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• How to save an order (permutation) in an sql db

  - by Bendlas

  I have a tree structure in an sql table like so: CREATE TABLE containers ( container_id serial NOT NULL PRIMARY KEY, parent integer REFERENCES containers (container_id)) Now i want to define an ordering between nodes with the same parent. I Have thought of adding a node_index column, to ORDER BY, but that seem suboptimal, since that involves modifying the index of a lot of nodes when modifying the stucture. That could include adding, removing, reordering or moving nodes from some subtree to another. Is there a sql datatype for an ordered sequence, or an efficient way to emulate one? Doesn't need to be fully standard sql, I just need a solution for mssql and hopefully postgresql EDIT To make it clear, the ordering is arbitrary. Actually, the user will be able to drag'n'drop tree nodes in the GUI

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• Re-use aliased field in SQL SELECT STATEMENT

  - by Bad Display Name

  Hi, the question is hard to define without giving an example, e.g. I'd like to achieve something like this : SELECT (CASE WHEN ...) AS FieldA, 20 + FieldA AS FieldB FROM Tbl Assuming that by "..." I've replaced a long and complex CASE statement, hence I don't want to repeat it when selecting FieldB and use the aliased FieldA instead. IS THIS EVEN POSSIBLE? What could be a workaround? Note, that this will return multiple rows , hence the DECLARE/SET outside the SELECT statement is no good in my case. PLEASE HELP. P.S. I am using SQL 2008

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• How is push()ing and pop()ping defined?

  - by Helper Method

  I know how the push() and pop() methods in a typical implementation of a Queue/Linked List work but what I do want to know is what you actually define as a push or a pop? When can you name a method push()/pop()? What makes the insert()/add() method in a typical Tree implementation not a push()? My understanding is that push()ing means putting something to a position some special pointer is pointing to, and pop()ping an element means putting some object away some pointer is pointing to, but it doesn't seem to be clearly defined. Or does the naming matter at all?

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• Where should I set the DataContext - code behind or xaml?

  - by dovholuk

  (honestly I searched and read all the 'related questions' that seemed relevant - i do hope i didn't "miss" this question from elsewhere but here goes...) There are two different ways (at least) to set the DataContext. One can use XAML or one can use the code behind. What is the 'best practice' and why? I tend to favor setting it in XAML because it allows a designer to define collections on their own but I need 'ammunition' on why it's a best practice or why I'm crazy and the code behind is the bomb...

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• Ruby on Rails: Modules vs. Classes

  - by Jack

  I'm trying to add a function that will be accessible throughout all parts of my program. I want something like: def GlobalFunctions.my_function(x,y) puts x + y end to be accessible for all models. Specifically I am trying to use a function like this in my seeds.rb file but I am most likely going to be reusing the code and don't want any redundancy. Now I know I can make a simple class, but I could also make a module. What are some reasons to go in either direction? And once I've decided on which type to use, how do I make it accessible throughout the whole program? I have tried a module, but I keep getting " Expected app/[module file] to define [ModuleName]"

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• Is base method able to use derived base data members?

  - by iTayb

  Lets assume we have the following code: abstract class Base1 { protected int num; } class Der1:Base1 { protected Color color; protected string name; } class Der2:Base1 { protected DateTime dthen; } and so on. An array of base1 type exists and includes many objects created out of classes that are derived from base1. Is it possible to define the toString() method in the base class only? something like: public override string toString() { if (this is Der1) return "num = " + this.num + "color = " + this.color.toString() + " name = " this.name; if (this is Der2) return "num = " + this.num + "dthen = " + this.dthen.toString(); // and so on ... } Thank you very much :) P.S. This is not an homework question. I've just wondered about.

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• Offsite data storage for simple app, or a similar supported persistence mechanism?

  - by jdk

  Question Is there a usable facebook entry point to the Data Storage API that facebook lists on their app admin page for developers, or should I consider an alternate mechanism? What alternative mechanisms exist to simply persist my information offsite (away from my server app) without stuffing it into a cookie that's prone to expire? ... Background The facebook Data Store Admin tool is made available in a facebook App's Settings as seen here: (continue reading below) However when I visit the DataStoreAdmin link nothing works (i.e. clicking the buttons to define the data store types and objects does nothing - I have tried different browsers). The Wiki page for Data Store API hasn't been updated recently and the second last update says the beta Data Store was taken offline. It seems odd the link would be readily available and highly visible at the top of the App configuration area if indeed it's defunct. I was hoping some kind of key/value pair solution to remove the data calls from my own server.

