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  • move data from one table to another, postgresql edition

    - by IggShaman
    Hi All, I'd like to move some data from one table to another (with a possibly different schema). Straightforward solution that comes into mind is - start a transaction with serializable isolation level; INSERT INTO dest_table SELECT data FROM orig_table,other-tables WHERE <condition>; DELETE FROM orig_table USING other-tables WHERE <condition>; COMMIT; Now what if the amount of data is rather big, and the <condition> is expensive to compute? In PostgreSQL, a RULE or a stored procedure can be used to delete data on the fly, evaluating condition only once. Which solution is better? Are there other options?

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  • asp.net mvc 2 multithread

    - by Chris Cap
    I'm getting some weird behavior in asp.net MVC2 (at least it's not what I'm expecting). I have a controller httppost action that processes credit cards. I'm setting a session variable on the server to let me know if a user has attempted to process a card. I clear that session variable when I'm done. I am doing some very quick posts to test the process and the session variable is coming back null everytime because I clear the session variable at the end of the process. I have some debug prints that show me that the all requests are processed synchronously. That is...the first attempt occurs, it fails, session variable is cleared, second attempt tries and fails and the variable is cleared, etc... My first thought was that this was a side effect of debugging and that it just lined requests up for debugging purposes using the local webserver. So I put it on a development server and the same thing is occurring. Multiple submits/posts are processed synchronously. I even put a System.Threading.Sleep in there to make sure it would stop right after I set the session variable and it still won't even START the second request until the first is done. Has anyone else seen this behavior? My understanding was that a worker process was spawned for each request and that these actions could happen asychronously. Here's some psuedo code if (Session["CardCharged"] != null) return RedirectToAction("Index", "Problem"); Session["CardCharged"] = false; //starting the process System.Threading.Thread.Sleep(10000); //charge card here if (!providerResponse.IsApproved) { System.Diagnostics.Debug.WriteLine("failed"); Session["CardCharged"] = null; //have to allow them to charge again since this failed return View(myModel); } Session["CardCharged"] = true; return RedirectToAction("Index", "OrderComplete"); I should mention that my code ALWAYS fails the credit card check for testing purposes. I'm trying to test the situation where processing is STILL occurring and redirect the user elsewhere. I have set a dummy session variable elsewhere to assure that the session id "sticks". So I know the session id is the same for each request. Thanks

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  • How do I add an object to a binary tree based on the value of a member variable?

    - by Max
    How can I get a specific value from an object? I'm trying to get a value of an instance for eg. ListOfPpl newListOfPpl = new ListOfPpl(id, name, age); Object item = newListOfPpl; How can I get a value of name from an Object item?? Even if it is easy or does not interest you can anyone help me?? Edited: I was trying to build a binary tree contains the node of ListOfPpl, and need to sort it in the lexicographic. Here's my code for insertion on the node. Any clue?? public void insert(Object item){ Node current = root; Node follow = null; if(!isEmpty()){ root = new Node(item, null, null); return; }boolean left = false, right = false; while(current != null){ follow = current; left = false; right = false; //I need to compare and sort it if(item.compareTo(current.getFighter()) < 0){ current = current.getLeft(); left = true; }else { current = current.getRight(); right = true; } }if(left) follow.setLeft(new Node(item, null, null)); else follow.setRight(new Node(item, null, null)); }

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  • How do I write a writer method for a class variable in Ruby?

    - by tepidsam
    I'm studying Ruby and my brain just froze. In the following code, how would I write the class writer method for 'self.total_people'? I'm trying to 'count' the number of instances of the class 'Person'. class Person attr_accessor :name, :age @@nationalities = ['French', 'American', 'Colombian', 'Japanese', 'Russian', 'Peruvian'] @@current_people = [] @@total_people = 0 def self.nationalities #reader @@nationalities end def self.nationalities=(array=[]) #writer @@nationalities = array end def self.current_people #reader @@current_people end def self.total_people #reader @@total_people end def self.total_people #writer #-----????? end def self.create_with_attributes(name, age) person = self.new(name) person.age = age person.name = name return person end def initialize(name="Bob", age=0) @name = name @age = age puts "A new person has been instantiated." @@total_people =+ 1 @@current_people << self end

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  • Why "constructor-way" of declaring variable in "for-loop" allowed but in "if-statement" not allowed?

    - by PiotrNycz
    Consider this simple example: /*1*/ int main() { /*2*/ for (int i(7); i;){break;} /*3*/ if (int i(7)) {} /*4*/ } Why line-2 compiles just fine, whilst line-3 gives the error? This is little strange to me why if-statement is in this aspect treated worse than for-loop? If this is compiler specific - I tested with gcc-4.5.1: prog.cpp: In function 'int main()': prog.cpp:3:7: error: expected primary-expression before 'int' prog.cpp:3:7: error: expected ')' before 'int' I was inspired by this question [UPDATE] I know this compiles just fine: /*1*/ int main() { /*2*/ for (int i = 7; i;){break;} /*3*/ if (int i = 7) {} /*4*/ }

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  • Wouldn't it be nice to have a type variable referring to the class's instance.

