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  • SQL query for active users

    - by user344513
    This SQL query gives me today's number of users active in the last 30 days: SELECT COUNT(*) FROM table.users WHERE creation_tsz >= (now() - interval '30 days') How can I modify it to get not a single value, but a table of active users for a range of dates? Thanks, Rob

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  • Dynamically find other hosts in a LAN in Java

    - by Federico Cristina
    A while ago I developed a little LAN chat app. in Java which allows chatting with other hosts, send images, etc. Although it was created just for fun, now it's being used where I work. Currently, there is no "chat server" on the app. where each client registers, updates it's status, etc. (I liked the idea of symmetric design and not depending on a server running on some other machine). Instead, each host is a client/server which has a hosts.properties file with the hostname of the other hosts, and - for instance - broadcasts to each one of them when sending a massive message/image/whatever. In the beginning there were just a couple of hosts, so this hosts.properties file wasn't an issue. But as the amount of users increased, the need of updating that file was a bit daunting. So now I've decided to get rid of it, and each time the app. starts, dynammically find the other active hosts. However, I cannot find the correct way of implement this. I've tried starting different threads, each one of them searching for other hosts in a known range of IP addresses. Something like this (simplified for the sake of readability): /** HostsLocator */ public static void searchForHosts(boolean waitToEnd) { for (int i=0; i < MAX_IP; i+= MAX_IP / threads) { HostsLocator detector = new HostsLocator(i, i+(MAX_IP / threads - 1)); // range: from - to new Thread(detector).start(); } } public void run() { for (int i=from; i<=to; i++) findHosts( maskAddress + Integer.toString(i) ); } public static boolean findHosts(String IP) { InetAddress address = InetAddress.getByName(IP); if ( address.isReachable(CONNECTION_TIME_OUT) ) // host found! } However: With a single thread and a low value in CONNECTION_TIME_OUT (500ms) I get wrong Host Not Found status for for hosts actually active. With a high value in CONNECTION_TIME_OUT (5000ms) and only one single thread takes forever to end With several threads I've also found problems similar like the first one, due to collisions. So... I guess there's a better way of solving this problem but I couldn't find it. Any advice? Thanks!

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  • Converting an empty string into nil in Ruby

    - by adi92
    I have a string called word and a function called infinitive such that word.infinitive would return another string on some occasions and an empty string otherwise I am trying to find an elegant ruby one line expression for the code-snippet below if word.infinitive == "" return word else return word.infinitive Had infinitive returned nil instead of "", I could have done something like (word.infinitive or word) But since it does not, I can't take advantage of the short-circuit OR Ideally I would want 1) a single expression that I could easily embed in other code 2) the function infinitive being called only once 3) to not add any custom gems or plugins into my code

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  • MATLAB plot moving data points in seperate subplots simutaneously

    - by Nate B.
    I wish to visualize the movement of a data point throughout space across a period of time within MATLAB. However, the way I want my figure to display is such that only a single instant is plotted at any given time. That was easy, I simply created a for loop to update my 3D plot display for every set of coordinates (x,y,z) in my data. However, I wish to display 4 different viewing angles of this plot at all times. I am well aware of how to setup subplots within MATLAB, that is not the issue. My issue is getting all 4 of these subplots to execute simultaneously so that all 4 subplots are always displaying the same point in time. I would appreciate if anyone could suggest how to handle this issue. As requested, my code for a figure with a single plot is shown below: datan = DATA; %data in form of x,y,z,a,b,c by column for row# of time points tib=zeros(size(datan,1),12); tib(:,1:3) = datan(:,1:3); tib_ref=tib(1,1:3); for i=1:size(datan,1) tib(i,1:3)=tib(i,1:3)-tib_ref; end angle_to_dircos close all figure('Name','Directions (Individual Cycles)','NumberTitle','off') for cc=1:2 hold off for bb=1:10:size(tib,1); scatter3(tib(bb,1),tib(bb,2),tib(bb,3),'green','filled'); %z and y axes are flipped in polhemus system hold on p0 = [tib(bb,1),tib(bb,2),tib(bb,3)]; p1 = [tib(bb,1)+10*tib(bb,4),tib(bb,2)+10*tib(bb,5),tib(bb,3)+10*tib(bb,6)]; p2 = [tib(bb,1)+10*tib(bb,7),tib(bb,2)+10*tib(bb,8),tib(bb,3)+10*tib(bb,9)]; p3 = [-(tib(bb,1)+100*tib(bb,10)),-(tib(bb,2)+100*tib(bb,11)),-(tib(bb,3)+100*tib(bb,12))]; vectarrow(p0,p1,1,0,0) hold on vectarrow(p0,p2,0,1,0) hold on vectarrow(p0,p3,0,0,1) hold on az = 90; el = 0; view(az, el); xlim([-50,50]); ylim([-50,50]); zlim([-50,50]); xlabel('distance from center in X'); ylabel('distance from center in Y'); zlabel('distance from center in Z'); title('XYZ Scatter Plots of Tracker Position'); hold on plot3(0,0,0,'sk','markerfacecolor',[0,0,0]); p0 = [0,0,0]; p1 = [10,0,0]; p2 = [0,10,0]; p3 = [0,0,100]; vectarrow(p0,p1,1,0,0) hold on vectarrow(p0,p2,0,1,0) hold on vectarrow(p0,p3,1,0,1) drawnow; end end

