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• Getting a sorted distinct list from mySQL

  - by Stomped

  Goal I'l like to get a list of unique FID's ordered by the the one which has most recently been changed. In this sample table it should return FIDs in the order of 150, 194, 122 Example Data ID FID changeDate ---------------------------------------------- 1 194 2010-04-01 2 122 2010-04-02 3 194 2010-04-03 4 150 2010-04-04 My Attempt I thought distinct and order by would do the trick. I initially tried: SELECT distinct `FID` FROM `tblHistory` WHERE 1 ORDER BY changeDate desc # Returns 150, 122, 194 using GROUP BY has the same result. I'm just barely a SQL amateur, and I'm a bit hung up. What seems to be happening is the aggregating functions find the first occurrence of each and then perform the sort. Is there a way I can get the result I want straight from mySQL or do I have to grab all the data and then sort it in the PHP?

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• Windows Mobile : How to bind dropdown's selectedvalue to a column in table A and the list data to a

  - by Rob

  Hi, I am trying to learn the basics of Windows Mobile development against SQL CE and have come across a basic problem. I have two tables. One called Customers that stores customer info and has an identity column called ID as the primary key. The other table is called Orders which has a column called CustomerID (the FK constraint is present). I have added a DataSet to the project that contains both tables and have autogenerated the edit/view forms. This has produced a text control for the CustomerID column in the Order table for the new/edit form and I deleted it and replaced it with a dropdown list. Then, using the 'Advanced' databinding options (in Properties) I set the datasource of the list to the Customers table setting the value to the ID field and the text to the CustomerName field. I then set the SelectedValue of the list box to the CustomerID field of the Orders dataset. So far so good. When I run the app in the emulator and view the 'New' form for Orders the Customer dropdown is indeed populated with a list of customer names and I can select one and happily create a new order successfully. This is confirmed when I see the order appear in the Orders Grid form. However, when I then click on the order in the grid and then select 'Edit' the order loads but the dropdown always shows the first customer in the list and doesn't seem to bind the SelectedValue to the Orders dataset CustomerID field. Now I am an ASP.NET guy and normally hand craft the DAL and it's binding to the UI so I'm not entirely sure where to look to investigate what is going wrong here as this is all generated code. I am sure it is something very trivial but any pointers would be appreciated. My gut feeling is that the SelectedValue and the Customers.CustomerID values do not match for some reason? Many thanks, Rob.

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• Curve fitting: Find a CDF (or any function) that satisfies a list of constraints.

  - by dreeves

  I have some constraints on a CDF in the form of a list of x-values and for each x-value, a pair of y-values that the CDF must lie between. We can represent that as a list of {x,y1,y2} triples such as constraints = {{0, 0, 0}, {1, 0.00311936, 0.00416369}, {2, 0.0847077, 0.109064}, {3, 0.272142, 0.354692}, {4, 0.53198, 0.646113}, {5, 0.623413, 0.743102}, {6, 0.744714, 0.905966}} Graphically that looks like this: And since this is a CDF there's an additional implicit constraint of {Infinity, 1, 1} Ie, the function must never exceed 1. Also, it must be monotone. Now, without making any assumptions about its functional form, we want to find a curve that respects those constraints. For example: (I cheated to get that one: I actually started with a nice log-normal distribution and then generated fake constraints based on it.) One possibility is a straight interpolation through the midpoints of the constraints: mids = ({#1, Mean[{#2,#3}]}&) @@@ constraints f = Interpolation[mids, InterpolationOrder->0] Plotted, f looks like this: That sort of technically satisfies the constraints but it needs smoothing. We can increase the interpolation order but now it violates the implicit constraints (always less than one, and monotone): How can I get a curve that looks as much like the first one above as possible? Note that NonLinearModelFit with a LogNormalDistribution will do the trick in this example but is insufficiently general as sometimes there will sometimes not exist a log-normal distribution satisfying the constraints.

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• Should a given URI in a RESTful architecture always return the same response?

