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  • Am I understanding premature optimization correctly?

    - by Ed Mazur
    I've been struggling with an application I'm writing and I think I'm beginning to see that my problem is premature optimization. The perfectionist side of me wants to make everything optimal and perfect the first time through, but I'm finding this is complicating the design quite a bit. Instead of writing small, testable functions that do one simple thing well, I'm leaning towards cramming in as much functionality as possible in order to be more efficient. For example, I'm avoiding multiple trips to the database for the same piece of information at the cost of my code becoming more complex. One part of me wants to just not worry about redundant database calls. It would make it easier to write correct code and the amount of data being fetched is small anyway. The other part of me feels very dirty and unclean doing this. :-) I'm leaning towards just going to the database multiple times, which I think is the right move here. It's more important that I finish the project and I feel like I'm getting hung up because of optimizations like this. My question is: is this the right strategy to be using when avoiding premature optimization?

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  • How to keep form items selected after post request?

    - by Ole Jak
    I have a simple html form. On php page. A simple list is placed on form. I submit this form (selected list items) to this page so it gives me page refresh. I want items which were POSTED to be selected after form was submited. How to do such thing? For my form I use such code: <form action="FormPage.php" method="post"> <select id="Streams" class="multiselect ui-widget-content ui-corner-all" multiple="multiple" name="Streams[]"> <?php $query = " SELECT s.streamId, s.userId, u.username FROM streams AS s JOIN user AS u ON s.userId = u.id LIMIT 0 , 30 "; $streams_set = mysql_query($query, $connection); confirm_query($streams_set); $streams_count = mysql_num_rows($streams_set); while ($row = mysql_fetch_array($streams_set)){ echo '<option value="' , $row['streamId'] , '"> ' , $row['username'] , ' (' , $row['streamId'] ,')' ,'</option> '; } ?> </select> <br/> <input type="submit" class="ui-state-default ui-corner-all" name="submitForm" id="submitForm" value="Play Stream from selected URL's!"/> </fieldset> </form>

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  • Using JQuery in an AJAX control and avoiding conflicts

    - by Rich Andrews
    Hi, I am using JQuery within a custom AJAX user control (part of a home grown toolkit) and I need to ensure that JQuery is present on the hosting page. There can be multiple instances of the control on a page and some controls may need to use different versions of JQuery. At the moment I am using the following code to load in JQuery when the control initializes... Page.ClientScript.RegisterClientScriptInclude(Page.GetType(), "jquery-1.4.4.min.js", this.ResolveUrl("TextControlPlugin/lib/jquery-1.4.4.min.js")); This works because the scriptmanager handles not putting multiple copies of the same script into he page. Problems... I cannot use JQuery statically in the calling page (I may not have a control on the page but need to use JQuery) The scriptmanager appears to handle only duplicate URL's and I will need to deploy it from potentially 2 different URL's (the calling page's copy and the controls copy) So, is there a way to isolate a version of JQuery to the context of my control that doesnt interfear with any use of JQuery from the calling page? The developer writing the page may not have access to the internals of the control. I have looked at JQuery.noConflict() but cannot seem to get it to work correctly - I believe I'm having problems with the order in which the scripts are injected into the page - I keep getting JQuery is undefined errors. Any help would be much appreciated

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  • How do I handle the messages for a simple web-based live chat, on the server side?

    - by Carson Myers
    I'm building a simple live chat into a web application running on Django, but one thing I'm confused about is how I should store the messages between users. The chat will support multiple users, and a chat "session" is composed of users connected to one user that is the "host." The application is a sort of online document collaboration thing, so user X has a document, and users Y and Z would connect to user X to talk about the document, and that would be one chat session. If user Y disconnected for five minutes, and then signed back in and reconnected to user X, he should not get any of the messages shared between users X and Z while he was away. if users X, Y, and Z can have a chat session about user X's document, then users X and Y can connect to a simultaneous, but separate discussion about user Z's document. How should I handle this? Should I keep each message in the database? Each message would have an owner user and a target user (the host), and a separate table would be used to connect users with messages (which messages are visible to what users). Or should I store each session as an HTML file on the server, which messages get appended to? The problem is, I can't just send messages directly between clients. They have to be sent to the server in a POST request, and then each client has to periodically check for the messages in a GET request. Except I can't just have each message cleared after a client fetches it, because there could be multiple clients. How should I set this up? Any suggestions?

