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• How can I automatically generate sql update scripts when some data is updated ?

  - by Brann

  I'd like to automatically generate an update script each time a value is modified in my database. In other words, if a stored procedure, or a query, or whatever updates column a with value b in table c (which as a pk column (i,j...k), I want to generate this : update c set a=b where i=... and j=... and k=... and store it somewhere (for example as a raw string in a table). To complicate things, I want the script to be generated only if the update has been made by a specific user. Good news is that I've got a primary key defined for all my tables. I can see how to do this using a trigger, but I would need to generate specific triggers for each table, and to update them each and every-time my schema changes. I guess there are some built-in ways to do this as SQL server sometimes need to store this kind of things (while using transactional replication for example), but couldn't find anything so far ... any ideas ? I'm also interested in ways to automatically generate triggers (probably using triggers - meta triggers, huh? - since I will need to update triggers automatically when the schema change)

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• How do I improve this design for dealing with intersecting date ranges and resolving date range conf

  - by derdo

  I am working on some code that deals with date ranges. I have pricing activities that have a starting-date and an end-date to set a certain price for that range. There are multiple pricing activities with intersecting date ranges. What I ultimately need is the ability to query valid prices for a date range. I pass in (jan1,jan31) and I get back a list that says jan1--jan10 $4 , jan11--jan19 $3 jan20--jan31 $4. There are priorities between pricing activities. Some type of pricing activities have high priority, so they override other pricing activities and for certain type of pricing activities lowest price wins etc. I currently have a class that holds these pricing activities and keeps a resolved pricing calendar. As I add new pricing activities I update the resolved calendar. As I write more tests/code, it started to get very complicated with all the different cases (pricing activities intersecting in different ways). I am ending up with very complicated code where I am resolving a newly added pricing activity. See AddPricingActivity() method below. Can anybody think of a simpler way to deal with this? Could there be similar code somewhere out there? Public class PricingActivity() { DateTime startDate; DateTime endDate; Double price; Public bool StartsBeforeEndsAfter (PricingActivity pAct) { // pAct covers this pricing activity } Public bool StartsMiddleEndsAfter (PricingActivity pAct){ // early part of pAct Itersects with later part of this pricing activity } //more similar methods to cover all the combinations of intersecting } Public Class PricingActivityList() { List<PricingActivity> activities; SortedDictionary<Date, PricingActivity> resolvedPricingCalendar; Public void AddPricingActivity(PricingActivity pAct) { //update the resolvedCalendar //go over each activity and find intersecting ones //update the resolved calendar correctly //depending on the type of the intersection //this part is getting out of hand….. } }

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• Optimzing TSQL code

  - by adopilot

  My job is the maintain one application which heavy use SQL server (MSSQL2005). Until now middle server stores TSQL codes in XML and send dynamic TSQL queries without using stored procs. As I am able change those XML queries I want to migrate most of my queries to stored procs. Question is folowing: Most of my queries have same Where conditions against one table Sample: Select ..... from .... where .... and (a.vrsta_id = @vrsta_id or @vrsta_id = 0) and (a.podvrsta_id = @podvrsta_id or @podvrsta_id = 0) and (a.podgrupa_2 = @podgrupa2_id or @podgrupa2_id = 0) and ( (a.id in (select art_id from osobina_veze where podosobina_id in (select ado from dbo.fn_ado_param_int(@podosobina)) group by art_id having count(art_id)= @podosobina_count )) or ('0' = @podosobina) ) They also have same where conditions on other table. How I should organize my code ? What is proper way ? Should I make table valued function that I will use in all queries or use #Temp tables and simple inner join my query to that each time when proc executing? or use #temp filed by table valued function ? or leave all queries with this large where clause and hope that index is going to do their jobs. or use WITH(statement)

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• Cast object to interface when created via reflection

