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• How to structure a database with questions and answers?

  - by Andreas Johannessen

  Hi I am going to make a simple application that uses a database. I could need some guidance on how to structure it. I shall make question program. What I have in mind is. One table with questions One table with the difficulity of the question One table with the category of the question However, what do I do with the answers? Have them as seperate columns in the question-table? It sounds like a bad practice.(Also, where do I have the correct answer) Each question will have 5 answers where only one of them is correct.

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• No Hibernate Exception on the same insert of data

  - by Mark Estrada

  Hi All, Hibernate Newbie here. I am quite unsure why I am not getting any exception when I am executing below code. On first attempt, this code creates the Book Entry on my Book Table. But my concern is that when I execute below code again, no error was pop out by Hibernate. I was in fact expecting some sort of Violation of Primary Key Constraints as what I have bee doing in JDBC code. public class BookDao { public void createBook(Book bookObj) { Session session = HibernateUtil.getSessionFactory() .getCurrentSession(); session.beginTransaction(); session.saveOrUpdate(bookObj); session.getTransaction().commit(); } } public class HibernateUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() { try { // Create the SessionFactory from hibernate.cfg.xml return new AnnotationConfiguration().configure() .buildSessionFactory(); } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed ex.printStackTrace(); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } public class BookDBStarter { public static void main(String[] args) { Book bookHF = new Book(); bookHF.setIsbn("HF-12345"); bookHF.setName("Head First HTML"); bookHF.setPublishDate(new Date()); BookDao daoBook = new BookDao(); daoBook.createBook(bookHF); } } Is this normal hibernate way? And how will I know if my insert is successful? Any thoughts?

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• NHibernate Many to Many delete all my data in the table

  - by Daoming Yang

  I would love to thank @Stefan Steinegger and @David helped me out yesterday with many-to-many mapping. I have 3 tables which are "News", "Tags" and "News_Tags" with Many-To-Many relationship and the "News_Tags" is the link table. If I delete one of the news records, the following mappings will delete all my news records which have the same tags. One thing I need to notice, I only allowed unique tag stored in the "Tag" table. This mapping make sense for me, it will delete the tag and related News records, but how can I implement a tagging system with NHibernate? Can anyone give me some suggestion? Many thanks. Daoming. News Mapping: <class name="New" table="News" lazy="false"> <id name="NewID"> <generator class="identity" /> </id> <property name="Title" type="String"></property> <property name="Description" type="String"></property> <set name="TagsList" table="New_Tags" lazy="false" inverse="true" cascade="all"> <key column="NewID" /> <many-to-many class="Tag" column="TagID" /> </set> </class> Tag Mapping: <class name="Tag" table="Tags" lazy="false"> <id name="TagID"> <generator class="identity" /> </id> <property name="TagName" type="String"></property> <property name="DateCreated" type="DateTime"></property> <!--inverse="true" has been defined in the "News mapping"--> <set name="NewsList" table="New_Tags" lazy="false" cascade="all"> <key column="TagID" /> <many-to-many class="New" column="NewID" /> </set> </class>

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• JSON DATA formatting in WebAPI

  - by user1736299

  public class CalendarController : ApiController { Events[] events = new Events[] { new Events { title= "event1", start = System.DateTime.UtcNow, end = System.DateTime.UtcNow }, new Events { title= "event2", start = System.DateTime.UtcNow, end = System.DateTime.UtcNow }, new Events { title= "event3", start = System.DateTime.UtcNow, end = System.DateTime.UtcNow} }; public IEnumerable<Events> GetAllCalendar() { return events; } The JSON result for the above is [{ "title": "event1", "start": "2012-12-05T22:52:35.6471712Z", "end": "2012-12-05T22:52:35.6471712Z"}, { "title": "event2", "start": "2012-12-05T22:52:35.6471712Z", "end": "2012-12-05T22:52:35.6471712Z"}, { "title": "event3", "start": "2012-12-05T22:52:35.6471712Z", "end": "2012-12-05T22:52:35.6471712Z" }]? How to create the same JSON result without the double quotes but single quote. How to get the date in the format of ‘YYYY-MM-DD HH:MM:SS’ Thank you, Smith

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• WinForms / .Net interactive world map - how?