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  • How to write automated tests for SQL queries?

    - by James
    The current system we are adopting at work is to write some extremely complex queries which perform multiple calculations and have multiple joins / sub-queries. I don't think I am experienced enough to say if this is correct or not so I am agreeing and attempting to function with this system as it has clear benefits. The problem we are having at the moment is that the person writing the queries makes a lot of mistakes and assumes everything is correct. We have now assigned a tester to analyse all of the queries but this still proves extremely time consuming and stressful. I would like to know how we could create an automated procedure (without specifically writing it with code if possible as I can work out how to do that the long way) to verify a set of 10+ different inputs, verify the output data and say if the calculations are correct. I know I could write a script using specific data in the database and create a script using c# (the db is SQL Server) and verify all the values coming out but I would like to know what the official "standard" is as my experience is lacking in this area and I would like to improve. I am happy to add more information if required, add a comment if necessary. Thank you. Edit: I am using c#

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  • Database schema for a library

    - by ABach
    Hi all - I'm designing a library management system for a department at my university and I wanted to enlist your eyes on my proposed schema. This post is primarily concerned with how we store multiple copies of each book; something about what I've designed rubs me the wrong way, and I'm hoping you all can point out better ways to tackle things. For dealing with users checking out books, I've devised three tables: book, customer, and book_copy. The relationships between these tables are as follows: Every book has many book_copies (to avoid duplicating the book's information while storing the fact that we have multiple copies of that book). Every user has many book_copies (the other end of the relationship) The tables themselves are designed like this: ------------------------------------------------ book ------------------------------------------------ + id + title + author + isbn + etc. ------------------------------------------------ ------------------------------------------------ customer ------------------------------------------------ + id + first_name + first_name + email + address + city + state + zip + etc. ------------------------------------------------ ------------------------------------------------ book_copy ------------------------------------------------ + id + book_id (FK to book) + customer_id (FK to customer) + checked_out + due_date + etc. ------------------------------------------------ Something about this seems incorrect (or at least inefficient to me) - the perfectionist in me feels like I'm not normalizing this data correctly. What say ye? Is there a better, more effective way to design this schema? Thanks!

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  • NSNotification vs. Delegate Protocols?

    - by jr
    I have an iPhone application which basically is getting information from an API (in XML, but maybe JSON eventually). The result objects are typically displayed in view controllers (tables mainly). Here is the architecture right now. I have NSOperation classes which fetch the different objects from the remote server. Each of these NSOperation classes, will take a custom delegate method which will fire back the resulting objects as they are parsed, and then finally a method when no more results are available. So, the protocol for the delegates will be something like: (void) ObjectTypeResult:(ObjectType *)result; (void) ObjectTypeNoMoreResults; I think the solution works well, but I do end up with a bunch of delegate protocols around and then my view controllers have to implement all these delegate methods. I don't think its that bad, but I'm always on the lookout for a better design. So, I'm thinking about using NSNotifications to remove the use of the delegates. I could include the object in the userInfo part of the notification and just post objects as received, and then a final event when no more are available. Then I could just have one method in each view controller to receive all the data, even when using multiple objects in one controller.† So, can someone share with me some pros/cons of each approach. Should I consider refactoring my code to use Events rather then the delegates? Is one better then the other in certain situations? In my scenario I'm really not looking to receive notifications in multiple places, so maybe the protocol based delegates are the way to go. Thanks!