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  • coco2d tab view for multi player

    - by godzilla
    I am currently developing a card game for the iphone using cocas2d. I am currently in need of a tab view with each tab representing a player and his / her set of cards. Currently i have a single view representing just one player. It seems as though cocas2s is not really built do have multiple views, to do this and it would require some serious amount of hacking around with the code. What would be the most efficient way to accomplish this?

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  • UITableView Reusable cells

    - by Michael
    Can someone explain me the way reusable cells works for single table view? How many reusable cells a datasource should create? So far in all samples I've seen only one. Would one even need more?

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  • emacs, override indentation

    - by aaa
    hi. Hopefully simple question: I have multiply nested namespace: namespace first {namespace second {namespace third { // emacs indents three times // I want to intend here } } } so emacs indents to the third position. However I just want a single indentation. Is it possible to accomplish this effect simply? Thanks

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  • Using jquery to prevent resubmitting form

    - by Tony
    I use jquery's .submit() to intercept user's submit event, however I found a problem. When the user single click the submit button, the form is submitted normally, but if a user deliberately fast click it multiple times, it will submit multiple times, which will cause duplicated data in the database. What's the solution for this kind of problem ?

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  • The PROMOTE TRANSACTION request failed because there is no local transaction active.

    - by Mark J Miller
    Under what circumstances would I see the above message? I have a single call to SQL Server which is wrapped in a call to TransactionScope. In our development and QA environments MSDTC is turned off and the call succeeds fine. However, in our production environment with MSDTC turned on we are failing with this call. Is there something that would cause this when I am sure we are not looking at a distributed transaction call at all?

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  • What's the maximum number of operators you that can be used in an if statement?

    - by DMinGod
    Hi, i'm using jquery and I'm trying to validate a form. My question is - What is the maximum number of tests can you give in a single if statement. function cc_validate () { if ($("#name").val() == "" || $("#ship_name").val() == "" || $("#address").val() == "" || $("#city").val() == "" || $("#ship_city").val() == "" || $("#state").val() == "" || $("#ship_state").val() == "" || $("#postal_code").val() == "" || isNaN($("#postal_code").val()) || $("#phone").val() == "" || $("#ship_phone").val() == "" || isNaN($("#phone").val()) || isNaN($("#ship_phone").val()) || $("#mobile_number").val() == "" || $("#ship_mobile_number").val() == "" || isNaN($("#mobile_number").val()) || isNaN($("#ship_mobile_number").val()) || $("#email").val() == "") { return false; } else { return true; } }

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  • Store java.util.Calendar field into one column

    - by Rasika
    How to store java.util.Calendar field into one column with Datanucleus JDO. By default it is stored into two columns (millisecs, Timezone) with following JDO metadata. field name="startDate" serialized="true" embedded="true" persistence-modifier="persistent" What need to be changed in metadata to store it into single column (Timestamp)? Is it posible query (JDOQL) on calendar field when it is in two clumn?