  - by FerretallicA

  In a CD collection program, I have each artist's country of origin stored in the main database and want to display a map of the world which: Colour-codes each country depending on the number of CDs by artists in that country Allows clicking on each country to filter a list of CDs to only ones by artists in that country This is a heavily simplified version of what I'm trying to do, but if I can at least get this far the rest should be easy enough to figure out. So far the closest thing I've found to what I'm trying to do is here: http://www.synergetechsolutions.com/blog/analytics-world-map-control Ideally I don't want to be embedding Flash in my program though, and the only other solutions I've found all involve SVG which I haven't managed to get working in practice outside of a web browser control (and I DEFINITELY don't want to be embedding a browser in the forms). Something in pure managed code and either GDI+ or WPF would be preferable. Are there any existing components that would get me started, or can anyone suggest how to approach it from scratch?

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• php/mysql show data from chosen checkboxes

  - by Michael

  Hi. I have a table called FRUIT id type daysold 1 banana 5 2 apple 6 3 apple 4 4 peach 2 5 banana 6 What I would like is to have 3 checkboxes: Banana [ ] Apple [ ] Peach [ ] SUBMIT Then if I've only checked "Banana" and "Peach" the mysql output should only show me the rows that matches those two types. And the checkboxes should remain checked to highlight what was chosen. I can make the checkboxes but then that's about it really. I don't know how to properly get the info from the checkboxes and down to the WHERE argument in the MYSQL-code. Especially not with two types chosen. If it was just a dropdown menu with a single choice then I'd add the choice to the url and put WHERE type='$choice' - but I'm struggling with the multiple choices. I'm a bit of a novice at both php and mysql, so I'm a bit lost on this one.

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• How to handle choice field with JPA 2, Hibernate 3.5

  - by phmr

  I have an entity with Integer attributes that looks like this in proto code: class MyEntity: String name Integer frequency Integer type def getFrequency() def getType() get* accessors return strings according to this table. value(type) HumanReadableString(type) 1 BSD 2 Apache 3 GPL min frequency max frequency HumanReadableString(frequency) 0 1000 rare 1000 2000 frequent 2001 3000 sexy It should be possible to get all possible values that an attribute can take, example: getChoices(MyEntity, "type") returns ("rare", "frequent", "sexy") It should be possible to get the bound value from the string: getValue(MyEntity, "frequency", "sexy") returns (2000,3000)

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• querying larg text file containing JSON objects.

  - by Maciek Sawicki

  Hi, I have few Gigabytes text file in format: {"user_ip":"x.x.x.x", "action_type":"xxx", "action_data":{"some_key":"some_value"...},...} each entry is one line. First I would like to easily find entries for given ip. This part is easy because I can use grep for example. However even for this I would like to find better solution because I would like to get response as fast as possible. Next part is more complicated because I would like to find entries from selected ip and of selected type and with particular value of some_key in action_data. Probably I would have to convert this file to SQL db (probably SQLite, because it will be desktop APP), but I would ask if there are exists better solutions?

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• Data table multiple row selection

  - by Hari kanna

  i am a small time web develper i am working on JSF project i am a front end designer and also interested in JSF i try 2 solve this issue in web app... k my question is here... i have a datatable with checkbox i want 2 select multiple row selection with css background color....