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  • Use MySQL trigger to update another table when duplicate key found

    - by Jason
    Been scratching my head on this one, hoping one of you kind people and direct me towards solving this problem. I have a mysql table of customers, it contains a lot of data, but for the purpose of this question, we only need to worry about 4 columns 'ID', 'Firstname', 'Lastname', 'Postcode' Problem is, the table contains a lot of duplicated customers. A new table is being created where each customer is unique and for us, we decide a unique customer is based on 'Firstname', 'Lastname' and 'Postcode' However, (this is the important bit) we need to ensure each new "unique" customer record also can be matched to the original multiple entries of that customer in the original table. I believe the best way to do this is to have a third table, that has 'NewUniqueID', 'OldCustomerID'. So we can search this table for 'NewUniqueID' = '123' and it would return multiple 'OldCustomerID' values where appropriate. I am hoping to make this work using a trigger and the on duplicate key syntax. So what would happen is as follows: An query is run taking the old customer table and inserting it in to the new unique table. (A standard Insert Select query) On duplicate key continue adding records, but add one entry in to the third table noting the 'NewUniqueID' that duped along with the 'OldCustomerID' of the record we were trying to insert. Hope this makes sense, my apologies if it isn't clear. I welcome and appreciate any thoughts on this one! Many thanks Jason

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  • How to use named_scope to incrementally construct a complex query?

    - by wbharding
    I want to use Rails named_scope to incrementally build complex queries that are returned from external methods. I believe I can get the behavior I want with anonymous scopes like so: def filter_turkeys Farm.scoped(:conditions => {:animal => 'turkey'}) end def filter_tasty Farm.scoped(:conditions => {:tasty => true}) end turkeys = filter_turkeys is_tasty = filter_tasty tasty_turkeys = filter_turkeys.filter_tasty But say that I already have a named_scope that does what these anonymous scopes do, can I just use that, rather than having to declare anonymous scopes? Obviously one solution would be to pass my growing query to each of the filter methods, a la def filter_turkey(existing_query) existing_query.turkey # turkey is a named_scoped that filters for turkey end But that feels like an un-DRY way to solve the problem. Oh, and if you're wondering why I would want to return named_scope pieces from methods, rather than just build all the named scopes I need and concatenate them together, it's because my queries are too complex to be nicely handled with named_scopes themselves, and the queries get used in multiple places, so I don't want to manually build the same big hairy concatenation multiple times.

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  • Jetty 7 will not allow me to customize a session cookie path

    - by Bob Obringer
    Using Jetty 7.0.2, I am unable to set a custom session cookie path. I am hosting multiple sites on the same server using apache to proxy requests to the proper context. (replaced http as htp as stackoverflow thinks my multiple links might be spam) <VirtualHost *:80> ServerName context.domain.com ProxyRequests On ProxyPreserveHost Off <Proxy *:80> Order deny,allow Allow from 127.0.0.1 </Proxy> ProxyPass / htp://localhost:8080/context/ ProxyPassReverse / htp://localhost:8080/context/ <Location /> Order allow,deny Allow from all </Location> </VirtualHost> Jetty is running on the same server on port 8080 and my context is available @ /context The user accesses the application @ htp://context.domain.com but jetty is setting the path for the session cookie @ /context. This prevents the browser from accessing the cookie since the the actual path to the context is not being used. I need to override Jetty's default setting to set the cookie for the context, and set the path at the root ( / ). In my Jetty's webdefault.xml I have the following, which is partially working: <context-param> <param-name>org.eclipse.jetty.servlet.SessionCookie</param-name> <param-value>CustomCookieName</param-value> </context-param> <context-param> <param-name>org.eclipse.jetty.servlet.SessionPath</param-name> <param-value>/</param-value> </context-param> The cookie is properly set with a custom name, but it is NOT setting the SessionPath. No matter what I set the value to... it refuses to set a cookie at any path but /context. This has been driving me crazy so any help would be greatly appreciated.

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  • MEF instance management

    - by Lawrence A. Contreras
    I am working on application that has multiple modules and sub modules. Here's what I need to do: ModuleA has a sub module SubModuleA, SubModuleB, SubModuleC. I want to export ModuleA, SubModuleA, SubModuleB, SubModuleC. ModuleA can have multiple instances. Whenever I import ModuleA inside the sub modules, I want to get the correct instance and also when I import SubModuleA,SubModuleB and SubModuleC inside other classes. How can I manage that scenario using MEF? Do I really need to use MEF. Updated: Here's a quick example: public class School { List<Classroom> classRooms { get; set; } } [Export] public class Classroom { List<Teacher> teachers { get; set; } } public class Teacher { List<Student> students { get; set; } } public class Student { [Import] Classroom classroom { get; set; } } As you can see, I want to export the classroom class because I need to import it in the Student class, let's just say that I really need the classroom class inside the student class. I want to skip the part where we pass the classroom to the teacher and from the teacher we'll pass it to the student. But when I import classroom, I want to have the correct instance where that class room contains the teacher of the student.