  - by Al

  I'm trying some stuff out in Android and I'm stuck at when trying to cast a class in another .apk to my interface. I have the interface and various classes in other .apks that implement that interface. I find the other classes using PackageManager's query methods and use Application#createPackageContext() to get the classloader for that context. I then load the class, create a new instance and try to cast it to my interface, which I know it definitely implements. When I try to cast, it throws a class cast exception. I tried various things like loading the interface first, using Class#asSubclass, etc, none of which work. Class#getInterfaces() shows the interface is implemented. My code is below: PackageManager pm = getPackageManager(); List<ResolveInfo> lr = pm.queryIntentServices(new Intent("com.example.some.action"), 0); ArrayList<MyInterface> list = new ArrayList<MyInterface>(); for (ResolveInfo r : lr) { try { Context c = getApplication().createPackageContext(r.serviceInfo.packageName, Context.CONTEXT_IGNORE_SECURITY | Context.CONTEXT_INCLUDE_CODE); ClassLoader cl = c.getClassLoader(); String className = r.serviceInfo.name; if (className != null) { try { Class<?> cls = cl.loadClass(className); Object o = cls.newInstance(); if (o instanceof MyInterface) { //fails list.add((MyInterface) o); } } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } // some exceptions removed for readability } } catch (NameNotFoundException e1) { e1.printStackTrace(); }

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• Theory: "Lexical Encoding"

  - by _ande_turner_

  I am using the term "Lexical Encoding" for my lack of a better one. A Word is arguably the fundamental unit of communication as opposed to a Letter. Unicode tries to assign a numeric value to each Letter of all known Alphabets. What is a Letter to one language, is a Glyph to another. Unicode 5.1 assigns more than 100,000 values to these Glyphs currently. Out of the approximately 180,000 Words being used in Modern English, it is said that with a vocabulary of about 2,000 Words, you should be able to converse in general terms. A "Lexical Encoding" would encode each Word not each Letter, and encapsulate them within a Sentence. // An simplified example of a "Lexical Encoding" String sentence = "How are you today?"; int[] sentence = { 93, 22, 14, 330, QUERY }; In this example each Token in the String was encoded as an Integer. The Encoding Scheme here simply assigned an int value based on generalised statistical ranking of word usage, and assigned a constant to the question mark. Ultimately, a Word has both a Spelling & Meaning though. Any "Lexical Encoding" would preserve the meaning and intent of the Sentence as a whole, and not be language specific. An English sentence would be encoded into "...language-neutral atomic elements of meaning ..." which could then be reconstituted into any language with a structured Syntactic Form and Grammatical Structure. What are other examples of "Lexical Encoding" techniques? If you were interested in where the word-usage statistics come from : http://www.wordcount.org

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• @PrePersist with entity inheritance

  - by gerry

  I'm having some problems with inheritance and the @PrePersist annotation. My source code looks like the following: _the 'base' class with the annotated updateDates() method: @javax.persistence.Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class Base implements Serializable{ ... @Id @GeneratedValue protected Long id; ... @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date creationDate; @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date lastModificationDate; ... public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public Date getLastModificationDate() { return lastModificationDate; } public void setLastModificationDate(Date lastModificationDate) { this.lastModificationDate = lastModificationDate; } ... @PrePersist protected void updateDates() { if (creationDate == null) { creationDate = new Date(); } lastModificationDate = new Date(); } } _ now the 'Child' class that should inherit all methods "and annotations" from the base class: @javax.persistence.Entity @NamedQueries({ @NamedQuery(name=Sensor.QUERY_FIND_ALL, query="SELECT s FROM Sensor s") }) public class Sensor extends Entity { ... // additional attributes @Column(nullable=false) protected String value; ... // additional getters, setters ... } If I store/persist instances of the Base class to the database, everything works fine. The dates are getting updated. But now, if I want to persist a child instance, the database throws the following exception: MySQLIntegrityConstraintViolationException: Column 'CREATIONDATE' cannot be null So, in my opinion, this is caused because in Child the method "@PrePersist protected void updateDates()" is not called/invoked before persisting the instances to the database. What is wrong with my code?