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  • Expecting a LexBuffer<char> but given a LexBuffer<byte> The type 'char' does not match the type 'by

    - by user152518
    Type mismatch. Expecting a LexBuffer but given a LexBuffer The type 'char' does not match the type 'byte' This is the error message that I am getting while using fslex. I have tried manually checking every single occurrence of lexbuf and its type. It's LexBuffer everywhere. But still the compiler is giving me the above error. Can you please tell me why this error occurs and how to go about resolving it. Thanks, chandrasekhar

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  • MSSQL 2005: Update rows in a specified order (like ORDER BY)?

    - by JMTyler
    I want to update rows of a table in a specific order, like one would expect if including an ORDER BY clause, but MS SQL does not support the ORDER BY clause in UPDATE queries. I have checked out this question which supplied a nice solution, but my query is a bit more complicated than the one specified there. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) ORDER BY Parent.Depth DESC; So, what I'm hoping that you'll notice is that a single table (TableA) contains a hierarchy of rows, wherein one row can be the parent or child of any other row. The rows need to be updated in order from the deepest child up to the root parent. This is because TableA.ColA must contain an up-to-date concatenation of its own current value with the values of its children (I realize this query only concats with one child, but that is for the sake of simplicity - the purpose of the example in this question does not necessitate any more verbosity), therefore the query must update from the bottom up. The solution suggested in the question I noted above is as follows: UPDATE messages SET status=10 WHERE ID in (SELECT TOP (10) Id FROM Table WHERE status=0 ORDER BY priority DESC ); The reason that I don't think I can use this solution is because I am referencing column values from the parent table inside my subquery (see WHERE Child.ParentColB = Parent.ColB), and I don't think two sibling subqueries would have access to each others' data. So far I have only determined one way to merge that suggested solution with my current problem, and I don't think it works. UPDATE TableA AS Parent SET Parent.ColA = Parent.ColA + (SELECT TOP 1 Child.ColA FROM TableA AS Child WHERE Child.ParentColB = Parent.ColB ORDER BY Child.Priority) WHERE Parent.Id IN (SELECT Id FROM TableA ORDER BY Parent.Depth DESC); The WHERE..IN subquery will not actually return a subset of the rows, it will just return the full list of IDs in the order that I want. However (I don't know for sure - please tell me if I'm wrong) I think that the WHERE..IN clause will not care about the order of IDs within the parentheses - it will just check the ID of the row it currently wants to update to see if it's in that list (which, they all are) in whatever order it is already trying to update... Which would just be a total waste of cycles, because it wouldn't change anything. So, in conclusion, I have looked around and can't seem to figure out a way to update in a specified order (and included the reason I need to update in that order, because I am sure I would otherwise get the ever-so-useful "why?" answers) and I am now hitting up Stack Overflow to see if any of you gurus out there who know more about SQL than I do (which isn't saying much) know of an efficient way to do this. It's particularly important that I only use a single query to complete this action. A long question, but I wanted to cover my bases and give you guys as much info to feed off of as possible. :) Any thoughts?

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  • How can you dispatch on request method in Django URLpatterns?

    - by rcampbell
    It's clear how to create a URLPattern which dispatches from a URL regex: (r'^books/$', books), where books can further dispatch on request method: def books(request): if request.method == 'POST': ... else ... I'd like to know if there is an idiomatic way to include the request method inside the URLPattern, keeping all dispatch/route information in a single location, such as: (r'^books/$', GET, retrieve-book), (r'^books/$', POST, update-books), (r'^books/$', PUT, create-books),

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  • Spring.Net Message Selectors with compound statements don't seem to be working

