Search Results

Search found 15621 results on 625 pages for 'creating'.

Page 508/625 | < Previous Page | 504 505 506 507 508 509 510 511 512 513 514 515  | Next Page >

• Null reference exceptions in .net

  - by Carlo

  Hello, we're having this big problem with our application. It's a rather large application with several modules, and thousands and thousands lines of code. A lot of parts of the application are designed to exist only with a reference to another object, for example a Person object can never exists without a House object, so if you at any point in the app say: bool check = App.Person.House == null; check should always be false (by design), so, to keep using that example, while creating modules, testing, debugging, App.Person.House is never null, but once we shipped the application to our client, they started getting a bunch of NullReferenceException with the objects that by design, should never have a null reference. They tell us the bug, we try to reproduce it here, but 90% of the times we can't, because here it works fine. The app is being developed with C# and WPF, and by design, it only runs on Windows XP SP 3, and the .net framework v3.5, so we KNOW the user has the same operative system, service pack, and .net framework version as we do here, but they still get this weird NullReferenceExceptions that we can't reproduce. So, I'm just wondering if anyone has seen this before and how you fixed it, we have the app running here at least 8 hours a day in 5 different computers, and we never see those exceptions, this only happens to the client for some reason. ANY thought, any clue, any solution that could get us closer to fixing this problem will be greatly appreciated. Thanks!

  Read the article

• Rails wont install at create Makefile stage

  - by mattc

  I am getting this error after running sudo gem install rails /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb creating Makefile make xcrun cc -I. - I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin12.0 -I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin12.0 -I. -DJSON_GENERATOR -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -fno-common -arch i386 -arch x86_64 -g -O3 -pipe -fno-common -DENABLE_DTRACE -fno-common -pipe -fno-common -c generator.c xcrun: Error: failed to exec real xcrun. (No such file or directory) cc -arch i386 -arch x86_64 -pipe -bundle -undefined dynamic_lookup -o generator.bundle generator.o -L. -L/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib -L. -arch i386 -arch x86_64 -lruby -lpthread -ldl -lobjc i686-apple-darwin11-llvm-gcc-4.2: generator.o: No such file or directory i686-apple-darwin11-llvm-gcc-4.2: generator.o: No such file or directory lipo: can't figure out the architecture type of: /var/tmp//ccHCNNwM.out make: *** [generator.bundle] Error 1 I have Homebrew installed, Xcode 4.4 with command line tools installed, Osx 10.6.2 I run gem env and get this but not sure what I'm looking for: RubyGems Environment: - RUBYGEMS VERSION: 1.8.24 - RUBY VERSION: 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0] - INSTALLATION DIRECTORY: /Library/Ruby/Gems/1.8 - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby - EXECUTABLE DIRECTORY: /usr/bin - RUBYGEMS PLATFORMS: - ruby - universal-darwin-12 - GEM PATHS: - /Library/Ruby/Gems/1.8 - /Users/matthewcleghorn/.gem/ruby/1.8 - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8 - GEM CONFIGURATION: - :update_sources => true - :verbose => true - :benchmark => false - :backtrace => false - :bulk_threshold => 1000 - REMOTE SOURCES: - http://rubygems.org/ Any help greatly appreciated. Thanks.