  - by keithjgrant

  This is kind of a follow-up question to this one. So is having a unique response for any given URI a core tenant of RESTful architecture? A lot of discussion here tends that direction, but I haven't seen it anywhere as a "hard and fast" rule. I understand the value of it (for caching, crawling, passing links, etc), but I also see things like the twitter API violate it (A request to http://api.twitter.com/1/statuses/friends_timeline.xml will vary based on the username given), and I understand there are times when it may be necessary--not to mention that a chronologically paged resource will also change as new elements are added. Should I strive for varied responses from the same URI to be eliminated altogether, or do I just accept that sometimes it isn't practical, and as long as I minimize its occurrence, I'll be in decent shape.

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• Should I use concrete Inheritance or not?

  - by Mez

  I have a project using Propel where I have three objects (potentially more in the future) Occasion Event extends Occasion Gig extends Occasion Occasion is an item that has the shared things, that will always be needed (Venue, start, end etc) With this - I want to be able to add in extra functionality, say for example, adding "Band" objects to the Gig object, or "Flyers" to an "Event" object. For this, I plan to create objects for these. However, without concrete inheritance, I have to have the foreign key point to the Occasion object - giving the (propel generated) functions for all of these extra bits to anything inherited from Occasion. I could, in theory do this without a foreign constraint, and add in functions to use the Peer or Query classes to get things related to the "Gig" or similar. Whereas with concrete inheritance, I would only have these functions in the things where they are. I think the decision here is whether I should Duck Type the objects (after all they are occasions) or whether I should just use the "Occasion" object as a "template" (only being used to search for things, like, all occasions at a venue) Thoughts? Comments?

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• Data logged to a file; how do I rotate logs and how do I parse the data to not have 'gaps' in the da

  - by phidah

  I've got a web application that, for performance reasons, throws any data sent into a logfile. I've got two concerns with this approach: How do I best rotate logs, in order to not lose data? For each user session multiple requests are logged. Each request has a unique id so there is an easy way for me to tie the requests to the session. The problem is, however, that if I rotate the logs I risk ending up with one request in one log and another request in another log. How do I arrange my parsing in a way that allows me to parse all requests from a given session? I am willing to define a session timelimit, for example that the requests must, at maximum be 30 minutes apart. If I had a hourly log rotation at 00 minutes: What if the user made one request at 13:59 and one at 14:01 - The user would end up having requests in two different logs.

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• InvalidOperationException When XML Serializing Inherited Class

  - by Nick

  I am having an issue serializing a c# class to an XML file that has a base class... here is a simple example: namespace Domain { [Serializable] public class ClassA { public virtual int MyProperty { get; set; } } } namespace Derived { public class ClassA : Domain.ClassA { public override int MyProperty { get { return 1; } set { /* Do Nothing */ } } } } When I attempt to serialize an instance of Derived.ClassA, I receive the following exception: InvalidOperationException(Types 'Domain.ClassA' and 'Derived.ClassA' both use the XML type name 'ClassA', from the namespace ". Use XML attributes to specify a unique XML name and/or namespace for the type.) The problem is that I want to create a single base class that simply defines the structure of the XML file, and then allow anyone else to derive from that class to insert business rules, but that the formatting will come through from the base. Is this possible, and if so, how do I attribute the base class to allow this?

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• Mapping composite foreign keys in a many-many relationship, with overlapping components.

  - by Kirk Broadhurst

  I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

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• LINQ to SQL - Why can't you use a WHERE after an ORDER BY?

  - by MCS

  The following code: // select all orders var orders = from o in FoodOrders where o.STATUS = 1 order by o.ORDER_DATE descending select o; // if customer id is specified, only select orders from specific customer if (customerID!=null) { orders = orders.Where(o => customerID.Equals(o.CUSTOMER_ID)); } gives me the following error: Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Linq.IOrderedQueryable'. An explicit conversion exists (are you missing a cast?) I fixed the error by doing the sorting at the end: // select all orders var orders = from o in FoodOrders where o.STATUS = 1 select o; // if customer id is specified, only select orders from specific customer if (customerID!=null) { orders = orders.Where(o => customerID.Equals(o.CUSTOMER_ID)); } // I'm forced to do the ordering here orders = orders.OrderBy(o => o.ORDER_DATE).Reverse(); But I'm wondering why is this limitation in place? What's the reason the API was designed in such a way that you can't add a where constraint after using an order by operator?