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• How do you extend a Ruby module with macro-like metaprogramming methods?

  - by Ian Terrell

  Consider the following extension (the pattern popularized by several Rails plugins over the years): module Extension def self.included(recipient) recipient.extend ClassMethods recipient.class_eval { include InstanceMethods } end module ClassMethods def macro_method puts "Called macro_method within #{self.name}" end end module InstanceMethods def instance_method puts "Called instance_method within #{self.object_id}" end end end If you wished to expose this to every class, you can do the following: Object.send :include, Extension Now you can define any class and use the macro method: class FooClass macro_method end #=> Called macro_method within FooClass And instances can use the instance methods: FooClass.new.instance_method #=> Called instance_method within 2148182320 But even though Module.is_a?(Object), you cannot use the macro method in a module: module FooModule macro_method end #=> undefined local variable or method `macro_method' for FooModule:Module (NameError) This is true even if you explicitly include the original Extension into Module with Module.send(:include, Extension). How do you add macro like methods to Ruby modules?

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• Which HRESULT literal constant will fail the SUCCEEDED() macro?

  - by Hamish Grubijan

  Definition of SUCCEEDED(): #define SUCCEEDED(hr) (((HRESULT)(hr)) >= 0) Background: When an Ok button is clicked on a dialog, I need to return an HRESULT value hr such that SUCCEEDED(hr) is true. If Cancel button is clicked, I need to return a negative value. I could have used bools, but that would break the existing pattern (usually the hr values come from depths of system dlls). So, I know I can return S_OK on Ok, but what do I return on Cancel? I could just return (HRESULT)-1;, but there must be a better way - some HRESULT literal constant which has negative value and represents a generic failure. S_FALSE is not it, for it's value is defined as 1L. Please help me find the right constant.

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• Using iPhone Core Data to many Relationship

  - by BLeB

  When I define a to many relationship between entities in Xcode and then generate the data class from the entity I get a header with the following methods defined: @interface PriceList (CoreDataGeneratedAccessors) - (void)addItemsObject:(PriceListItem *)value; - (void)removeItemsObject:(PriceListItem *)value; - (void)addItems:(NSSet *)value; - (void)removeItems:(NSSet *)value; @end When I attempt to call addItemsObject with the following code a doesNotRecognizeSelector exception is thrown. PriceListItem *item = [NSEntityDescription insertNewObjectForEntityForName:@"PriceListItem" inManagedObjectContext:managedObjectContext]; item.cat = [attributeDict valueForKey:@"c"]; item.sel = [attributeDict valueForKey:@"s"]; [self addItemsObject:item]; From what I have read I do not have to implement these methods and that they are generated at runtime. Any ideas?

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• Javascript Inheritance and Arrays

  - by Inespe

  Hi all! I am trying to define a javascript class with an array property, and its subclass. The problem is that all instances of the subclass somehow "share" the array property: // class Test function Test() { this.array = []; this.number = 0; } Test.prototype.push = function() { this.array.push('hello'); this.number = 100; } // class Test2 : Test function Test2() { } Test2.prototype = new Test(); var a = new Test2(); a.push(); // push 'hello' into a.array var b = new Test2(); alert(b.number); // b.number is 0 - that's OK alert(b.array); // but b.array is containing 'hello' instead of being empty. why? As you can see I don't have this problem with primitive data types... Any suggestions?

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• What is CSS? what should be the shortest and appropriate answer of this question? [closed]

  - by metal-gear-solid

  What is CSS? what should be the shortest and appropriate answer of this question? How simple we can explain , What is CSS ,just in words? mine answer is this Stands for "Cascading Style Sheet." Cascading style sheets are used to format the layout of Web pages. They can be used to define text styles, table sizes, and other aspects of Web pages that previously could only be defined in a page's HTML. Is it ok or it can be more perfect or shorten?

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• How do I return the indices of a multidimensional array element in C?