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• Linq to sql Repository pattern , Some doubts

  - by MindlessProgrammer

  I am using repository pattern with linq to sql, I am using a repository class per table. I want to know , am i doing at good/standard way, ContactRepository Contact GetByID() Contact GetAll() COntactTagRepository List<ContactTag> Get(long contactID) List<ContactTag> GetAll() List<ContactTagDetail> GetAllDetails() class ContactTagDetail { public Contact Contact {get;set;} public ContactTag COntactTag {get;set;} } When i need a contact i call method in contactrepository, same for contacttag but when i need contact and tags together i call GetDetais() in ContactTag repository its not returning the COntactTag entity generated by the orm insted its returning ContactTagDetail entity conatining both COntact and COntactTag generated by the orm, i know i can simple call GetAll in COntactTag repository and can access Contact.ContactTag but as its linq to sql it will there is no option to Deferred Load in query level, so whenever i need a entity with a related entity i create a projection class Another doubt is where i really need to right the method i can do it in both contact & ContactTag repostitory like In contact repository GetALlWithTags() or something but i am doing it in in COntactTag repository Whats your suggestions ?

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• iPhone Adding Controls (UIButton, UILabel etc.) on a Playing Video!

  - by Taimur Hamza

  I have been assigned an 'easy' task of adding a button over a playing video. I m terming it easy as i have got the sample code downloaded from Apple's sample code. http://rapidshare.com/files/393248642/MoviePlayer_iPhone.zip Anybody who wants to reply to my query and intends to help should download this project and run it otherwise it wudnt be easy to understand my problem. Thanks! And now the weird problem i am facing is: In the sample project developer has added the view ( UILabel and UIButton ) in the Appdelegate. And i want it other xib files not the App delegate . Fine i added a view 'myButtonABC' instead of 'My Overlay View'. And added this code in my xib file's implementation file. (void)viewDidLoad { TaimurAppDelegate *appDelegate = (TaimurAppDelegate *)[[UIApplication sharedApplication] delegate]; [appDelegate initAndPlayMovie:[self localMovieURL]]; NSArray *windows = [[UIApplication sharedApplication] windows]; if ([windows count] 1) { UIWindow *moviePlayerWindow = [[UIApplication sharedApplication] keyWindow]; [moviePlayerWindow addSubview:self.myABC]; } } Now my question is do i need to declare a UIWindow object in the header file here. As i am not working in the app delegate class. As i said previously i have to add this button over a video in other screen and not on the main screen. The third question is can anyone, which in fact is the most imp of all. In my view , if i am able to do this one my problem would be solved. As i have spend considerable amount of time on this task so far. The question is " How can i connect myABCButton (which is a view added to my xib file ) to the File's Owner. Thanks for your patience. Replies Appreciated ! Taimur

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• Custom Detail in Linq-to-SQL Master-Detail DataGridViews

  - by Andres

  Hi, looking for a way to create Linq-to-SQL Master-Detail WinForms DataGridViews where the Detail part of the Linq query is a custom one. Can do fine this: DataClasses1DataContext db = new DataClasses1DataContext(".\\SQLExpress"); var myQuery = from o in db.Orders select o; dataGridView1.DataSource = new BindingSource() { DataSource = myQuery }; dataGridView2.DataSource = new BindingSource() { DataSource = dataGridView1.DataSource, DataMember = "OrderDetails" }; but I'd like to have the Detail part under my precise control, like var myQuery = from o in db.Orders join od in db.OrderDetails on o.ID equals od.OrderID into MyOwnSubQuery select o; and use it for the second grid: dataGridView2.DataSource = new BindingSource() { DataSource = dataGridView1.DataSource, DataMember = "MyOwnSubQuery" // not working... }; the real reason I want it is a bit more complex (I'd like to have the Detail part to be some not-pre-defined join actually), but I'm hoping the above conveyed the idea. Can I only have the Detail part as a plain sub-table coming out of the pre-defined relation or can I do more complex stuff with the Detail part? Does anyone else feel this is kind of limited (if the first example is the best we can do)? Thanks!

