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Search found 1908 results on 77 pages for 'relational operators'.

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• Graph Theory: How to compute closeness centrality for each node in a set of data?

  - by Jordan

  I'd like to learn how to apply network theory to my own cache of relational data. I'm trying to build a demo of a new way of browsing a music library, using network theory, that I think would make for a very intuitive and useful way of finding the right song at any given time. I have all the data (artists as nodes, similarity from 0 to 1 between each artist and those it is related to) and I can already program, but I don't know how to actually calculate the centrality of a node from that. I've spent a while trying to email different professors at my school but no one seems to know where I can learn this. I hope someone's done something similar. Thanks in advance you guys! ~Jordan

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• Foreign key onto weak entity set in MS SQL Server 2008?

  - by Nic Waller

  I'm using Microsoft SQL Server 2008 Management Studio to create a relational schema by following an Entity-Relationship diagram. (included below; unrelated details removed) Until now, primary and foreign keys have been working as expected. But when I try to create a foreign key from the entity relationship takes onto the weak entity set section, I get an error. Section is identified by a composite primary key in the context of course, which has course_id as a primary key. Therefore, the primary key of section is a 4-way composite key. The entity relationship takes needs to refer to section, so it includes all 4 primary attributes from section in it's own primary key. When trying to establish a foreign key relationship from takes to section, Studio gives the following error: The columns in table 'section' do not match an existing primary key or UNIQUE constraint. Am I doing something wrong, or is this an unsupported configuration? I can provide more details or the SQL schema if necessary.

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• Entity LINQ on many-to-many got error "LINQ to Entities does not recognize the method 'Boolean Conta

  - by user300992

  I have 2 tables (Users and Roles) they are mapped as Many-to-Many in relational db. When I imported to Entity Data Content, they are still staying as the same relationship. Since they are mapped as Many-To-Many in Entity, I can access Users.RoleCollection or Roles.UserCollection However, when I execute this LINQ query, I got "LINQ to Entities does not recognize the method 'Boolean Contains... method, and this method cannot be translated into a store expression." var result (from a in Users from b in Roles where a.RoleCollection.Contains(b) select a); I think I must did something wrong... please help.

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• Fastest way to calculate an X-bit bitmask?

  - by Virtlink

  I have been trying to solve this problem for a while, but couldn't with just integer arithmetic and bitwise operators. However, I think its possible and it should be fairly easy. What am I missing? The problem: to get an integer value of arbitrary length (this is not relevant to the problem) with it's X least significant bits sets to 1 and the rest to 0. For example, given the number 31, I need to get an integer value which equals 0x7FFFFFFF (31 least significant bits are 1 and the rest zeros). Of course, using a loop OR-ing a shifted 1 to an integer X times will do the job. But that's not the solution I'm looking for. It should be more in the direction of (X << Y - 1), thus using no loops.

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• Microsoft SQL 2005 - using the modulo operator

  - by cc0

  So I have a silly problem, I have not used much MSSQL before, or any SQL for that matter. I basically have a minor mathematical problem that I need solved, and I thought modulo would be good. I have a number of dates in the database, but I need them be rounded off to the closest [dynamic integer] (could be anything from 0 to 5000000) which will be input as a parameter each time this query is called. So I thought I'd use modulo to find the remainder, then subtract that remainder from the date. If there is a better way, or an integrated function, please let me know! What would be the syntax for that? I've tried a lot of things, but I keep getting error messages like integers/floats/decimals can't be used with the modulo operators. I tried casting to all kinds of numeric datatypes. Any help would be appreciated.

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• Looking for evolutionary music example code

  - by Dan Dyer

  I would like to implement an interactive evolutionary algorithm for generating music (probably just simple melodies to start with). I'd like to use JFugue for this. Its website claims that it is well-suited to evolutionary music, but I can't find any evolutionary examples. I already have a framework to provide the evolutonary machinery. What I am looking for is some simple, working code that demonstrates viable approaches for the musical part (e.g. suitable encodings and evolutionary operators for the evolved tunes). I have some ideas how it might be achieved, but I'm not particularly knowledgeable about music theory, so to start with I'd like to just reimplement something that is known to work. So does anybody have, or know of, any freely available code (any language is fine) that demonstrates one or more approaches to evolutionary music? EDIT: I'm specifically looking for evolutionary code rather than other techniques that could be used for music synthesis.

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• GNU Flex, multiline rule

  - by Simone Margaritelli

  Hi there i have a flex rule inside my lexer definition : operators "[]"|"[]="|"[]<"|".."|"."|".="|"+"|"+="|"-"|"-="|"/"|"/="|"*"|"*="|"%"|"%="|"++"|"--"|"^"|"^="|"~"|"&"|"&="|"|"|"|="|"<<"|"<<="|">>"|"!"|"<"|">"|">="|"<="|"=="|"!="|"&&"|"||"|"~=" Is there any way to split this ruole on more lines to keep it clearer? I tried with \ just like macros but it does not seem to be accepted by flex :( PS: I don't want to split the rule in more sub-rules, but only split its regex in more lines to keep the code clearer.