    - by user93197
    I often have a pattern like this: class VectorBase<SubClass, Element> where SubClass : VectorBase<SubClass, Element>, new() where Element : Addable<Element> { Element[] data; public VectorBase(Element[] data) { this.data = data; } public SubClass add(SubClass second) { Element[] newData = new Element[data.Length]; for (int i = 0; i < newData.Length; i++) { newData[i] = data[i].add(second.data[i]); } SubClass result = new SubClass(); result.data = newData; return result; } } class VectorInt : VectorBase<VectorInt, Int32> { } class MyInt : Addable<MyInt> { int data; public MyInt(int data) { this.data = data; } public MyInt add(MyInt t) { return new MyInt(data + t.data); } } interface Addable<T> { T add(T t); } But I would rather just have: class VectorBase2<Element> where Element : Addable<Element> { Element[] data; public VectorBase(Element[] data) { this.data = data; } public SubClass add(SubClass second) { Element[] newData = new Element[data.Length]; for (int i = 0; i < newData.Length; i++) { newData[i] = data[i].add(second.data[i]); } SubClass result = new SubClass(data); return result; } } class VectorInt2 : VectorBase2<Int32> { } Why not make the subclass type available to all classes? Is this technically impossible?

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  • What is wrong in this simple Makefile

    - by Walidix
    SRC_VAR = test string for variable manipulation. TEST1_VAR = $(subset for,foo,${SRC_VAR}) all: @echo original str: ${SRC_VAR} @echo substitution: ${TEST1_VAR} This is the output: original str: test string for variable manipulation. substitution: The output should be: original str: My test string for variable manipulation. substitution: My test string foo variable manipulation.

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  • How can i use a variable created in a objective c Void function?

    - by James
    Im trying to get the lat and long values generated in a void function and use them within another function. Any help grateful. (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { float latDeg = newLocation.coordinate.latitude; NSLog(@"Lat: %g", latDeg); float longDeg = newLocation.coordinate.longitude; NSLog(@"Lat: %g", longDeg); } I want to use the latDeg and longDeg variables.

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  • How to pass an integer to create new variable name?

    - by Joe
    I have 50 svg animations named animation0, animation1, animation2 etc. and I want to load them when the integer 0 to 49 is passed to this function: function loadAnimation(value){ var whichswiffy = "animation" + value; var stage = new swiffy.Stage(document.getElementById('swiffycontainer'), whichswiffy); stage.start(); } It doesn't work at the moment, maybe it's passing 'whichswiffy' rather than 'animation10'? Any ideas?

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  • How to declare a pointer to a variable as a parameter of a function in C++?

    - by Keand64
    I have a function that takes a pointer to a D3DXVECTOR3, but I have no reason to declare this beforehand. The most logical solution to me was using new: Function( //other parameters, new D3DXVECTOR3(x, y, 0)); but I don't know how I would go about deleting it, beign intitialized in a function. My next thought was to use the & operator, like so: Function( //other parameters, &D3DVECTOR3(x, y, 0)); but I don't know if this is a valid way to go about doing this. (It doesn't get an error, but neither does int *x; x = 50;). So should I use new, &, or some other technique I'm overlooking?

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  • Can I execute a "variable statements" within a function and without defines.

    - by René Nyffenegger
    I am facing a problem that I cannot see how it is solvable without #defines or incuring a performance impact although I am sure that someone can point me to a solution. I have an algorithm that sort of produces a (large) series of values. For simplicity's sake, in the following I pretend it's a for loop in a for loop, although in my code it's more complex than that. In the core of the loop I need to do calculations with the values being produced. Although the algorithm for the values stays the same, the calculations vary. So basically, what I have is: void normal() { // "Algorithm" producing numbers (x and y): for (int x=0 ; x<1000 ; x++) { for (int y=0 ; y<1000 ; y++) { // Calculation with numbers being produced: if ( x+y == 800 && y > 790) { std::cout << x << ", " << y << std::endl; } // end of calculation }} } So, the only part I need to change is if ( x+y == 800 && y > 790) { std::cout << x << ", " << y << std::endl; } So, in order to solve that, I could construct an abstract base class: class inner_0 { public: virtual void call(int x, int y) = 0; }; and derive a "callable" class from it: class inner : public inner_0 { public: virtual void call(int x, int y) { if ( x+y == 800 && y > 790) { std::cout << x << ", " << y << std::endl; } } }; I can then pass an instance of the class to the "algorithm" like so: void O(inner i) { for (int x=0 ; x<1000 ; x++) { for (int y=0 ; y<1000 ; y++) { i.call(x,y); }} } // somewhere else.... inner I; O(I); In my case, I incur a performance hit because there is an indirect call via virtual function table. So I was thinking about a way around it. It's possible with two #defines: #define OUTER \ for (int x=0 ; x<1000 ; x++) { \ for (int y=0 ; y<1000 ; y++) { \ INNER \ }} // later... #define INNER \ if (x + y == 800 && y > 790) \ std::cout << x << ", " << y << std::endl; OUTER While this certainly works, I am not 100% happy with it because I don't necessarly like #defines. So, my question: is there a better way for what I want to achieve?