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• how can I save/keep-in-sync an in-memory graph of objects with the database?

  - by Greg

  Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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• Understanding many to many relationships and Entity Framework

  - by Anders Svensson

  I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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• How to hold payment in paygate for a while?

  - by Fero

  HI all, I have a query regarding holding the payment in PAYGATE PAYMENT GATEWAY. Here is the problem in brief. I am doing a website where the payment should be made only a certain members buy the product. For Example if there is an iPhone in my site, then that particular phone must be buy by certain quantities which given by admin. It may be done one by one user or a single user can buy all the quantities at a single time. In this case as a developer how can i able to hold the payment which received by user? Because i don't want to receive the payments until the certain quantities bought. Because if certain quantities were not buy i need to refund the money to their account. We don't like to do this process. That's why we are looking for holding the payment. Is it possible or what is the best way to solve this problem? Please let me know what is you professional opinion? thanks in advance... Please let me know what is you professional opinion?

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• Optimize website for touch devices

  - by gregers

  On a touch device like iPhone/iPad/Android it can be difficult to hit a small button with your finger. There is no cross-browser way to detect touch devices with CSS media queries that I know of. So I check if the browser has support for javascript touch events. Until now, other browsers haven't supported them, but the latest Google Chrome on dev channel enabled touch events (even for non touch devices). And I suspect other browser makers will follow, since laptops with touch screens are comming. This is the test I use: function isTouchDevice() { try { document.createEvent("TouchEvent"); return true; } catch (e) { return false; } } The problem is that this only tests if the browser has support for touch events, not the device. Does anyone know of The Correct[tm] way of giving touch devices better user experience? Other than sniffing user agent. Mozilla has a media query for touch devices. But I haven't seen anything like it in any other browser: https://developer.mozilla.org/En/CSS/Media_queries#-moz-touch-enabled Update: I want to avoid using a separate page/site for mobile/touch devices. The solution has to detect touch devices with object detection or similar from JavaScript, or include a custom touch-CSS without user agent sniffing! The main reason I asked, was to make sure it's not possible today, before I contact the css3 working group.

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• Easily (as in WYSIWYG) customize the docbook output

  - by Sukima

  I've used DocBook in the past and I love the idea behind the separation of content from presentation. I am very comfortable editing XML directly. In my extensive search to find the best documenting solution for my needs I am always coming back to this one solution: DocBook - Build system (ant, make, etc.) - Output I have seen lots of information concerning the best WYSIWYG, XML, Text editors for writing DocBook including alternative markup languages like asciidoc. All these solutions focus on the creation of DocBook or the nightmare of the DocBook tool chain. No one ever addresses the Output side other then to say "Just use XSL" or "Custom scripts" When tasked to make a document or manual I don't want to worry about spending countless hours attempting to reprogram, customize, and modify the XSL, CSS, and shell scripts (i.e. O'Riely books). That is a very arduous task. My query: is there a tool that makes the customizing easier? And is there anything that could be similar to say Pages or Word in that the user creates a template and the tool chain does the rest? Attempting to do a visual task like pretty logos and fixing all the broken layouts that the default XSL comes up with (pagination is a mess) is very difficult from a text editor. Content is easy. Editing DocBook XSL was truly a nightmare when I did it in the past. I've searched and I find lots of info on XML editors but nothing on XSL editors. Or am I lacking a key understanding of the process. Thanks.

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• How to avoid overlapping date ranges when using a grouping clause?