  Read the article

• LuaEdit can't find module when Lua files all in the same folder

  - by joverboard

  I downloaded LuaEdit to use as an IDE and debug tool however I'm having trouble using it for even the simplest things. I've created a solution with 2 files in it, all of which are stored in the same folder. My files are as follows: --startup.lua require("foo") test("Testing", "testing", "one, two, three") --foo.lua foo = {} print("In foo.lua") function test(a,b,c) print(a,b,c) end This works fine when in my C++ compiler when accessed through some embed code, however when I attempt to use the same code in LuaEdit, it crashes on line 3 require("foo") with an error stating: module 'foo' not found: no field package.preload['foo'] no file 'C:\Program Files (x86)\LuaEdit 2010\lua\foo.lua' no file 'C:\Program Files (x86)\LuaEdit 2010\lua\foo\init.lua' no file 'C:\Program Files (x86)\LuaEdit 2010\foo.lua' no file 'C:\Program Files (x86)\LuaEdit 2010\foo\init.lua' no file '.\foo.lua' no file 'C:\Program Files (x86)\LuaEdit 2010\foo.dll' no file 'C:\Program Files (x86)\LuaEdit 2010\loadall.dll' no file '.\battle.dll' I have also tried creating these files prior to adding them to a solution and still get the same error. Is there some setting I'm missing? It would be great to have an IDE/debugger but it's useless to me if it can't run linked functions.

  Read the article

• OpenAL not playing on Max OS X 10.6

  - by Grimless

  I've been working on getting a basic audio engine running on my Mac using OpenAL. It seems relatively straightforward after working with OpenGL for a while. However, despite the fact that I believe I have everything in place, my sound will not play. Here is the order of things I am doing: //Creating a new device ALCdevice* device = alcOpenDevice(NULL); //Create a new context with the device ALCcontext* context = alcCreateContext(device, NULL); //Make that context current alcMakeContextCurrent(context); //Do lots of loading stuff to bring in an AIFF... voodooAIFF = myAIFFLoader("name"); //Then use that data ALuint buf; alGenBuffers(1, &buf); //Check for errors, but none happen... //Bind buffer data. alBufferData(buf, voodooAIFF.format, voodooAIFF.data, voodooAIFF.sizeInBytes, voodooAIFF.frequency); //Check for errors, none here either... //Create Source ALuint src; alGenSources(1, &src); //Error check again, no errors. //Bind source to buffer alSourcei(src, AL_BUFFER, buf); //Set reference distance alSourcei(sourceID, AL_REFERENCE_DISTANCE, 1); //Set source attributes including gain and pitch to 1 (direction set to 0,0,0) //Check for errors, nothing... //Set up listener attributes. //Check for errors, no errors. //Begin playing. alSourcePlay(src); Observe silence... Any insight, what steps am I missing here?

  Read the article

• Matplotlib autodatelocator custom date formatting?

  - by jawonlee

  I'm using Matplotlib to dynamically generate .png charts from a database. The user may set as the x-axis any given range of datetimes, and I need to account for all of it. While Matplotlib has the dates.AutoDateLocator(), I want the datetime format printed on the chart to be context-specific - e.g. if the user is charting from 3 p.m. to 5 p.m., the year/month/day information doesn't need to be displayed. Right now, I'm manually creating Locator and Formatter objects thusly: def get_ticks(start, end): from datetime import timedelta as td delta = end - start if delta <= td(minutes=10): loc = mdates.MinuteLocator() fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(minutes=30): loc = mdates.MinuteLocator(byminute=range(0,60,5)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(hours=1): loc = mdates.MinuteLocator(byminute=range(0,60,15)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(hours=6): loc = mdates.HourLocator() fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(days=1): loc = mdates.HourLocator(byhour=range(0,24,3)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(days=3): loc = mdates.HourLocator(byhour=range(0,24,6)) fmt = mdates.DateFormatter('%I:%M %p') elif delta <= td(weeks=2): loc = mdates.DayLocator() fmt = mdates.DateFormatter('%b %d') elif delta <= td(weeks=12): loc = mdates.WeekdayLocator() fmt = mdates.DateFormatter('%b %d') elif delta <= td(weeks=52): loc = mdates.MonthLocator() fmt = mdates.DateFormatter('%b') else: loc = mdates.MonthLocator(interval=3) fmt = mdates.DateFormatter('%b %Y') return loc,fmt Is there a better way of doing this?