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• Pageview implementation

  - by The Elite Gentleman

  Hi everyone I want to add a pageview feature on my current web application. This page view is based on the count of user viewing the page. It must be unique, i.e. I must not view a person's page 10000 times and record it as 10000 views, just record 1 view instead. My question is, should I base my pageview count on IP address? If not, what is/are the best approach in doing this? I know that if the person has logged in to my system, I can simply use the user id stored in the session and check on the record if the user has/hasn't viewed the page and update accordingly. But for "anonymous" viewers, what is the best approach? Thanks. PS How does Youtube does it?

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• LINQ Join 2 List<T>s

  - by David Murdoch

  Preface: I don't understand what this does: o => o.ID, i => i.ID, (o, id) => o So go easy on me. :-) I have 2 lists that I need to join together: // contains ALL contacts for a customer. // Each item has a unique ID. // There are no duplicates. ContactCollection list1 = myCustomer.GetContacts(); // contains the customer contacts (in list1) relevant to a REPORT // the items in this list may have properties that differ from those in list1. /*****/// e.g.: /*****/ bool SelectedForNotification; /*****/// may be different. ContactCollection list2 = myReport.GetContacts(); I need to create a third ContactCollection that contains all of the contacts in list1 but with the properties of the items in list2, if they are there (list3.Count == list1.Count). I feel as though I'm not making any sense. So, please ask questions in the comments and I'll try to clarify.

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• Single HTML Table from multiple MySQL tables

  - by David Chouinard

  Hi! I've been struggling for a while with this one; I'll try to explain it here as simply as possible. Consider this MySQL table: +----------+-----------+---------+--------+ |status_id |session_id |pilot_id |present | +----------+-----------+---------+--------+ |1 |61 |901 |1 | |2 |63 |901 |1 | |3 |62 |901 |0 | |4 |62 |902 |1 | |5 |63 |903 |1 | +----------+-----------+---------+--------+ Both session_id and pilot_id are foreign keys making reference to a primary key in another table. The same pilot_id can be associated with different session_id, but every pilot_id-session_id combination is unique. I need to make an HTML table (in PHP) that would display the data like this: +----------+---------+---------+---------+ | |61 |62 |63 | +----------+---------+---------+---------+ |901 |X | |X | |902 | |X | | |903 | | |X | +----------+---------+---------+---------+ Hence, rows are pilot_id and columns are session_id. When a pilot_id-session_id combination has a present value of 1, the corresponding cell should be checked. (ie. when the row-combination is zero or the combination does not exist in the MySQL table, nothing should appear in the HTML table) Phew. Any ideas? Thanks!

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• C++: A variation of priority queue

  - by Helltone

  I need some kind of priority queue to store pairs <key, value>. Values are unique, but keys aren't. I will be performing the following operations (most common first): random insertion; retrieving (and removing) all elements with the least key. random removal (by value); I can't use std::priority_queue because it only supports removing the head. For now, I'm using an unsorted std::list. Insertion is performed by just pushing new elements to the back (O(1)). Operation 2 sorts the list with std::sort (O(N*logN)), before performing the actual retrieval. Removal, however, is O(n), which is a bit expensive. Any idea of a better data structure?

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• ASP.NET 4.5 Bundling in Debug Mode - Stale Resources

  - by RPM1984

  Is there any way we can make the ASP.NET 4.5 Bundling functionality generate GUID's as part of the querystring when running in debug mode (e.g bundling turned OFF). The problem is when developing locally, the scripts/CSS files are generated like this: <script type="text/javascript" src="/Content/Scripts/myscript.js" /> So if i change that file, i need to do a hard-refresh (sometimes a few times) to get the file to be picked up by the browser - annoying. Is there any way we can make it render out like this: <script type="text/javascript" src="/Content/Scripts/myscript.js?v=x" /> Where x is a GUID (e.g always unique). Ideas? I'm on ASP.NET MVC 4.