  - by k rey

  I have a situation where I need to find time spans between value changes. I tried a simple group by clause but it eliminates overlapping changes. Consider the following example: create table #items ( code varchar(4) , class varchar(4) , txdate datetime ) insert into #items (code, class, txdate) values ('A', 'C', '2010-01-01'); insert into #items (code, class, txdate) values ('A', 'C', '2010-01-02'); insert into #items (code, class, txdate) values ('A', 'C', '2010-01-03'); insert into #items (code, class, txdate) values ('A', 'D', '2010-01-04'); insert into #items (code, class, txdate) values ('A', 'D', '2010-01-05'); insert into #items (code, class, txdate) values ('A', 'C', '2010-01-06'); insert into #items (code, class, txdate) values ('A', 'C', '2010-01-07'); insert into #items (code, class, txdate) values ('A', 'D', '2010-01-08'); insert into #items (code, class, txdate) values ('A', 'D', '2010-01-09'); select code , class , min(txdate) mindate , max(txdate) maxdate from #items group by code, class This returns the following results (notice the overlapping date ranges): |code|class|mindate |maxdate | ---------------------------------- |A |C |2010-01-01|2010-01-07| |A |D |2010-01-04|2010-01-09| I would like to have the query return the following: |code|class|mindate |maxdate | ---------------------------------- |A |C |2010-01-01|2010-01-03| |A |D |2010-01-04|2010-01-05| |A |C |2010-01-06|2010-01-07| |A |D |2010-01-08|2010-01-09| Any ideas and suggestions?

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• Using conditionals in Linq Programatically

  - by Mike B

  I was just reading a recent question on using conditionals in Linq and it reminded me of an issue I have not been able to resolve. When building Linq to SQL queries programatically how can this be done when the number of conditionals is not known until runtime? For instance in the code below the first clause creates an IQueryable that, if executed, would select all the tasks (called issues) in the database, the 2nd clause will refine that to just issues assigned to one department if one has been selected in a combobox (Which has it's selected item bound to the departmentToShow property). How could I do this using the selectedItems collection instead? IQueryable<Issue> issuesQuery; // Will select all tasks issuesQuery = from i in db.Issues orderby i.IssDueDate, i.IssUrgency select i; // Filters out all other Departments if one is selected if (departmentToShow != "All") { issuesQuery = from i in issuesQuery where i.IssDepartment == departmentToShow select i; } By the way, the above code is simplified, in the actual code there are about a dozen clauses that refine the query based on the users search and filter settings.

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• SS3: the method 'fortemplate' does not exist on 'ArrayList'

  - by Fraser

  In Silverstripe 3, I'm trying to run some custom SQL and return the result for handling in my template: function getListings(){ $sqlQuery = new SQLQuery(); $sqlQuery->setFrom('ListingCategory_Listings'); $sqlQuery->selectField('*'); $sqlQuery->addLeftJoin('Listing', '"ListingCategory_Listings"."ListingID" = "Listing"."ID"'); $sqlQuery->addLeftJoin('SiteTree_Live', '"Listing"."ID" = "SiteTree_Live"."ID"'); $sqlQuery->addLeftJoin('ListingCategory', '"ListingCategory_Listings"."ListingCategoryID" = "ListingCategory"."ID"'); $sqlQuery->addLeftJoin('File', '"ListingCategory"."IconID" = "File"."ID"'); $result = $sqlQuery->execute(); //return $result; //$dataObject = new DataList(); $dataObject = new ArrayList(); foreach($result as $row) { $dataObject->push(new ArrayData($row)); } return $dataObject; } However, this is giving me the error: Uncaught Exception: Object-__call(): the method 'fortemplate' does not exist on 'ArrayList' What am I doing wrong here and how can I get the result of this query into my template?