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• Legal uses of setjmp and GCC

  - by Chris Lutz

  Using GCC (4.0 for me), is this legal: if(__builtin_expect(setjmp(buf) != 0, 1)) { // handle error } else { // do action } I found a discussion saying it caused a problem for GCC back in 2003, but I would imagine that they would have fixed it by now. The C standard says that it's illegal to use setjmp unless it's one of four conditions, the relevant one being this: one operand of a relational or equality operator with the other operand an integer constant expression, with the resulting expression being the entire controlling expression of a selection or iteration statement; But if this is a GCC extension, can I guarantee that it will work under for GCC, since it's already nonstandard functionality? I tested it and it seemed to work, though I don't know how much testing I'd have to do to actually break it. (I'm hiding the call to __builtin_expect behind a macro, which is defined as a no-op for non-GCC, so it would be perfectly legal for other compilers.)

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• given two bits in a set of four, fine position of two other bits

  - by aaa

  hello I am working on a simple combinatorics part, and found that I need to recover position of two bits given position of other two bits in 4-bits srring. for example, (0,1) maps to (2,3), (0,2) to (1,3), etc. for a total of six combinations. My solution is to test bits using four nested ternary operators: ab is a four bit string, with two bits set. c = ((((ab & 1) ? (((ab & 2) ? ... ))) : 0) abc = ab | c recover the last bit in the same fashion from abc. can you think of a better way/more clever way? thanks

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• Linq to SQL problem

  - by Ronnie Overby

  I have a local collection of recordId's (integers). I need to retrieve records that have every one of their child records' ids in that local collection. Here is my query: public List<int> OwnerIds { get; private set; } ... filteredPatches = from p in filteredPatches where OwnerIds.All(o => p.PatchesOwners.Select(x => x.OwnerId).Contains(o)) select p; I am getting this error: Local sequence cannot be used in Linq to SQL implementation of query operators except the Contains() operator. I get that .All() isn't supported by Linq to SQL, but is there a way to do what I am trying to do?

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• Is a switch statement the fastest way to implement operator interpretation in Java

  - by Mordan

  Is a switch statement the fastest way to implement operator interpretation in Java public boolean accept(final int op, int x, int val) { switch (op) { case OP_EQUAL: return x == val; case OP_BIGGER: return x > val; case OP_SMALLER: return x < val; default: return true; } } In this simple example, obviously yes. Now imagine you have 1000 operators. would it still be faster than a class hierarchy? Is there a threshold when a class hierarchy becomes more efficient in speed than a switch statement? (in memory obviously not) abstract class Op { abstract public boolean accept(int x, int val); } And then one class per operator.

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• How to Save custom DockWidgets

  - by Tobias

  Hello, I want to save my custom DockWidgets (inherited from QDockWidget) with the saveState() / restoreState() function my MainWindow provides. I have two questions: 1. How can I save and restore my Dockwidgets? - I already tried registering my custom DockWidgets as a QMetaType and implementing the default Constructor, copy Constructor, Destructor and Streaming operators. 2. How can I identify the loaded DockWidgets? - For example: If 2 DockWidgets where saved and I load them with restoreState(), is there a way to get pointers to these loaded Widgets? Thanks, Tobias

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• How to specify argument attributes in CFscript? (CF9)

  - by Henry

  In CF9 doc: Defining components and functions in CFScript, it says: /** *Comment text, treated as a hint. *Set metadata, including, optionally, attributes, in the last entries *in the comment block, as follows: *@metadataName metadataValue ... */ access returnType function functionName(arg1Type arg1Name="defaultValue1" arg1Attribute="attributeValue...,arg2Type arg2Name="defaultValue2" arg2Attribute="attributeValue...,...) functionAttributeName="attributeValue" ... { body contents } How do you specify arg1Attribute? I tried this: public void function setFirstname(string firstname="" displayName="first name"){} but it does NOT work. Also, how do you translate this to script-style? <cffunction name="setPerson"> <cfargument name="person" type="com.Person"/> </cffunction> I tried: function setPerson(com.Person person){} and it does NOT work either. "You cannot use a variable reference with "." operators in this context" it says.

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• Retrieving Data from SQL Server within Excel 2007

  - by Russell Giddings

  I have the following requirements I have relational content stored in a SQL Server 2005 database. I want to retrieve this data, transform it and display it in an Excel 2007 document. I would like this to be pulled from within Excel at the click of a button. As far as I can tell I have the following options... Create a view in Sql Server and reference it within a pivot table using a data connection. Create an Excel workbook using VSTO and create a web service which the workbook pulls data from Create a web service and use JScript with XMLHTTP request objects I currently only have a little experience of any of these methods (I'm very familiar with SQL Server although not pivot tables, I've created many web services although I've never used VSTO and I've used javascript extensively, but never in the context of Excel manipulation). Would you recommend one of the above approaches or is there a better way to do this?