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  • merge my code with Ajax code>>> problem

    - by sandy
    I want to help me In the following link i found nice code in Ajax http://www.w3schools.com/php/php_ajax_livesearch.asp I want to link my code with the code you see in the link above and replace dropdown list How can I do it for I could not where is it change in code even my code work as Ajax ?? I wish .... I wish .... I wish any somebody can help me <?php include ("connect.php"); print_r($_POST['sector_list']); $member_id = intval($_POST['sector_list']); if($member_id == 0) { // Default choice was selected } else { $res = mysql_query("SELECT * FROM members WHERE MemberID = $member_id LIMIT 1"); if(mysql_num_rows($res) == 0) { // Not a valid member } else { // The member is in the database } } ?> <form method="POST" action=<?php echo $_SERVER["PHP_SELF"]; ?> > <input type="hidden" name="sector" value="sector_list"> <select name="sector_list[]" class="inputstandard" multiple="multiple"> <option size ="40" value="default">send to </option> <?php $result = mysql_query('SELECT * from members') or die(mysql_error()); while ($row = mysql_fetch_assoc($result)) { echo '<option value="' . $row['MemberName'] . '">' . $row['MemberName']. '</option>'; } ?> <input type ="submit" name ="go" value = "go" > </select> </form>

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  • Select return dynamic columns

    - by Ascalonian
    I have two tables: Standards and Service Offerings. A Standard can have multiple Service Offerings. Each Standard can have a different number of Service Offerings associated to it. What I need to be able to do is write a view that will return some common data and then list the service offerings on one line. For example: Standard Id | Description | SO #1 | SO #2 | SO #3 | ... | SO #21 | SO Count 1 | One | A | B | C | ... | G | 21 2 | Two | A | | | ... | | 1 3 | Three | B | D | E | ... | | 3 I have no idea how to write this. The number of SO columns is set to a specific number (21 in this case), so we cannot exceed past that. Any ideas on how to approach this? A place I started is below. It just returned multiple rows for each Service Offering, when they need to be on one row. SELECT * FROM SERVICE_OFFERINGS WHERE STANDARD_KEY IN (SELECT STANDARD_KEY FROM STANDARDS)

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  • Questions about the Backpropogation Algorithm

    - by Colemangrill
    I have a few questions concerning backpropogation. I'm trying to learn the fundamentals behind neural network theory and wanted to start small, building a simple XOR classifier. I've read a lot of articles and skimmed multiple textbooks - but I can't seem to teach this thing the pattern for XOR. Firstly, I am unclear about the learning model for backpropogation. Here is some pseudo-code to represent how I am trying to train the network. [Lets assume my network is setup properly (ie: multiple inputs connect to a hidden layer connect to an output layer and all wired up properly)]. SET guess = getNetworkOutput() // Note this is using a sigmoid activation function. SET error = desiredOutput - guess SET delta = learningConstant * error * sigmoidDerivative(guess) For Each Node in inputNodes For Each Weight in inputNodes[n] inputNodes[n].weight[j] += delta; // At this point, I am assuming the first layer has been trained. // Then I recurse a similar function over the hidden layer and output layer. // The prime difference being that it further divi's up the adjustment delta. I realize this is probably not enough to go off of, and I will gladly expound on any part of my implementation. Using the above algorithm, my neural network does get trained, kind of. But not properly. The output is always XOR 1 1 [smallest number] XOR 0 0 [largest number] XOR 1 0 [medium number] XOR 0 1 [medium number] I can never train the [1,1] [0,0] to be the same value. If you have any suggestions, additional resources, articles, blogs, etc for me to look at I am very interested in learning more about this topic. Thank you for your assistance, I appreciate it greatly!