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• "a valid provisioning file for this executable was not found" in XCode

  - by dbonneville

  I'm trying to submit my second app to the App Store. I've followed all the instructions to the best of my knowledge, but I keep getting this error when I try to build and run: "a valid provisioning file for this executable was not found" I'm letting XCode auto select the profile automatically. The one I'd like to select is greyed out. But the dropdown selection in the Build tab of the Target window says "profile doesn't match application identifier" The other thing I don't get about this is that the selection dropdown shows "com.mycompany.myapp" and then "ABCDEDFG.com.mycompany.myapp" (both of those made up) so that I see they don't match. I have the unique identifier profile installed in the Organizer and in plist file. I'm totally confused. I have followed the instructions in my book a few times and just can't get it.

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• Drupal: Two-way communication between unregistered customer and admin

  - by Bryan Folds

  I need to setup a system where customers can choose to Request a Quote for a specific holiday package, where they will enter their personal details as well as their holiday requirements (number of rooms, etc.) and will then allow them to view a page which will have a threaded conversation between them and the admin (so the admin can reply to their quote request on the website). The problem is that most customers won't be registered when they want to request a quote, so I was thinking that the Request a Quote page could silently register the customer as a user (using their personal details) on the same page where it asks for their holiday requirements. The other option I can think of would be to not register them and just email them a unique URL where they can view their quote request and reply to the admin. Could you point me in the right direction on how to do either of those?

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• getting mysql_insert_id() while using ON DUPLICATE KEY UPDATE with PHP

  - by julio

  Hi-- I've found a few answers for this using mySQL alone, but I was hoping someone could show me a way to get the ID of the last inserted or updated row of a mysql DB when using PHP to handle the inserts/updates. Currently I have something like this, where column3 is a unique key, and there's also an id column that's an autoincremented primary key: $query ="INSERT INTO TABLE (column1, column2, column3) VALUES (value1, value2, value3) ON DUPLICATE KEY UPDATE SET column1=value1, column2=value2, column3=value3"; mysql_query($query); $my_id = mysql_insert_id(); $my_id is correct on INSERT, but incorrect when it's updating a row (ON DUPLICATE KEY UPDATE). I have seen several posts with people advising that you use something like INSERT INTO table (a) VALUES (0) ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id) to get a valid ID value when the ON DUPLICATE KEY is invoked-- but will this return that valid ID to the PHP "mysql_insert_id()" function? Thanks for any advice.

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• ASP.NET MVC pass information from controller to view WITHOUT ViewData, ViewModel, or Session

  - by josh

  I have a unique scenario where I want a base controller to grab some data and store it in a list. The list should be accessible from my views just as ViewData is. I will be using this list on every page and would like a cleaner solution than just shoving it in the ViewDataDictionary. After attempting to come up with a solution, I thought I would create a custom ViewPage with a property to hold my list. My custom ViewPage would inherit from System.Web.MVC.ViewPage. However, I do not know where MVC passes the viewdata from the controller off to the view. More importantly, how do I get it to pass my list down to the view? Thanks for the help.

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• mongoid with rails - Database should be a Mongo::DB, not NilClass"

  - by Adam T

  Greetings I am trying to get Mongoid to work with my Rails app and I am getting an error: "Mongoid::Errors::InvalidDatabase in 'Shipment bol should be unique' Database should be a Mongo::DB, not NilClass" I have created the mongoid.yml file in my config directory and have mongodb running as a daemon. The config file is like so: defaults: &defaults host: localhost development: <<: *defaults database: ship-it-development test: <<: *defaults database: ship-it-test production: <<: *defaults host: <%= ENV['MONGOID_HOST'] % port: <%= ENV['MONGOID_PORT'] % database: <%= ENV['MONGOID_DATABASE'] % All of my specs fail with the above error. I am using rails 2.3.8. Anyone have ideas?