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• Storing records in a dropdownlist from DB without using LINQ Data source

  - by user1318369

  I have a website for dance academy where Users can register and add/drop dance classes. In the web page to drop a particular dance, for a particular user, the dropdown displays her registered dances. Now I want to delete one of the dances from the list. So i'll remove the row from the table and also from the dropdownlist. The problem is that everytime the item with the lowest ID (index) is getting deleted, no matter which one the user selects. I think I am storing the DataTextField and DataValueField for the dropdown incorrectly. Can someone please help me out? The code is: private void PopulateDanceDropDown() { var registereddanceList = from dd in context.DANCER_AND_DANCE where dd.UserId == dancerId select new { Text = dd.DanceName, Value = dd.DanceId }; dances.DataSource = registereddanceList; dances.DataTextField = "Text"; dances.DataValueField = "Value"; dances.DataBind(); } protected void dropthedance(object o, EventArgs e) { String strDataValueField = dances.SelectedItem.Value; int danceIDFromDropDown = Convert.ToInt32(strDataValueField); var dancer_dance = from dd in context.DANCER_AND_DANCE where dd.DanceId == danceIDFromDropDown select dd; foreach (var dndd in dancer_dance) { context.DANCER_AND_DANCE.DeleteOnSubmit(dndd); } try { context.SubmitChanges(); } catch (Exception ex) { Console.WriteLine(ex); } PopulateDanceDropDown(); }

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• JSF Open new window and display bean data

  - by JSFPRINTER

  I am running JSF 2.0 and the latest version of Primefaces 2.2RC1 I believe. I am trying to create a printer friendly window. When the user clicks on a p:commandLink I want a new window to open and display a xhtml file I have named printView.xhtml. Now I can get the window working fine using JavaScript window.open but when I open the new window it will not render any values it just displays everything as #{myBean.value}. Does anyone know how to properly open a window and extend the current scope of the application into that window so I can call all of my managed beans properly and display the values etc. etc.

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• C: getopt with list of acceptable optarg. What is the best practise ?

  - by Xavier Maillard

  Hi, I am writing a C program which is a frontend to a myriad tools. This fronted will be launched like this: my-frontend --action <AN ACTION> As all the tools have the same prefix, let say for this example this prefix is "foo". I want to concatenate "AN ACTION" to this prefix and exec this (if the tool exists). I have written something but my implementation uses strcmp to test that "AN ACTION" is a valid action. Even if this works, I do not like it. So I am looking for a nicer solution that would do the same. The list of possibilities is pretty small (less than 10) and static (the list is "hardcoded") but I am sure there is a more "C-ish" way to do this (using a struct or something like that). As I am not a C expert, I am asking for your help. Regards

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• Is there anything like a generic list in Cocoa / Objective-C?

  - by Holli

  What I really like in C# are generic lists. A list that can contain only one type of objects. Is there something like a generic list in Cocoa/Objective-C? As far I only know NSArray who will take a pointer to any object.

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• Efficient storage/retrieval method for replayable comet style applications (Google Wave, Etherpad)

  - by Gareth Simpson

  I am considering a web application that would have the same kind of multi user, automatic saving, infinite undo / replay capabilities that you see in Google Wave and Etherpad (albeit on a drastically smaller scale and userbase). Before I go away and reinvent the wheel, is this something that has already been addressed as either a piece of technology or library, or even just a design pattern. I know this isn't necessarily the best Stack Overflow question as there is probably not a "right" answer, but my Google-fu has failed me and I'd just like a reading list! Ordinarily I would be developing under python/django but this is not a firm requirement just a preference :)

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• Create multiple TCP Connections in C# then wait for data

  - by Ryan French

  Hi Everyone, I am currently creating a Windows Service that will create TCP connections to multiple machines (same socket on all machines) and then listen for 'events' from those machines. I am attempting to write the code to create a connection and then spawn a thread that listens to the connection waiting for packets from the machine, then decode the packets that come through, and call a function depending on the payload of the packet. The problem is I'm not entirely sure how to do that in C#. Does anyone have any helpful suggestions or links that might help me do this? Thanks in advance for any help!