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  • implementing a Intelligent File Transfer Software in java over TCP/IP

    - by whyjava
    Hello I am working on a proposal where we have to implement a software which can move files between one source to destination.The overall goal of this project is to create intelligent file transfer.This software will have three components :- 1) Broker : Broker is the module that communicates with other brokers, monitors files, moves files, retrieves configurations from the Configuration Manager, supplies process information for the monitor, archives files, writes all process data to log files and escalates issues if necessary 2) Configuration Manager :Configuration Manager is a web-based application used to configure and deploy the configuration to all brokers. 3) Monitor : Monitor is a web-based application used to monitor each Broker in the environment. This project has to be built up in java and protocol for file transfer in tcp/ip. Client does not want to use FTP. File Transfer seems very easy, until there are several processes who are waiting to pick the file up automatically. Several problems arise: How can we guarantee the file is received at the destination? If a file isn’t received the first time, we should try it again (even after a restart or power breakdown) ? How does the receiver knows the file that is received is complete? How can we transfer multiple files synchronously? How can we protect the bandwidth, so file transfer isn’t blocking other processes? How does one interoperate between multiple OS platforms? What about authentication? How can we monitor het workflow? Auditing / logging Archiving Can you please provide answer to some of these? Thanks

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  • Should i write my own forum? If my site has banning/PM/etc?

    - by acidzombie24
    I built a site from scratch (already done). It has banning, PM, comments, etc. The PMs and comments are done using markdown (like SO system). Should i write my own forum code or should i find one already made? What are reasons for or against writing my own? There are pros and cons for writing my own or using another software. But some cons keeping me from using another forum software is Multiple Logins: One for the site, one for separate forums. Need to Customization code: I'll need to change the toolbar in the forum software so i can access pages on the regular site. Look consistency: It may look drastically different from my site even after applying lots of css changes. Banning and User consistency. Users may be ban on site or on forums but not the other. users may select a different or multiple usernames on the forum instead of being forced to use the same username on both site and forum. What are reasons for or against writing my own and using forum software?

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  • Symfony2 entity field type alternatives to "property" or "__toString()"?

    - by Polmonino
    Using Symfony2 entity field type one should specify property option: $builder->add('customers', 'entity', array( 'multiple' => true, 'class' => 'AcmeHelloBundle:Customer', 'property' => 'first', )); But sometimes this is not sufficient: think about two customers with the same name, so display the email (unique) would be mandatory. Another possibility is to implement __toString() into the model: class Customer { public $first, $last, $email; public function __toString() { return sprintf('%s %s (%s)', $this->first, $this->last, $this->email); } } The disadvances of the latter is that you are forced to display the entity the same way in all your forms. Is there any other way to make this more flexible? I mean something like a callback function: $builder->add('customers', 'entity', array( 'multiple' => true, 'class' => 'AcmeHelloBundle:Customer', 'property' => function($data) { return sprintf('%s %s (%s)', $data->first, $data->last, $data->email); }, ));

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  • cakephp hasMany through and multiselect form

    - by Zoran Kalinic
    I'm using cakephp 2.2.2 and I have a problem with the editing view Models and relationships are: Person hasMany OrganizationPerson Organization hasMany OrganizationPerson OrganizationPerson belongs to Person,Organization A basic hasMany through relationship as found within cake documentation. Tables are: people (id,...) organizations (id,...) organization_people (id, person_id,organization_id,...) In the person add and edit forms there is a select box allowing a user to select multiple organization. The problem I have is, when a user edits an existing person, the associated organizations aren't pre-selected. Here is the code in the PeopleController: $organizations = $this->Person->OrganizationPerson->Organization->find('list'); $this->set(compact('organizations')); Related part of the code in the People/edit code looks like: $this->Form->input('OrganizationPerson.organization_id', array('multiple' => true, 'empty' => false)); This will populate the select field, but it does not pre-select it with the Person's associated organizations. Format and content of the $this-data: Array ( [Person] => Array ( [id] => 1 ... ) [OrganizationPerson] => Array ( [0] => Array ( [id] => 1 [person_id] => 1 [organization_id] => 1 ... ) [1] => Array ( [id] => 2 [person_id] => 1 [organization_id] => 2 ... ) ) ) What I have to add/change in the code to get pre-selected organizations? Thanks in advance!