  - by Eddy

  Say I have a 2D array of random boolean ones and zeroes called 'lattice', and I have a 1D array called 'list' which lists the addresses of all the zeroes in the 2D array. This is how the arrays are defined: define n 100 bool lattice[n][n]; bool *list[n*n]; After filling the lattice with ones and zeroes, I store the addresses of the zeroes in list: for(j = 0; j < n; j++) { for(i = 0; i < n; i++) { if(!lattice[i][j]) // if element = 0 { list[site_num] = &lattice[i][j]; // store address of zero site_num++; } } } How do I extract the x,y coordinates of each zero in the array? In other words, is there a way to return the indices of an array element through referring to its address?

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• Beginner's Question about accessing mysql using OOP

  - by user345690

  I am reading the PHP and mySQL web development book and so far been doing all the PHP and mysql using procedural. But then it talks about accessing mysql with objects. This works for me: //I define $db so can connect $query="select * FROM testing"; $result=mysqli_query($db,$query); while($row=mysqli_fetch_array($result)){ //echo the data } But when I try to do it with classes, it doesn't $query="select * FROM testing"; $result=$db->query($query); $row=$result->fetch_assoc(); Do I have to write my own class so it defines what query and fetch_assoc does? Or what?

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• Tools for understanding large codebase

  - by 0tar0gz

  Hi! My whole life I have been programming in simple plain text editor. Lately, I was contemplating about joining an open source project which is fairly large and written in C. I downloaded the sources, started to look around, read this, forget that... Then I thought to myself: this can't be true. This is 21st century there must be some tool which would help me to understand the code, perhaps some kind of IDE or "code navigator". What flows from here to where, this typedef struct is just interface to that private type, this function is just #define from above, function called in this file is defined in that file, ... you get the idea. Dear Stack Overflow, is this 21st century? Is there something like this?

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• Reduce text length to fit cell width in a smart manner

  - by Andrei Ciobanu

  Hello, I am in project where we are building a simple web calendar using Java EE technologies. We define a table where every row is an employee, and every column represents an hour interval. The table width and column widths are adjustable. In every cell we have a text retrieved from a database, indicating what the employee is doing / should do in that time interval. The problem is that sometimes the text in cells is getting bigger than the actual cell. My task is to make the text more "readable" by reducing it's length in a "smart way" so that it can fit in the cell more "gracefully". For example if initially in a cell I have: "Writing documents", after the resize I should retrieve: "Wrtng. dcmnts" or "Writ. docum." so that the text can fit well. Is there a smart way to do it ? Or removing vocals / split the string in two is enough ?

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• Mapping LINQ to SQL table to another very similar table without iterating through every one

  - by Daniel Coffman

  Apologies for the vague question. Here it is: I have a table object created by LINQ to SQL. I am copying entries from one table to an "archive" table that has all the columns of the original, plus a couple extra ones. It feels sloppy to iterate through every object and manually define the mapping like: foreach (oldTable in dbContextOldTables) { var newTable = new NewTable(); newTable.TableID = oldTable.ID; newTable.Title = oldTable.Title; ... (repeat for twenty columns) newTable.ColumnThatIsntInOldTable = "Data that will be the same for every row"; dbContext.NewTables.InsertOnSubmit(newTable); } dbContext.SubmitChanges(); Is there a clever way to do this?

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• What is the role of `while`-loops in computation expressions in F#?

  - by MizardX

  If you define a While method of the builder-object, you can use while-loops in your computation expressions. The signature of the While method is: member b.While (predicate:unit->bool, body:M<'a>) : M<'a> For comparison, the signature of the For method is: member b.For (items:seq<'a>, body:unit->M<'a>) : M<'a> You should notice that, in the While-method, the body is a simple type, and not a function as in the For method. You can embed some other statements, like let and function-calls inside your computation-expressions, but those can impossibly execute in a while-loop more than once. builder { while foo() do printfn "step" yield bar() } Why is the while-loop not executed more than once, but merely repeated? Why the significant difference from for-loops? Better yet, is there some intended strategy for using while-loops in computation-expressions?