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• Cakephp, Retreive Data for HABTM Models using find

  - by user298079

  I am new to cakephp and I'm trying to accomplish something that should be relatively easy. I have 2 models projects & categories bind by HABTM relationship. I am trying to perform the following query - find all projects that belong to a category $projects = $this->Project->find('all', array('conditions' => array('Category.slug' => $category))); However when I'm doing so it generates an SQL error: SQL Error: 1054: Unknown column 'Category.slug' in 'where clause' What am I doing wrong??

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• creative way for implementing Data object with its corresponding business logic class in java

  - by ekeren

  I have a class that need to be serialized (for both persistentcy and client-server communication) for simplicity's sake let's call the classes Business a BusinessData and I prefix for their Interfaces. All the getter and setter are delegated from Business class to BusinessData class. I thought about implementing IBusinessData interface that will contain all the getter and setters and IBusiness interface that will extend it. I can either make Business extend BuisnessData so I will not need to implement all getter and setter delegates, or make some abstract class ForwardingBusinessData that will only delegate getter and setters. Any of the above option I lose my hierarchy freedom, do any of you have any creative solutions for this problem... I also reviewed DAO pattern: http://java.sun.com/blueprints/patterns/DAO.html

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• array of structures, or structure of arrays?

  - by Jason S

  Hmmm. I have a table which is an array of structures I need to store in Java. The naive don't-worry-about-memory approach says do this: public class Record { final private int field1; final private int field2; final private long field3; /* constructor & accessors here */ } List<Record> records = new ArrayList<Record>(); If I end up using a large number ( 106 ) of records, where individual records are accessed occasionally, one at a time, how would I figure out how the preceding approach (an ArrayList) would compare with an optimized approach for storage costs: public class OptimizedRecordStore { final private int[] field1; final private int[] field2; final private long[] field3; Record getRecord(int i) { return new Record(field1[i],field2[i],field3[i]); } /* constructor and other accessors & methods */ } edit: assume the # of records is something that is changed infrequently or never I'm probably not going to use the OptimizedRecordStore approach, but I want to understand the storage cost issue so I can make that decision with confidence. obviously if I add/change the # of records in the OptimizedRecordStore approach above, I either have to replace the whole object with a new one, or remove the "final" keyword. kd304 brings up a good point that was in the back of my mind. In other situations similar to this, I need column access on the records, e.g. if field1 and field2 are "time" and "position", and it's important for me to get those values as an array for use with MATLAB, so I can graph/analyze them efficiently.

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• Encapsulating user input of data for a class (C++)

  - by Dr. Monkey

  For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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• Multiple Actions (Forms) on one Page - How not to lose master data, after editing detail data?

  - by nWorx

  Hello all, I've got a form where users can edit members of a group. So they have the possibilty to add members or remove existing members. So the Url goes like ".../Group/Edit/4" Where 4 is the id of the group. the view looks like this <% using (Html.BeginForm("AddUser", "Group")) %> <%{%> <label for="newUser">User</label> <%=Html.TextBox("username")%> <input type="submit" value="Add"/> </div> <%}%> <% using (Html.BeginForm("RemoveUser", "Group")) %> <%{%> <div class="inputItem"> <label for="groupMember">Bestehende Mitglieder</label> <%= Html.ListBox("groupMember", from g in Model.GetMembers() select new SelectListItem(){Text = g}) %> <input type="submit" value="Remove" /> </div> <%}%> The problem is that after adding or removing one user i lose the id of the group. What is the best solution for solving this kind of problem? Should I use hidden fields to save the group id? Thanks in advance.