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• Any way to make this working dual core in C#?

  - by Frantisek

  Hi, I got a piece of code that loops through the array and looks for the similar and same strings in it - marking it whether it's unique or not. loop X array for I ( loop X array for Y ( If X is prefix of Y do. else if x is same length as Y and it's prefix do something. ) Here is the code to finilize everything for I and corresponding (found/not found) matches in Y. ) I'd like to make this for dual-core to multithread it. To my knowledge it is not possible, but it's highly probable that you may have some idea.

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• rails: date type and GetDate

  - by cbrulak

  This is a follow up to this question: http://stackoverflow.com/questions/2930256/unique-responses-rails-gem I'm going to create an index based on the user id, url and a date type. I want date type (not datetime type) because I want the day, the 24 hour day to be part of the index to avoid duplication of page views counts on the same day. In other words: A view only counts once in a day by a visitor. I also want the default value of that column (viewdate) to be the function GETDATE(). This is what I have in my migration: execute "ALTER TABLEpage_viewsADD COLUMN viewdate datetime DEFAULTGETDATE()`" But the value viewdate is always empty. What am I missing? (as an aside, any other suggestions for accomplishing this goal?)

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• How to get the git commit count?

  - by Splo

  I'd like to get the number of commits of my git repository, a bit like SVN revision numbers. The goal is to use it as a unique, incrementing build number. I currently do like that, on Unix/Cygwin/msysGit: git log --pretty=format:'' | wc -l But I feel it's a bit of a hack. Is there a better way to do that? It would be cool if I actually didn't need wc or even git, so it could work on a bare Windows. Just read a file or a directory structure ...

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• Storing uploaded content on a website

  - by Matt

  For the past 5 years, my typical solution for storing uploaded files (images, videos, documents, etc) was to throw everything into an "upload" folder and give it a unique name. I'm looking to refine my methods for storing uploaded content and I'm just wondering what other methods are used / preferred. I've considered storing each item in their own folder (folder name is the Id in the db) so I can preserve the uploaded file name. I've also considered uploading all media to a locked folder, then using a file handler, which you pass the Id of the file you want to download in the querystring, it would then read the file and send the bytes to the user. This is handy for checking access, and restricting bandwidth for users.

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• What is an index in MySQL?

  - by Eric

  http://i.imgur.com/JdsUK.jpg I created a table like the picture above. What are the "Indexes"? primary key? unique? It works well without setting indexes.. What do they do? why do I need them? Also, I set all String fields to TEXT because I didn't know how many characters I need. Is this a good idea? I don't see any difference. Thanks!

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• How to have a where clause on an insert or an update in Linq to Sql?

  - by Kelsey

  I am trying to convert the following stored proc to a LinqToSql call (this is a simplied version of the SQL): INSERT INTO [MyTable] ([Name], [Value]) SELECT @name, @value WHERE NOT EXISTS(SELECT [Value] FROM [MyTable] WHERE [Value] = @value) The DB does not have a constraint on the field that is getting checked for so in this specific case the check needs to be made manually. Also there are many items constantly being inserted as well so I need to make sure that when this specific insert happens there is no dupe of the value field. My first hunch is to do the following: using (TransactionScope scope = new TransactionScope()) { if (Context.MyTables.SingleOrDefault(t => t.Value == in.Value) != null) { MyLinqModels.MyTable t = new MyLinqModels.MyTable() { Name = in.Name, Value = in.Value }; // Do some stuff in the transaction scope.Complete(); } } This is the first time I have really run into this scenario so I want to make sure I am going about it the right way. Does this seem correct or can anyone suggest a better way of going about it without having two seperate calls? Edit: I am running into a similar issue with an update: UPDATE [AnotherTable] SET [Code] = @code WHERE [ID] = @id AND [Code] IS NULL How would I do the same check with Linqtosql? I assume I need to do a get and then set all the values and submit but what if someone updates [Code] to something other than null from the time I do the get to when the update executes? Same problem as the insert...

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