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  • Is there a straightforward way to have a thread-local instance variable?

    - by Dan Tao
    With the ThreadStatic attribute I can have a static member of a class with one instance of the object per thread. This is really handy for achieving thread safety using types of objects that don't guarantee thread-safe instance methods (e.g., System.Random). It only works for static members, though. Is there any straightforward way to declare a class member as thread-local, meaning, each class instance gets an object per thread?

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  • What is the most "database independent" way of creating a variable length text field in a database

    - by Thibaut Colar
    I want to create a text field in the database, with no specific size (it will store text of length unknown in some case) - the particular text are serialized simple object (~ JSON) What is the most database independent way to do this : - a varchar with no size specified (don't think all db support this) - a 'text' field, this seems to be common, but I don't believe it's a standard - a blob or other object of that kind ? - a varchar of a a very large size (that's inefficient and wastes disk space probably) - Other ? I'm using JDBC, but I'd like to use something that is supported in most DB (oracle, mysql, postgresql, derby, HSQL, H2 etc...) Thanks.

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  • What are possible suffixes after variable name in VBA?

    - by archimed7592
    As I've already figured out, there is at least six of them: !@#$%&. Here is snip: Dim A!, B@, C#, D$, E%, F& Debug.Print "A! - " & TypeName(A) Debug.Print "B@ - " & TypeName(B) Debug.Print "C# - " & TypeName(C) Debug.Print "D$ - " & TypeName(D) Debug.Print "E% - " & TypeName(E) Debug.Print "F& - " & TypeName(F) Outputs A! - Single B@ - Currency C# - Double D$ - String E% - Integer F& - Long Where is documentation on this syntax sugar? What other possible suffixes are there? Is there one for Date?

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  • jQuery: Quick question. How to select string variable?

    - by user317563
    Hello world, EDIT: I would like to avoid doing something like this: var str = 'Hello'; if ( str == 'Hello') { alert(str); } I would rather do: var str = 'Hello'; $(str).filter(':contains("Hello")').each(function(){ alert(this) }); I've tried a lot of things: $(str).text().method1().method2().method3(); $(str).val().method1().method2().method3(); $(str).contents().method1().method2().method3(); Nothing worked. Is it possible to do this? Thank you for your time. Kind regards, Marius

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  • How can I draw a line with a variable of width?

    - by user1729944
    #include <iostream> #include <cmath> #include "graph1.h" using namespace std; int main() { int diameter = 0; int height = 0; double rate = 0; char repeat = 'y'; int obj_num = 0; displayGraphics(); obj_num = drawRect(0,0,50,400); setColor(obj_num,200,200,200); obj_num = drawRect(0,400,640,79); setColor(obj_num,71,35,35); obj_num = drawLine(50,50,150,50,5); setColor(obj_num,80,80,80); displayBMP("faucet.bmp",150,12); do { do { cout << "Enter the diamater of the cylinder <in inches > 0 but <= 300: "; cin >> diameter; if((diameter<0) || (diameter>300)) { cout << "Incorrect diamater entered; value must be between 1 and 300" << endl; } }while((diameter<0) || (diameter>300)); do { cout << "Enter the height of the cylinder <in inches > 0 but <= 325: "; cin >> height; if((height<0) || (height>325)) { cout << "Incorrect height entered; value must be between 1 and 325" << endl; } }while((height<0) || (height>325)); do { cout << "Enter the facet water's rate: <gallons/minute> "; cin >> rate; if((rate<0) || (rate>100)) { cout << "Incorrect rate entered; value must be between 1 and 100" << endl; } }while((rate<0) || (rate>100)); //I need to draw the lines here. The graphics window has a faucet that is supposed to fill //up a cylinder made out of 3 lines. I don't know how to make the lines vary from the users //input since lines are hard coded with points and all i am receiving is the width for the //bottom line and the height for the left and right lines. cout << "Repeat program? (y/n): "; cin >> repeat; clearGraphics(); }while ( (repeat == 'y') || (repeat == 'Y') ); return 0; } Here is a screenshot for reference:

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