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• SWIG interface file questions

  - by morpheous

  I am writing a C/C++ extension module for other languages and I am using SWIG to generate the bindings. I have two questions Can I include more than 1 header file in the declaration part of the interface file e.g.: /* Declarations exposed to wrapper: */ > %{ > #define SWIG_FILE_WITH_INIT > #include "a.h" > #include "b.h" > #include "c.h" %} In all of the examples I have seen so far, after the header include declaration (as shown above), the functions declared in the header are then declared again in the interface file. Is this really necessary, as it means there are two copies of the function declarations that need to be maintained. Note: I can appreciate that some functions/methods declaration may need to be 'decorated' with the 'newobject' declaration so these obviously need to be in the interface file, to avoid memory leaks - however, I would have though that it would be sufficient to include the headers and then ONLY the declarations of the functions/methods that need to be declared with 'newobject' - is this recommended way of doing things?

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• Rails 2.3.5: How does one access code inside of lib/directory/file.rb?

  - by randombits

  I created a file so I can share a method amongst many models in lib/foo/bar_woo.rb. Inside of bar_woo.rb I defined the following: module BarWoo def hello puts "hello" end end Then in my model I'm doing something like: def MyModel < ActiveRecord::Base include Foo::BarWoo def some_method Foo::BarWoo.hello end end The interpreter is complaining that it expected bar_woo.rb to define Foo::BarWoo. The Agile Web Development with Rails book states that if files contain classes or modules and the files are named using the lowercase form of the class or module name, then Rails will load the file automatically. I didn't require it because of this.

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• How do I map a macro across a list in Scheme?

  - by josh

  I have a Scheme macro and a long list, and I'd like to map the macro across the list, just as if it were a function. How can I do that using R5RS? The macro accepts several arguments: (mac a b c d) The list has (define my-list ((a1 b1 c1 d1) (a2 b2 c2 d2) ... (an bn cn dn))) And I'd like to have this: (begin (mac a1 b1 c1 d2) (mac a2 b2 c2 d2) ... (mac an bn cn dn)) (By the way, as you can see I'd like to splice the list of arguments too)

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• GetVolumeNameForVolumeMountPoint returns false

  - by new

  Hi.. To get the volume GUID i tried the code like below int len = wcslen( pDetData-DevicePath); pDetData-DevicePath[len] = '\'; pDetData-DevicePath[len+1] = 0; define BUFFER_SIZE MAX_PATH WCHAR volume[BUFFER_SIZE]; BOOL bFlag; bFlag = GetVolumeNameForVolumeMountPoint( pDetData-DevicePath, volume, BUFFER_SIZE ); int loginErrCode = GetLastError(); printf("loginErrCode: %d\n", loginErrCode); printf("BFLAG: %d\n", bFlag); the GetLastError() also prints it as 1 . it means ERROR_INVALID_FUNCTION the bFlag always returns zero it means false. what is the problem in my code... please help me up to get the above function work right

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• How to serialize this Xml in .NET (array)

  - by Morri

  I need Xml that looks like this <foo> <bar ... /> <bar ... /> </foo> And currently have the following class structure : [XmlRoot("foo")] public class Foo { [XmlArrayItem("bar")] public List<Bar> myBars; } But this gives me Xml where bar items are wrapped inside a bars element. How should I define my custom XmlAttributes so I'd get the Xml structure I need?

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• refresh a <ui:composition when j_security_check connection interrupted (http 408)

  - by José Osuna Barrios

  I have a "j_security_check connection interrupted (http code 408)" and proposed solution is <meta http-equiv="refresh" content="#{session.maxInactiveInterval}"/> by http://stackoverflow.com/a/2141274/1852036 but my page structure is a composition using a template.xhtml and a view.xhtml like a <ui:composition: my template.xhtml: <html ... <f:view ... <h:body ... <ui:insert name="content"> ... my view.xhtml to refresh when session.maxInactiveInterval <ui:composition ... <ui:define name="content"> ... may anyone help me to do this? I want to refresh this <ui:composition view, I can't use <meta http-equiv="refresh" content="#{session.maxInactiveInterval}"/> on template.xhtml because it's used by several views

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• [Perl] Use a Module / Object which is defined in the same file

  - by Robert S. Barnes

  I need to define some modules and use them all in the same file. No, I can't change the requirement. I would like to do something like the following: { package FooObj; sub new { ... } sub add_data { ... } } { package BarObj; use FooObj; sub new { ... # BarObj "has a" FooObj my $self = ( myFoo => FooObj->new() ); ... } sub some_method { ... } } my $bar = BarObj->new(); However, this results in the message: Can't locate FooObj.pm in @INC ... BEGIN failed... How do I get this to work?

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