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• Data not synchornizing java sockets

  - by Droid_Interceptor

  I am writing a auction server and client and using a class called BidHandler to deal with the bids another class AuctionItem to deal with the items for auction. The main problem I am having is little synchroization problem. Screen output of client server as can see from the image at 1st it takes the new bid and changes the value of the time to it, but when one the user enters 1.0 the item seems to be changed to that. But later on when the bid changes again to 15.0 it seems to stay at that price. Is there any reason for that. I have included my code below. Sorry if didnt explain this well. This is the auction client import java.io.*; import java.net.*; public class AuctionClient { private AuctionGui gui; private Socket socket; private DataInputStream dataIn; private DataOutputStream dataOut; //Auction Client constructor String name used as identifier for each client to allow server to pick the winning bidder public AuctionClient(String name,String server, int port) { gui = new AuctionGui("Bidomatic 5000"); gui.input.addKeyListener (new EnterListener(this,gui)); gui.addWindowListener(new ExitListener(this)); try { socket = new Socket(server, port); dataIn = new DataInputStream(socket.getInputStream()); dataOut = new DataOutputStream(socket.getOutputStream()); dataOut.writeUTF(name); while (true) { gui.output.append("\n"+dataIn.readUTF()); } } catch (Exception e) { e.printStackTrace(); } } public void sentBid(String bid) { try { dataOut.writeUTF(bid); } catch(IOException e) { e.printStackTrace(); } } public void disconnect() { try { socket.close(); } catch(IOException e) { e.printStackTrace(); } } public static void main (String args[]) throws IOException { if(args.length!=3) { throw new RuntimeException ("Syntax: java AuctionClient <name> <serverhost> <port>"); } int port = Integer.parseInt(args[2]); AuctionClient a = new AuctionClient(args[0],args[1],port); } } The Auction Server import java.io.*; import java.net.*; import java.util.*; public class AuctionServer { public AuctionServer(int port) throws IOException { ServerSocket server = new ServerSocket(port); while(true) { Socket client = server.accept(); DataInputStream in = new DataInputStream(client.getInputStream()); String name = in.readUTF(); System.out.println("New client "+name+" from " +client.getInetAddress()); BidHandler b = new BidHandler (name, client); b.start(); } } public static void main(String args[]) throws IOException { if(args.length != 1) throw new RuntimeException("Syntax: java AuctionServer <port>"); new AuctionServer(Integer.parseInt(args[0])); } } The BidHandler import java.net.*; import java.io.*; import java.util.*; import java.lang.Float; public class BidHandler extends Thread { Socket socket; DataInputStream in; DataOutputStream out; String name; float currentBid = 0.0f; AuctionItem paper = new AuctionItem(" News Paper ", " Free newspaper from 1990 ", 1.0f, false); protected static Vector handlers = new Vector(); public BidHandler(String name, Socket socket) throws IOException { this.name = name; this.socket = socket; in = new DataInputStream (new BufferedInputStream (socket.getInputStream())); out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream())); } public synchronized void run() { try { broadcast("New bidder has entered the room"); handlers.addElement(this); while(true) { broadcast(paper.getName() + paper.getDescription()+" for sale at: " +paper.getPrice()); while(paper.getStatus() == false) { String message = in.readUTF(); currentBid = Float.parseFloat(message); broadcast("Bidder entered " +currentBid); if(currentBid > paper.getPrice()) { paper.setPrice(currentBid); broadcast("New Higgest Bid is "+paper.getPrice()); } else if(currentBid < paper.getPrice()) { broadcast("Higgest Bid is "+paper.getPrice()); } else if(currentBid == paper.getPrice()) { broadcast("Higgest Bid is "+paper.getPrice()); } } } } catch(IOException ex) { System.out.println("-- Connection to user lost."); } finally { handlers.removeElement(this); broadcast(name+" left"); try { socket.close(); } catch(IOException ex) { System.out.println("-- Socket to user already closed ?"); } } } protected static void broadcast (String message) { synchronized(handlers) { Enumeration e = handlers.elements(); while(e.hasMoreElements()) { BidHandler handler = (BidHandler) e.nextElement(); try { handler.out.writeUTF(message); handler.out.flush(); } catch(IOException ex) { handler = null; } } } } } The AuctionItem Class class AuctionItem { String itemName; String itemDescription; float itemPrice; boolean itemStatus; //Create a new auction item with name, description, price and status public AuctionItem(String name, String description, float price, boolean status) { itemName = name; itemDescription = description; itemPrice = price; itemStatus = status; } //return the price of the item. public synchronized float getPrice() { return itemPrice; } //Set the price of the item. public synchronized void setPrice(float newPrice) { itemPrice = newPrice; } //Get the status of the item public synchronized boolean getStatus() { return itemStatus; } //Set the status of the item public synchronized void setStatus(boolean newStatus) { itemStatus = newStatus; } //Get the name of the item public String getName() { return itemName; } //Get the description of the item public String getDescription() { return itemDescription; } } There is also simple GUI to go with this that seems to be working fine. If anyone wants it will include the GUI code.

