.Refresh(); } But every Timer Tick i lost the selection in DatagridView and Current Row .... Is There a better solution ?

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• [C#]Update Datatable and DatagridView with database Changes by Timer

  - by aleroot

  Scenario : i have a database table that is being apdated frequently bey some services. I have a c# Winform Application that load this table in a datagridview by binding a datatable as Datasource, then i whant to add a Timer that every 10 seconds update a the content of a datatable with the last changes in the database table ... I don't need to update a database with the datatable changes, but i need to update datatable with the last changes in the database table, that is the inverse of the usually.... Is there a way to do that ? What is the best way ? i've tried with this code : private void ServiceTimer_Tick(object state) { OdbcConnection oCon = new OdbcConnection(); oCon.ConnectionString = ConnectionStrings; OdbcDataAdapter dp = new OdbcDataAdapter("SELECT * FROM table", oCon); dsProva.Tables.Clear(); dp.Fill(dsProva,"table"); dataGridViewMessaggi.DataSource = dsProva.Tables["table"]; dataGridViewMessaggi.Refresh(); } But every Timer Tick i lost the selection in DatagridView and Current Row .... Is There a better solution ?

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• Connect Rails model to non-rails database

  - by the_snitch

  I'm creating a new web application (Rails 3 beta), of which pieces of it will access data from a legacy mysql database that a current php application is using. I do not wish to modify the legacy db schema, I just want to be able to read/write to it, as well as the rails application having it's own database using activerecord for the newer stuff. I'm using mysql for the rails app, so I have the adapter installed. How is the best way to do this? For example, I want contacts to come from the old database. Should I create a contacts controller, and manually call sql to get the variables for the views? Or should I create a Contact model, and define attributes that match the fields in the database, and am I able to use it like Contact.mail_address to have it call "SELECT mailaddr FROM contacts WHERE id=Contact.id". Sorry, I've never done much in Rails outside of the standard stuff that is documented well. I'm not sure of what the best approach would be. Ideally, I want the contacts to be presented to my rails application as native as possible, so that I can expose them RESTfully for API access. Any suggestions and code examples would be much appreciated

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• Unable to insert DateTime format into database

  - by melvg

  I'm unable to insert the DateTime into my database. Am i writing the statement wrongly? Apparently without the DateTime, I am able to insert into the database string dateAndTime = date + " " + time; CultureInfo provider = CultureInfo.InvariantCulture; DateTime theDateTime = DateTime.ParseExact(dateAndTime, "d MMMM yyyy hh:mm tt", provider); //Create a connection, replace the data source name with the name of the SQL Anywhere Demo Database that you installed SAConnection myConnection = new SAConnection("UserID=dba;Password=sql;DatabaseName=emaDB;ServerName=emaDB"); //open the connection ; myConnection.Open(); //Create a command object. SACommand insertAccount = myConnection.CreateCommand(); //Specify a query. insertAccount.CommandText = ("INSERT INTO [meetingMinutes] (title,location,perioddate,periodtime,attenders,agenda,accountID,facilitator,datetime) VALUES ('"+title+"','" + location + "', '" + date + "','" + time + "', '" + attender + "','" + agenda + "', '" + accountID + "','" + facilitator + "','" +theDateTime+ "')"); try { insertAccount.ExecuteNonQuery(); if (title == "" || agenda == "") { btnSubmit.Attributes.Add("onclick", "displayIfSuccessfulInsert();"); //ScriptManager.RegisterStartupScript(this, GetType(), "error", "alert('Please ensure to have a title or agenda!');", true); } else { btnSubmit.Attributes.Add("onclick", "displayIfSuccessfulInsert();"); Response.Redirect("HomePage.aspx"); //ScriptManager.RegisterStartupScript(this, this.GetType(), "Redit", "alert('Minutes Created!'); window.location='" + Request.ApplicationPath + "/HomePage.aspx';", true); } } catch (Exception exception) { Console.WriteLine(exception); } finally { myConnection.Close(); } It does not insert the SQL into my database.

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• iPhone and iPad : Doing a "select * from something" query in a SQLite database

  - by Abramodj

  Hi folks, i'm trying to use the SQLite data base in my iPad app, and here's my function to make a query: - (void)executeQuery:(char*)query { NSString *file = [self getWritableDBPath]; NSFileManager *fileManager = [NSFileManager defaultManager]; BOOL success = [fileManager fileExistsAtPath:file]; // If its not a local copy set it to the bundle copy if(!success) { //file = [[NSBundle mainBundle] pathForResource:DATABASE_TITLE ofType:@"db"]; [self createEditableCopyOfDatabaseIfNeeded]; } dataArray = NULL; dataArray = [NSMutableArray array]; sqlite3 *database = NULL; if (sqlite3_open([file UTF8String], &database) == SQLITE_OK) { sqlite3_exec(database, query, loadTimesCallback, dataArray, NULL); } sqlite3_close(database); [self logResults]; } if I call [self executeQuery:"select name from table1"]; everything is working fine. But if i call [self executeQuery:"select * from cars"]; the app crashes telling me that the NSMutableArray dataArray is not the right kind of variable where to set the query results. So, how can i do a "select * form table1" query, and store the results? Thanks! EDIT: Here's my loadTimesCallback method: static int loadTimesCallback(void *context, int count, char **values, char **columns) { NSMutableArray *times = (NSMutableArray *)context; for (int i=0; i < count; i++) { const char *nameCString = values[i]; [times addObject:[NSString stringWithUTF8String:nameCString]]; } return SQLITE_OK; }

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• Slow performance with MVC2 DisplayFor

  - by PretzelSteelersFan

  I'm iterating through a collection on my view model. The collection contains HealthLifeDentalRates which implement IBeginsEnds. I have a Display Template BeginsEnds that displays the date range. This results in very slow performance. If I simply the date range (see commented code), it's fine. I think how I'm defining the lambda is the problem but not sure how to change it. <% foreach (var item in Model.Data.OrderBy(x=x.HealthLifeDentalRateCode)) { % <tr> <td> <%= Html.Encode(item.FiscalPeriodString()) %> </td> <td> <%= Html.Encode(item.HealthLifeDentalRateCode) %> </td> <td> <%= Html.Encode(item.Rate) %> </td> <td> <%= Html.Encode(item.IsDental.YesNo()) %> </td> <td> <%= Html.DisplayFor(i = item, "BeginsEnds") % - <%= Html.Encode(item.Ends.ToDateString()) % -- <%= Html.Encode(String.Format("{0:g}", item.Loaded)) % - <%= Html.Encode(item.LoadedBy) % <% } %>

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