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  • Tree-like queues

    - by Rehno Lindeque
    I'm implementing a interpreter-like project for which I need a strange little scheduling queue. Since I'd like to try and avoid wheel-reinvention I was hoping someone could give me references to a similar structure or existing work. I know I can simply instantiate multiple queues as I go along, I'm just looking for some perspective by other people who might have better ideas than me ;) I envision that it might work something like this: The structure is a tree with a single root. You get a kind of "insert_iterator" to the root and then push elements onto it (e.g. a and b in the example below). However, at any point you can also split the iterator into multiple iterators, effectively creating branches. The branches cannot merge into a single queue again, but you can start popping elements from the front of the queue (again, using a kind of "visitor_iterator") until empty branches can be discarded (at your discretion). x -> y -> z a -> b -> { g -> h -> i -> j } f -> b Any ideas? Seems like a relatively simple structure to implement myself using a pool of circular buffers but I'm following the "think first, code later" strategy :) Thanks

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  • Drupal 6 - I am using drupal_execute to insert a CCK node into my site. Everything is working excep

    - by rdurbin
    $form_state['values']['field_prx_mp3_labels'][0][value] = $mp3_labels; $form_state['values']['taxonomy'][0][value] = array('tags'=>array('1'=>'Music')); $errs = drupal_execute('prx_content_node_form', $form_state, (object) $nodeTmp); This is a Drupal 6 site. I am using drupal_execute to create a node programatically. The first line is working for field_prx_mp3_labels. The second (for taxonomy) is not. Here is what my select on the node add for my cck looks like: <select name="taxonomy[2][]" multiple="multiple" class="form-select" id="edit-taxonomy-2" size="9"><option value="">- None -</option><option value="5">Music</option><option value="6">-Rock/Pop</option><option value="7">-Jazz/Blues</option><option value="8">-Classical</option><option value="9">-Music Documentaries</option><option value="10">-Festivals/Concerts</option><option value="11">Arts</option><option value="19">-Literature</option><option value="12">Nature</option><option value="13">History</option><option value="15">-Music</option><option value="14">Culture</option><option value="17">-American Indian</option><option value="18">-Latino</option><option value="16">-Youth Perspective</option></select> I have tried many many variations for line 2 (relating to the taxonomy). This comment seemed close but it hasn't worked for me: http://drupal.org/node/178506#comment-1155576 Thanks!

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  • No grammar constraints (DTD or XML schema) detected for the document.

    - by fastcodejava
    I have this dtd : http://fast-code.sourceforge.net/template.dtd But when I include in an xml I get the warning : No grammar constraints (DTD or XML schema) detected for the document. The xml is : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE templates PUBLIC "//UNKNOWN/" "http://fast-code.sourceforge.net/template.dtd"> <templates> <template type="type"> <description>Some</description> <variation></variation> <variation-field></variation-field> <allow-multiple-variation></allow-multiple-variation> <class-pattern></class-pattern> <getter-setter>setter</getter-setter> <allowed-file-extensions>java</allowed-file-extensions> <number-required-classes>1</number-required-classes> <template-body> <![CDATA[ Some Data ]]> </template-body> </template> </templates> Any clue?

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  • "Too many indexes on table" error when creating relationships in Microsoft Access 2010.

    - by avianattackarmada
    I have tblUsers which has a primary key of UserID. UserID is used as a foreign key in many tables. Within a table, it is used as a foreign key for multiple fields (e.g. ObserverID, RecorderID, CheckerID). I have successfully added relationships (with in the the MS Access 'Relationship' view), where I have table aliases to do the multiple relationships per table: *tblUser.UserID - 1 to many - tblResight.ObserverID *tblUser_1.UserID - 1 to many - tblResight.CheckerID After creating about 25 relationships with enforcement of referential integrity, when I try to add an additional one, I get the following error: "The operation failed. There are too many indexes on table 'tblUsers.' Delete some of the indexes on the table and try the operation again." I ran the code I found here and it returned that I have 6 indexes on tblUsers. I know there is a limit of 32 indexes per table. Am I using the relationship GUI wrong? Does access create an index for the enforcement of referential integrity any time I create a relationship (especially indexes that wouldn't turn up when I ran the script)? I'm kind of baffled, any help would be appreciated.