  Read the article

• ipad full screen (1024x768) animation with around 1800 frames fps problem

  - by Muhammad Farhan

  Hi there. what i am trying to do is to play a full screen(1024x768) animation on ipad with an fps of around 20. i have got a scene with 1800 full screen frames. till now i have tried a lot of approaches but have encountered a lot of problems. my first approach was to get the texture using the following function t = [[CCTexture2D alloc] initWithImage:[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:[NSString stringWithFormat:@"(%d)",startIndex] ofType:type]]]; give it to sprite by using setTexture method and then release the texture then create a new texture with next frame and repeat the procedure but by using this approach i only get an FPS of about 7. my second approach was to preload about 10 textures in texturecache save them in an array and give them to sprite using setTexture and on the back end i am replacing the old textures with the new texture in a thread but the problem i face is that creating new texture and adding to array takes some time and when the settexture method is called the sprite displays the old texture because the new one is not loaded yet but after some time new texture get loaded. Is there any way i can run a full screen animation on ipad at around 20 fps plesae help me out. Thanks Farhan

  Read the article

• Is a call to the following method considered late binding?

  - by AspOnMyNet

  1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

  Read the article

• How to use setTimeout / .delay() to wait for typing between characters

  - by Darcy

  Hi all, I am creating a simple listbox filter that takes the user input and returns the matching results in a listbox via javascript/jquery (roughly 5000+ items in listbox). Here is the code snippet: var Listbox1 = $('#Listbox1'); var commands = document.getElementById('DatabaseCommandsHidden'); //using js for speed $('#CommandsFilter').bind('keyup', function() { Listbox1.children().remove(); for (var i = 0; i < commands.options.length; i++) { if (commands.options[i].text.toLowerCase().match($(this).val().toLowerCase())) { Listbox1.append($('<option></option>').val(i).html(commands.options[i].text)); } } }); This works pretty well, but slows down somewhat when the 1st/2nd char's are being typed since there are so many items. I thought a solution I could use would be to add a delay to the textbox that prevents the 'keyup' event from being called until the user stops typing. The problem is, I'm not sure how to do that, or if its even a good idea or not. Any suggestions/help is greatly appreciated.

  Read the article

• What Do You Need To Write Your Own Blog Engine?

  - by deworde

  I've been messing around with basic websites for a few years, using companies like www.Fasthosts.co.uk to do my web hosting. But I'd like to expand my skills from C++ and Java app programming into Web-based programming, and I think the best way to do that is with a project. I've chosen to go with a blog engine because it's a relative comprehensive yet non-complex project. I'm aware that you can just go to Blogger and bam! One blog. I've done that, so that I can at least have some content, and work out what I want to do with this blog. At the moment, I'm thinking I'll use it to chart my progress creating the blogging engine. But I have some questions. Do you need to be running your own server? Or is it more sensible in the short-term to use a hosting company? What types of language are worth considering? What's important to focus on from a design perspective? What unexpected problems might I encounter?

  Read the article

• Practical non-image based CAPTCHA approaches?

  - by Jeff Atwood

  It looks like we'll be adding CAPTCHA support to Stack Overflow. This is necessary to prevent bots, spammers, and other malicious scripted activity. We only want human beings to post or edit things here! We'll be using a JavaScript (jQuery) CAPTCHA as a first line of defense: http://docs.jquery.com/Tutorials:Safer_Contact_Forms_Without_CAPTCHAs The advantage of this approach is that, for most people, the CAPTCHA won't ever be visible! However, for people with JavaScript disabled, we still need a fallback and this is where it gets tricky. I have written a traditional CAPTCHA control for ASP.NET which we can re-use. However, I'd prefer to go with something textual to avoid the overhead of creating all these images on the server with each request. I've seen things like.. ASCII text captcha: \/\/(_)\/\/ math puzzles: what is 7 minus 3 times 2? trivia questions: what tastes better, a toad or a popsicle? Maybe I'm just tilting at windmills here, but I'd like to have a less resource intensive, non-image based <noscript> compatible CAPTCHA if possible. Ideas?

  Read the article

• How can I make an event created through Google Calendar's API send an invitation email?