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• String or binary data would be truncated -- Heisenberg problem

  - by harpo

  When you get this error, the first thing you ask is, which column? Unfortunately, SQL Server is no help here. So you start doing trial and error. Well, right now I have a statement like: INSERT tbl (A, B, C, D, E, F, G) SELECT A, B * 2, C, D, E, q.F, G FROM tbl ,othertable q WHERE etc etc Note that Some values are modified or linked in from another table, but most values are coming from the original table, so they can't really cause truncation going back to the same field (that I know of). Eliminating fields one at a time eventually makes the error go away, if I do it cumulatively, but — and here's the kicker — it doesn't matter which fields I eliminate. It's as if SQL Server is objecting to the total length of the row, which I doubt, since there are only about 40 fields in all, and nothing large. Anyone ever seen this before? Thanks. UPDATE: I have also done "horizontal" testing, by filtering out the SELECT, with much the same result. In other words, if I say WHERE id BETWEEN 1 AND 100: Error WHERE id BETWEEN 1 AND 50: No error WHERE id BETWEEN 50 AND 100: No error I tried many combinations, and it cannot be limited to a single row.

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• hibernate not throwing stale state exception nor it is overwriting data

  - by Reddy

  Our application do the following. 1. Start the transaction. 2. Execute a query using prepared statement 3. Check a condition to see the number of rows updated are equal to the required number. 4. It commits on success of above condition otherwise it will roll back However the problem is that when two threads are simultaneously enter this code. Thread-1 is updating a row in step 2. It checked the condition and committed successfully since the condition is successful. Thread-2 started execution somewhere between steps 1 & 4, and it is failing on at condition checking at step 3 (as it is getting number of updated rows as 0). I expected second thread to throw an exception but it is not. What could be the problem?

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• get data from asp page

  - by sam

  I am wondering if there is anyway to grab the html that is generated from an ASP page. I am trying to pull a table from the page, and I foolishly used a static html page so I would not have to be constantly querying the server where this page resides while I tested out my code. The javascript code I wrote to grab to unlabeled table from the page works. Then when I put it into practice with the real page and found that the ASP page does not generate a viewable page with a jquery .get request on the URL. Is there any way to query the page for the table I need so that the ASP page returns a valid page on request? (I am also limited to using javascript and perl for this, the server where this will reside will not run php and I have no desire to learn ASP.NET to solve this by adding to the issue of proprietary software)

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• Group MySQL Data into Arbitrarily Sized Time Buckets

  - by Eric J.

  How do I count the number of records in a MySQL table based on a timestamp column per unit of time where the unit of time is arbitrary? Specifically, I want to count how many record's timestamps fell into 15 minute buckets during a given interval. I understand how to do this in buckets of 1 second, 1 minute, 1 hour, 1 day etc. using MySQL date functions, e.g. SELECT YEAR(datefield) Y, MONTH(datefield) M, DAY(datefield) D, COUNT(*) Cnt FROM mytable GROUP BY YEAR(datefield), MONTH(datefield), DAY(datefield) but how can I group by 15 minute buckets?

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