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• DataReader already open when using LINQ

  - by Jamie Dixon

  I've got a static class containing a static field which makes reference to a wrapper object of a DataContext. The DataContext is basically generated by Visual Studio when we created a dbml file & contains methods for each of the stored procedures we have in the DB. Our class basically has a bunch of static methods that fire off each of these stored proc methods & then returns an array based on a LINQ query. Example: public static TwoFieldBarData[] GetAgesReportData(string pct) { return DataContext .BreakdownOfUsersByAge(Constants.USER_MEDICAL_PROFILE_KEY, pct) .Select(x => new TwoFieldBarData(x.DisplayName, x.LeftValue, x.RightValue, x.TotalCount)) .ToArray(); } Every now and then, we get the following error: There is already an open DataReader associated with this Command which must be closed firs This is happening intermittently and I'm curious as to what is going on. My guess is that when there's some lag between one method executing and the next one firing, it's locking up the DataContext and throwing the error. Could this be a case for wrapping each of the DataContext LINQ calls in a lock(){} to obtain exclusivity to that type and ensure other requests are queued?

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• Redirecting users after destroy

  - by mathee

  I have 3 models: Questions, Answers, and Profiles (I know, it should be called "Users"). When you view a question Q, I query the database for the answers to Q. (They are linked by id.) In the view, the current user has the option to delete his answer by clicking on the destroy link displayed next to his answer: %table %tr %td Answers: - @answers.each do |a| %tr %td - @provider = Profile.find(a.provider) %i #{h @provider.username} said: %br #{h a.description} %td = link_to 'View full answer', a %td - if a.provider == @profile.id #{link_to 'Delete my answer', a, :confirm => 'Are you sure?', :method => :delete} The problem is that when the user clicks on the destroy link, it redirects to the /answers/index. I want it to redirect to /questions/Q. What's the best way to do this? I know that there's a redirect_to method, but I don't know how to implement it when I want to redirect to an action for a different controller. It also needs to remember the question from which the answer is being deleted. I tried passing something like :question_id in link_to as: #{link_to 'Delete my answer', a, :confirm => 'Are you sure?', :question_id => @question.id, :method => :delete} In AnswersController#destroy: def destroy @answer = Answer.find(params[:id]) @answer.destroy respond_to do |format| format.html { redirect_to(answers_url) } format.xml { head :ok } end @question = Question.find(params[:question_id]) redirect_to question_path(@question) end The :question_id information is not passed to the destroy method, so I get this error: Couldn't find Question without an ID To confirm, I added a puts call before Question.find, and it returned nil.

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• php parsing speed optimization

  - by Arnaud

  I would like to add tooltip or generate link according to the element available in the database, for exemple if the html page printed is: to reboot your linux host in single-user mode you can ... I will use explode(" ", $row[page]) and the idea is now to lookup for every single word in the page to find out if they have a related referance in this exemple let's say i've got a table referance an one entry for reboot and one for linux reboot: restart a computeur linux: operating system now my output will look like (replaced < and by @) to @a href="ref/reboot"@reboot@/a@ your @a href="ref/linux"@linux@/a@ host in single-user mode you can ... Instead of have a static list generated when I saved the content, if I add more keyword in the future, then the text will become more interactive. My main concerne and question is how can I create a efficient enough process to do it ? Should I store all the db entry in an array and compare them ? Do an sql query for each word (seems to be crazy) Dump the table in a file and use a very long regex or a "grep -f pattern data" way of doing it? Or or or or I'm sure it must be a better way of doing it, just don't have a clue about it, or maybe this will be far too resource un-friendly and I should avoid doing such things. Cheers!

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• SQL Inner Join : DB stuck

  - by SurfingCat

  I postet this question a few days ago but I didn't explain exactly what I want. I ask the question better formulated again: To clarify my problem I added some new information: I got an MySQL DB with MyISAM tables. The two relevant tables are: * orders_products: orders_products_id, orders_id, product_id, product_name, product_price, product_name, product_model, final_price, ... * products: products_id, manufacturers_id, ... (for full information about the tables see screenshot products (Screenshot) and screenshot orders_products (Screenshot)) Now what I want is this: - Get all Orders who ordered products with manufacturers_id = 1. And the product name of the product of this order (with manufacturers_id = 1). Grouped by orders. What I did so far is this: SELECT op.orders_id, p.products_id, op.products_name, op.products_price, op.products_quantity FROM orders_products op , products p INNER JOIN products ON op.products_id = p.products_id WHERE p.manufacturers_id = 1 AND p.orders_id > 10000 p.orders_id 10000 for testing to get only a few order_id's. But thies query takes much time to get executed if it even works. Two times the sql server stucked. Where is the mistake?