  - by Cebjyre

  I'm trying to create an event through the API and it is mostly working, with the exception that while the new events are being created in the invitees calendars, no emails are being sent. Creating the event from the web interface is pushing the event through, as well as sending the email (except one account that doesn't get any notifications at all, but that's not relevant to my current problem). The event I am trying to push in is: <entry xmlns='http://www.w3.org/2005/Atom' xmlns:gd='http://schemas.google.com/g/2005'> <category scheme='http://schemas.google.com/g/2005#kind' term='http://schemas.google.com/g/2005#event'></category> <title type='text'>test event</title> <content type='text'>content.</content> <gd:transparency value='http://schemas.google.com/g/2005#event.opaque'> </gd:transparency> <gd:eventStatus value='http://schemas.google.com/g/2005#event.confirmed'> </gd:eventStatus> <gd:where valueString='somewhere'></gd:where> <gd:who email="[redacted]" rel='http://schemas.google.com/g/2005#event.attendee' valueString='Me'><gd:attendeeStatus value='http://schemas.google.com/g/2005#event.invited'/></gd:who> <gd:who email="[redacted again]" rel='http://schemas.google.com/g/2005#event.organizer' valueString='Also Me'><gd:attendeeStatus value='http://schemas.google.com/g/2005#event.accepted'/></gd:who> <gd:when startTime='2010-05-18T15:30:00.000+10:00' endTime='2010-05-18T16:00:00.000+10:00'></gd:when> </entry> And when I request event lists I can't see any large difference between events created through the API and through the web interface.

  Read the article

• Getting unhandled exception when DataTemplate is created dynamically using Silverlight 3.0

  - by Bhaskar

  Requirement is to create a reusable multi-select combobox custom control. To accomplish this, I am creating the DataTemplate dynamically through code and set the combobox ItemTemplate. I am able to load the datatemplate dynamically and set the ItemTemplate, but getting unhandled exception (code: 7054) when combobox is selected. Here is the code Class MultiSelCombBox: ComboBox { public override void OnApplyTemplate() { base.OnApplyTemplate(); CreateTemplate(); } void CreateTemplate() { DataTemplate dt = null; if (CreateItemTemplate) { if (string.IsNullOrEmpty(CheckBoxBind)) { dt = XamlReader.Load(@"<DataTemplate xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""DropDownTemplate""><Grid xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""CheckboxGrid""><TextBox xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' x:Name=""test"" xml:space=""preserve"" Text='{Binding " + TextContent + "}'/></Grid></DataTemplate>") as DataTemplate; this.ItemTemplate = dt; } } } //Other code goes here }} what am i doing wrong? suggestion?

  Read the article

• Setting up Inversion of Control (IoC) in ASP.NET MVC with Castle Windsor

  - by Lirik

  I'm going over Sanderson's Pro ASP.NET MVC Framework and in Chapter 4 he discusses Creating a Custom Controller Factory and it seems that the original method, AddComponentLifeStyle or AddComponentWithLifeStyle, used to register controllers is deprecated now: public class WindsorControllerFactory : DefaultControllerFactory { IWindsorContainer container; public WindsorControllerFactory() { container = new WindsorContainer(new XmlInterpreter(new ConfigResource("castle"))); // register all the controller types as transient var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; //[Obsolete("Use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)) instead.")] //IWindsorContainer AddComponentLifeStyle<I, T>(string key, LifestyleType lifestyle) where T : class; foreach (Type t in controllerTypes) { container.Register(Component.For<IController>().ImplementedBy<???>().Named(t.FullName).LifeStyle.Is(LifestyleType.Transient)); } } // Constructs the controller instance needed to service each request protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } The new suggestion is to use Register(Component.For<I>().ImplementedBy<T>().Named(key).Lifestyle.Is(lifestyle)), but I can't figure out how to present the implementing controller type in the ImplementedBy<???>() method. I tried ImplementedBy<t>() and ImplementedBy<typeof(t)>(), but I can't find the appropriate way to pass int he implementing type. Any ideas?