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  • NSFetchedResultsController on secondary UITableView - how to query data?

    - by Jason
    I am creating a core-data based Navigation iPhone app with multiple screens. Let's say it is a flash-card application. The data model is very simple, with only two entities: Language, and CardSet. There is a one-to-many relationship between the Language entity and the CardSet entities, so each Language may contain multiple CardSets. In other words, Language has a one-to-many relationship Language.cardSets which points to the list of CardSets, and CardSet has a relationship CardSet.language which points to the Language. There are two screens: (1) An initial TableView screen, which displays the list of languages; and (2) a secondary TableView screen, which displays the list of CardSets in the Language. In the initial screen, which lists the languages, I am using NSFetchedResultsController to keep the list of languages up-to-date. The screen passes the Language selected to the secondary screen. On the secondary screen, I am trying to figure out whether I should again use an NSFetchedResultsController to maintain the list of CardSets, or if I should work through Language.cardSets to simply pull the list out of the object model. The latter makes the most sense programatically because I already have the Language - but then it would not automatically be updated on changes. I have looked at the NSFetchedResultsController documentation, and it seems like I can easily create predicates based on attributes - but not relationships. I.e., I can create the following NSFetchedResultsController: NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name LIKE[c] 'Chuck Norris'"]; How can I access my data through the direct relationship - Language.cardSets - and also have the table auto-update using NSFetchedResultsController? Is this possible?

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  • Get the first and last posts in a thread

    - by Grampa
    I am trying to code a forum website and I want to display a list of threads. Each thread should be accompanied by info about the first post (the "head" of the thread) as well as the last. My current database structure is the following: threads table: id - int, PK, not NULL, auto-increment name - varchar(255) posts table: id - int, PK, not NULL, auto-increment thread_id - FK for threads The tables have other fields as well, but they are not relevant for the query. I am interested in querying threads and somehow JOINing with posts so that I obtain both the first and last post for each thread in a single query (with no subqueries). So far I am able to do it using multiple queries, and I have defined the first post as being: SELECT * FROM threads t LEFT JOIN posts p ON t.id = p.thread_id ORDER BY p.id LIMIT 0, 1 The last post is pretty much the same except for ORDER BY id DESC. Now, I could select multiple threads with their first or last posts, by doing: SELECT * FROM threads t LEFT JOIN posts p ON t.id = p.thread_id ORDER BY p.id GROUP BY t.id But of course I can't get both at once, since I would need to sort both ASC and DESC at the same time. What is the solution here? Is it even possible to use a single query? Is there any way I could change the structure of my tables to facilitate this? If this is not doable, then what tips could you give me to improve the query performance in this particular situation?

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  • Using resources with the same name in Xcode

    - by Roberto
    Is there a way to add multiple resources with the same name to an Xcode project and have 1 of them take priority over the others? Example: I added 2 files, both called icon.png, to an Xcode project. They are on different folders in the file system (Folder1/icon.png and Folder2/icon.png) and on different groups in Xcode. Is there a way to tell Xcode to have Folder2/icon.png take priority over Folder1/icon.png? And if only 1 icon.png exists, then use that one. Thanks. EDIT (2010-12-23): You can have multiple files with the same name in an Xcode project even if they are not in separate folder references, but they are in separate groups. Once compiled, the app bundle (which will be flat with no folders in it), will only have one copy of the file (icon.png). How do you pick which copy of the file to use? I was told that you can do this for BlackBerry. It works something like this: The compiler will go down the list of files in the project and start adding them to the app bundle. If it sees a duplicate, it will overwrite it (or not), so the files at the bottom (or at the top) will have higher precedence and will be the final bundle.

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