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• [PHP] Kohana-v3 ORM parent relationship

  - by VDVLeon

  Hi all, I just started with the version 3 of the Kohana Framework. I have worked a little with the $_has_many etc. Now I have the table pages. The primary key is pageID. The table has a column called parentPageID. Now I want to make a ORM model who, when accesed like this $page->parent->find() returns the page identified by parentPageID. I have the following already: // Settings protected $_table_name = 'pages'; protected $_primary_key = 'pageID'; protected $_has_one = array( 'parent' => array( 'model' => 'page', 'foreign_key' => 'parentPageID', ), ); But that does not work, it simply returns the first page from the table. Last query says this: SELECT `pages`.* FROM `pages` ORDER BY `pages`.`pageID` ASC LIMIT 1 Does somebody know how to solve this? I know this can: $parent = $page->parent->find($page->parentPageID); but it must be and can be cleaner (I think).

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• Are Dynamic Prepared Statements Bad? (with php + mysqli)

  - by John

  I like the flexibility of Dynamic SQL and I like the security + improved performance of Prepared Statements. So what I really want is Dynamic Prepared Statements, which is troublesome to make because bind_param and bind_result accept "fixed" number of arguments. So I made use of an eval() statement to get around this problem. But I get the feeling this is a bad idea. Here's example code of what I mean // array of WHERE conditions $param = array('customer_id'=>1, 'qty'=>'2'); $stmt = $mysqli->stmt_init(); $types = ''; $bindParam = array(); $where = ''; $count = 0; // build the dynamic sql and param bind conditions foreach($param as $key=>$val) { $types .= 'i'; $bindParam[] = '$p'.$count.'=$param["'.$key.'"]'; $where .= "$key = ? AND "; $count++; } // prepare the query -- SELECT * FROM t1 WHERE customer_id = ? AND qty = ? $sql = "SELECT * FROM t1 WHERE ".substr($where, 0, strlen($where)-4); $stmt->prepare($sql); // assemble the bind_param command $command = '$stmt->bind_param($types, '.implode(', ', $bindParam).');'; // evaluate the command -- $stmt->bind_param($types,$p0=$param["customer_id"],$p1=$param["qty"]); eval($command); Is that last eval() statement a bad idea? I tried to avoid code injection by encapsulating values behind the variable name $param. Does anyone have an opinion or other suggestions? Are there issues I need to be aware of?

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• Modeling complex hierarchies

  - by jdn

  To gain some experience, I am trying to make an expert system that can answer queries about the animal kingdom. However, I have run into a problem modeling the domain. I originally considered the animal kingdom hierarchy to be drawn like -animal -bird -carnivore -hawk -herbivore -bluejay -mammals -carnivores -herbivores This I figured would allow me to make queries easily like "give me all birds", but would be much more expensive to say "give me all carnivores", so I rewrote the hierarchy to look like: -animal -carnivore -birds -hawk -mammals -xyz -herbivores -birds -bluejay -mammals But now it will be much slower to query "give me all birds." This is of course a simple example, but it got me thinking that I don't really know how to model complex relationships that are not so strictly hierarchical in nature in the context of writing an expert system to answer queries as stated above. A directed, cyclic graph seems like it could mathematically solve the problem, but storing this in a relational database and maintaining it (updates) would seem like a nightmare to me. I would like to know how people typically model such things. Explanations or pointers to resources to read further would be acceptable and appreciated.

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• Are document-oriented databases any more suitable than relational ones for persisting objects?

  - by Owen Fraser-Green

  In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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