  Read the article

• Ninject: Shared DI/IoC container

  - by joblot

  Hi I want to share the container across various layers in my application. I started creating a static class which initialises the container and register types in the container. public class GeneralDIModule : NinjectModule { public override void Load() { Bind().To().InSingletonScope(); } } public abstract class IoC { private static IKernel _container; public static void Initialize() { _container = new StandardKernel(new GeneralDIModule(), new ViewModelDIModule()); } public static T Get<T>() { return _container.Get<T>(); } } I noticed there is a Resolve method as well. What is the difference between Resolve and Get? In my unit tests I don’t always want every registered type in my container. Is there a way of initializing an empty container and then register types I need. I’ll be mocking types as well in unit test so I’ll have to register them as well. There is an Inject method, but it says lifecycle of instance is not managed? Could someone please set me in right way? How can I register, unregister objects and reset the container. Thanks

  Read the article

• How to ensure DB security for a Windows Forms application?

  - by Vilx-

  The basic setup is classic - you're creating a Windows Forms application that connects to a DB and does all kinds of enterprise-y stuff. Naturally, such an application will have many users with different access rights in the DB, and each with their own login name and password. So how do you implement this? One way is to create a DB login for every application user, but that's a pretty serious thing to do, which even requires admin rights on the DB server, etc. If the DB server hosts several applications, the admins are quite likely not to be happy with this. In the web world typically one creates his own "Users" table which contains all the necessary info, and uses one fixed DB login for all interaction. That is all nice for a web app, but a windows forms can't hide this master login information, negating security altogether. (It can try to hide, but all such attempts are easily broken with a bit of effort). So... is there some middle way? Perhaps logging in with a fixed login, and then elevating priviledges from a special stored procedure which checks the username and password?

  Read the article

• Dynamic Method Creation

  - by TJMonk15

  So, I have been trying to research this all morning, and have had no luck. I am trying to find a way to dynamically create a method/delegate/lambda that returns a new instance of a certain class (not known until runtime) that inherits from a certain base class. I can guarantee the following about the unknown/dynamic class It will always inherit from one known Class (Row) It will have atleast 2 constructors (one accepting a long, and one accepting an IDataRecord) I plan on doign the following: Finding all classes that have a certain attribute on them Creating a delegate/method/lambda/whatever that creates a new instance of the class Storing the delegate/whatever along with some properties in a struct/class Insert the struct into a hashtable When needed, pull the info out of the hashtable and calling the delegate/whatever to get a new instance of the class and returning it/adding it to a list/etc. I need help only with #2 above!!! I have no idea where to start. I really just need some reference material to get me started, or some keywords to throw into google. This is for a compact/simple to use ORM for our office here. I understand the above is not simple, but once working, should make maintaining the code incredibly simple. Please let me know if you need any more info! And thanks in advance! :)

  Read the article

• How to create more complex Lucene query strings?

  - by boris callens

  This question is a spin-off from this question. My inquiry is two-fold, but because both are related I think it is a good idea to put them together. How to programmatically create queries. I know I could start creating strings and get that string parsed with the query parser. But as I gather bits and pieces of information from other resources, there is a programattical way to do this. What are the syntax rules for the Lucene queries? --EDIT-- I'll give a requirement example for a query I would like to make: Say I have 5 fields: First Name Last Name Age Address Everything All fields are optional, the last field should search over all the other fields. I go over every field and see if it's IsNullOrEmpty(). If it's not, I would like to append a part of my query so it adds the relevant search part. First name and last name should be exact matches and have more weight then the other fields. Age is a string and should exact match. Address can varry in order. Everything can also varry in order. How should I go about this?