    - by Jonathan Beerhalter
    I'm using Spring.NET to connect to ActiveMQ and do some fairly simple pub sub routing. Everything works fine when my selector is a simple expression like Car='Honda' but if I try a compound expression like Car='Honda' AND Make='Pilot' I never get any matches on my subscription. Here's the code to generate the subscription, does anyone see where I might be doing something wrong? public bool AddSubscription(string topicName, Dictionary<string,string> selectorList, GDException exp) { try { ActiveMQTopic topic = new ActiveMQTopic(topicName); string selectorString = ""; if (selectorList.Keys.Count == 0) { // Select all items for this topic selectorString = "2>1"; } else { foreach (string key in selectorList.Keys) { selectorString += key + " = '" + selectorList[key] + "'" + " AND "; } selectorString = selectorString.Remove(selectorString.Length - 5, 5); } IMessageConsumer consumer = this._subSession.CreateConsumer(topic, selectorString, false); if (consumer != null) { _consumers.Add(consumer); consumer.Listener += new MessageListener(HandleRecieveMessage); return true; } else { exp.SetValues("Error adding subscription, null consumer returned"); return false; } } catch (Exception ex) { exp.SetValues(ex); return false; } } And then the code to send the message, which seems simple enough to me public void SendMessage(GDPubSubMessage messageToSend) { if (!this.isDisposed) { if (_producers.ContainsKey(messageToSend.Topic)) { IBytesMessage bytesMessage = this._pubSession.CreateBytesMessage(messageToSend.Payload); foreach (string key in messageToSend.MessageProperties.Keys) { bytesMessage.Properties.SetString(key, messageToSend.MessageProperties[key]); } _producers[messageToSend.Topic].Send(bytesMessage, false, (byte)255, TimeSpan.FromSeconds(1)); } else { ActiveMQTopic topic = new ActiveMQTopic(messageToSend.Topic); _producers.Add(messageToSend.Topic, this._pubSession.CreateProducer(topic)); IBytesMessage bytesMessage = this._pubSession.CreateBytesMessage(messageToSend.Payload); foreach (string key in messageToSend.MessageProperties.Keys) { bytesMessage.Properties.SetString(key, messageToSend.MessageProperties[key]); } _producers[messageToSend.Topic].Send(bytesMessage); } } else { throw new ObjectDisposedException(this.GetType().FullName); } } 07/102009: Update Ok, found the problem bytesMessage.Properties.SetString(key, messageToSend.MessageProperties[key]); This justs sets a single property, so my messages are only being tagged with a single property, hence the combo subscription never gets hit. Anyone know how to add more properties? You'd think bytesMessage.Properties would have a Add method, but it doesn't.

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  • Can I integrate many sources into one RSS reader?

    - by BenAlabaster
    I'm looking to integrate a bunch of RSS/ATOM sources into a feed for our intranet. This is outside my usual realm of work so I've had very limited exposure to this. I'd like to integrate all the feeds into a single reader such that all the news items are in chronological release order. Is this doable? Do I need a special component? Or can I make the ASP.NET integrated components do all this simply enough?

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  • Why is a .net generic dictionary so big

    - by thefroatgt
    I am serializing a generic dictionary in VB.net and I am very surprised that it is about 1.3kb with a single item. Am I doing something wrong, or is there something else I should be doing? I have a large number of dictionaries and it is killing me to send them all across the wire. The code I use for serialization is Dim dictionary As New Dictionary(Of Integer, Integer) Dim stream As New MemoryStream Dim bformatter As New BinaryFormatter() dictionary.Add(1, 1) bformatter.Serialize(stream, dictionary) Dim len As Long = stream.Length

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  • Updating protected attributes using update_all

    - by Jack
    Since you cannot use the normal 'update' and 'update_attribute' methods from ActiveRecord to update a protected attribute, is the following the best way to update an attribute for a single user? User.update_all("admin = true","id = 1") I'm guessing this doesn't lie in the 'best practice' category, so I'm just curious if there is a more appropriate way.

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  • Two Phase Commit with MongoDB

    - by mattcodes
    Heres what Im thinking. Do you see any issues with this workaround to emulate 2 phase commit when using something like MongoDB where each operation is atomic and there is no support for transactions outside of that? transaction_scope: read message from servicebus - UpdateCustomerAddress get customer aggregate from docdb, replay events where commited =1 call customer.updateAddress validates creates customer address updated event apply event event store as uncommitted events do optimistic concurrency update against docdb pushing uncommitted events (single op to ensure consistency) publish event to service bus update docdb set events just published to commited = 1 (again one 1 op - at least in mongodb) transaction_complete

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