  Read the article

• Get Classic ASP variale from posted JSON

  - by Will

  I'm trying to post JSON via AJAX to a Classic ASP page, which retrieves the value, checks a database and returns JSON to the original page. I can post JSON via AJAX I can return JSON from ASP I can't retrieve the posted JSON into an ASP variable POST you use Request.Form, GET you use Request.Querystring......... what do I use for JSON? I have JSON libraries but they only show creating a string in the ASP script and then parsing that. I need to parse JSON from when being passed an external variable. Javascipt var thing = $(this).val(); $.ajax({ type: "POST", url: '/ajax/check_username.asp', data: "{'userName':'" + thing + "'}", contentType: "application/json; charset=utf-8", dataType: "json", cache: false, async: false, success: function() { alert('success'); }); ASP file (check_username.asp) Response.ContentType = "application/json" sEmail = request.form() -- THE PROBLEM Set oRS = Server.CreateObject("ADODB.Recordset") SQL = "SELECT SYSUserID FROM WCE_UK.dbo.t_SYS_User WHERE Username='"&sEmail&"'" oRS.Open SQL, oConn if not oRS.EOF then sStatus = (new JSON).toJSON("username", true, false) else sStatus = (new JSON).toJSON("username", false, false) end if response.write sStatus

  Read the article

• Turning on multiple result sets in an ODBC connection to SQL Server

  - by David Griffiths

  I have an application that originally needed to connect to Sybase (via ODBC), but I've needed to add the ability to connect to SQL Server as well. As ODBC should be able to handle both, I thought I was in a good position. Unfort, SQL Server will not let me, by default, nest ODBC commands and ODBCDataReaders - it complains the connection is busy. I know that I had to specify that multiple active result sets (MARS) were allowed in similar circumstances when connecting to SQL Server via a native driver, so I thought it wouldn't be an issue. The DSN wizard has no entr y when creating a SystemDSN. Some people have provided registry hacks to get around this, but this did not work (add a MARS_Connection with a value of Yes to HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI\system-dsn-name). Another suggestion was to create a file-dsn, and add "MARS_Connection=YES" to that. Didn't work. Finally, a DSN-less connection string. I've tried this one (using MultipleActiveResultSets - same variable as a Sql Server connection would use), "Driver={SQL Native Client};Server=xxx.xxx.xxx.xxx;Database=someDB;Uid=u;Pwd=p;MultipleActiveResultSets=True;" and this one: "Driver={SQL Native Client};Server=192.168.75.33\\ARIA;Database=Aria;Uid=sa;Pwd=service;MARS_Connection=YES;" I have checked the various connection-string sites - they all suggest what I've already tried.

  Read the article

• Disadvantages of MySQL Row Locking

  - by Nyxynyx

  I am using row locking (transactions) in MySQL for creating a job queue. Engine used is InnoDB. SQL Query START TRANSACTION; SELECT * FROM mytable WHERE status IS NULL ORDER BY timestamp DESC LIMIT 1 FOR UPDATE; UPDATE mytable SET status = 1; COMMIT; According to this webpage, The problem with SELECT FOR UPDATE is that it usually creates a single synchronization point for all of the worker processes, and you see a lot of processes waiting for the locks to be released with COMMIT. Question: Does this mean that when the first query is executed, which takes some time to finish the transaction before, when the second similar query occurs before the first transaction is committed, it will have to wait for it to finish before the query is executed? If this is true, then I do not understand why the row locking of a single row (which I assume) will affect the next transaction query that would not require reading that locked row? Additionally, can this problem be solved (and still achieve the effect row locking does for a job queue) by doing a UPDATE instead of the transaction? UPDATE mytable SET status = 1 WHERE status IS NULL ORDER BY timestamp DESC LIMIT 1

  Read the article

• What's the most DRY-appropriate way to execute an SQL command?

  - by Sean U

  I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

  Read the article

• Powershell scripts to backup SQL, SVN

  - by bszom

  I'm trying to use PowerShell to create some backups, and then to copy these to a web folder (or, in other words, upload them to a WebDAV share). At first I thought I'd do the WebDAV stuff from within PowerShell, but it seems this still requires a fair amount of "manual labour", ie: constructing HTTP requests. I then settled for creating a web folder from the script and letting Windows handle the WebDAV stuff. It seems that all it takes to create a web folder is to create a standard shortcut, as described here. What I can't figure out is how to actually copy files to the shortcut's target..? Maybe I'm going about this the wrong way. It would be ideal if I could somehow encrypt the credentials for the WebDAV in the script, then have it create the web folder, shunt over the files, and delete the web folder again. Or even better, not use a web folder at all. Third option would be to just create the web folder manually and leave it there, though I'd rather not. Any ideas/pointers/tips? :)

  Read the article

• Ideal directory structure for web application

  - by rno

  I'm about to create a user based website and will have to store photo, docs and other data for each user. If I take a silly number like 1 000 000 000 users, I believe than one folder with 1 000 000 000 won't be the fastest thing in the world! So I was thinking of creating something like 1st level : [a-z] 2nd level : [a-z] 3rd level : [a-z] Therefor bobby will be in /b/o/b/by But this also mean that it won't be spread equaly, because there will be very few user starting with a z and many more with a m,s,l ... so I was thinking of using a user id such as "000000000001", "000000000001" etc... 1st level : [000-999] 2nd level : [000-999] 3rd level : [000-999] therefore data of the user 000000000001 will be store in /data/000/000/000/001 then I will be sure to have a maximum of 1000 folder in each level. What do you guys think about it, what I should do or not do ? The server will be running Centos 5.4 with EXT3 on raid 1, if the I/O get's too bad i will probably go for a raid 10.

  Read the article

• Logic for family tree program

  - by david robers

  Hi All, I am creating a family tree program in Java, or at least trying to. I have developed several classes: Person - getters and setter for name gender age etc FamilyMember - extends Person getters and setters for setting arents and children Family - which consists of multiple family members and methods for adding removing members FamilyTree which is the main class for setting relationships. I have two main problems: 1) I need to set the relationships between people. Currently I am doing: FamilyMember A, FamilyMember B B.setMother(A); A.setChild(B); The example above is for setting a mother child relationship. This seems very clunky. Its getting very long winded to implement all relationships. Any ideas on how to implement multiple relationships in a less prodcedural way? 2) I have to be able to display the family tree. How can I do this? Are there any custom classes out there to make life easier? Thanks for your time...

  Read the article

• iOS: Assignment to iVar in Block (ARC)

  - by manmal

  I have a readonly property isFinished in my interface file: typedef void (^MyFinishedBlock)(BOOL success, NSError *e); @interface TMSyncBase : NSObject { BOOL isFinished_; } @property (nonatomic, readonly) BOOL isFinished; and I want to set it to YES in a block at some point later, without creating a retain cycle to self: - (void)doSomethingWithFinishedBlock:(MyFinishedBlock)theFinishedBlock { __weak MyClass *weakSelf = self; MyFinishedBlock finishedBlockWrapper = ^(BOOL success, NSError *e) { [weakSelf willChangeValueForKey:@"isFinished"]; weakSelf -> isFinished_ = YES; [weakSelf didChangeValueForKey:@"isFinished"]; theFinishedBlock(success, e); }; self.finishedBlock = finishedBlockWrapper; // finishedBlock is a class ext. property } I'm unsure that this is the right way to do it (I hope I'm not embarrassing myself here ^^). Will this code leak, or break, or is it fine? Perhaps there is an easier way I have overlooked? SOLUTION Thanks to the answers below (especially Krzysztof Zablocki), I was shown the way to go here: Define isFinished as readwrite property in the class extension (somehow I missed that one) so no direct ivar assignment is needed, and change code to: - (void)doSomethingWithFinishedBlock:(MyFinishedBlock)theFinishedBlock { __weak MyClass *weakSelf = self; MyFinishedBlock finishedBlockWrapper = ^(BOOL success, NSError *e) { MyClass *strongSelf = weakSelf; strongSelf.isFinished = YES; theFinishedBlock(success, e); }; self.finishedBlock = finishedBlockWrapper; // finishedBlock is a class ext. property }

  Read the article

< Previous Page | 504 505 506 507 508 509 510 511 512 513 514 515  | Next Page >