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• Java bitshift strangeness

  - by Martin

  Java has 2 bitshift operators for right shifts: >> shifts right, and is dependant on the sign bit for the sign of the result >>> shifts right and shifts a zero into leftmost bits http://java.sun.com/docs/books/tutorial/java/nutsandbolts/op3.html This seems fairly simple, so can anyone explain to me why this code, when given a value of -128 for bar, produces a value of -2 for foo: byte foo = (byte)((bar & ((byte)-64)) >>> 6); What this is meant to do is take an 8bit byte, mask of the leftmost 2 bits, and shift them into the rightmost 2 bits. Ie: initial = 0b10000000 (-128) -64 = 0b11000000 initial & -64 = 0b10000000 0b10000000 >>> 6 = 0b00000010 The result actually is -2, which is 0b11111110 Ie. 1s rather than zeros are shifted into left positions

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• How to parse a string of boolean logic in PHP

  - by TheOddLinguist

  I'm building a PHP class with a private member function that returns a string value such as: 'true && true || false' to a public member function. (This string is the result of some regex matching and property lookups.) What I'd like to do is have PHP parse the returned logic and have the aforementioned public function return whether the boolean result of the parsed logic is true or false. I tried eval(), but I get no output at all. I tried typecasting the boolean returns...but there's no way to typecast operators...hehe Any ideas? (Let me know if you need more information.)

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• Operator overloading C++ outside class

  - by bobobobo

  Well, so there are 2 ways to overload operators for a C++ class INSIDE CLASS class Vector2 { public: float x, y ; Vector2 operator+( const Vector2 & other ) { Vector2 ans ; ans.x = x + other.x ; ans.y = y + other.y ; return ans ; } } ; OUTSIDE CLASS class Vector2 { public: float x, y ; } ; Vector2 operator+( const Vector2& v1, const Vector2& v2 ) { Vector2 ans ; ans.x = v1.x + v2.x ; ans.y = v1.y + v2.y ; return ans ; } In C# apparently you can only use the OUTSIDE class method The question is, in C++, which is "morer-correcter?" Which is preferable? When is one way better than another?

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• SQL SELECT: "Give me all documents where all of the documents procedures are 'work in progress'"

  - by prestonmarshall

  This one really has me stumped. I have a documents table which hold info about the documents, and a procedures table, which is kind of like a revisions table for each document. What I need to do is write a select statement which gives me all of the documents where all of the procedures have the status "work_in_progress". Here's an example procedures table: document_id | status 1 | 'wip' 1 | 'wip' 1 | 'wip' 1 | 'approved' 2 | 'wip' 2 | 'wip' 2 | 'wip' Here, I would want my query to only return document id 2, because all of its statuses are work_in_progress. I DO NOT want document_id 1 since one of its statuses is 'approved'. I believe this is relational division I want, but I'm not sure where to start. This is MySQL 5.0 FYI.

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• Comparing datafeeds from different networks (Affiliate Marketing)

  - by Logistetica

  Hi, I am working on integrating affiliate sales into few existing sites. We are using a few merchants who work via different networks (cj, shareasale, linkshare, avantlink). Now my observation is that all these networks provide data feeds in different formats. But that's not a big problem. My main concern is actually merchants using different titles on same products. I don't want to run into these situations: a) two listings of the SAME product from N merchants (if titles are just a bit different) b) one listing of N different products from merchants (if we don't use strict comparison algorithm) We want to automate everything as much as possible, want to avoid operators scanning listings under question all the time. How is this problem typically handled?

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• Suggest Cassandra data model for an existing schema

  - by Andriy Bohdan

  Hello guys! I hope there's someone who can help me suggest a suitable data model to be implemented using nosql database Apache Cassandra. More of than I need it to work under high loads and large amounts of data. Simplified I have 3 types of objects: Product Tag ProductTag Product: key - string key name - string .... - some other fields Tag: key - string key name - unique tag words ProductTag: product_key - foreign key referring to product tag_key - foreign key referring to tag rating - this is rating of tag for this product Each product may have 0 or many tags. Tag may be assigned to 1 or many products. Means relation between products and tags is many-to-many in terms of relational databases. Value of "rating" is updated "very" often. I need to be run the following queries Select objects by keys Select tags for product ordered by rating Select products by tag order by rating Update rating by product_key and tag_key The most important is to make these queries really fast on large amounts of data, considering that rating is constantly updated.

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• MDX performance vs. T-SQL

  - by SubPortal

  I have a database containing tables with more than 600 million records and a set of stored procedures that make complex search operations on the database. The performance of the stored procedures is so slow even with suitable indexes on the tables. The design of the database is a normal relational db design. I want to change the database design to be multidimensional and use the MDX queries instead of the traditional T-SQL queries but the question is: Is the MDX query better than the traditional T-SQL query with regard to performance? and if yes, to what extent will that improve the performance of the queries? Thanks for any help.

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• Sorting an array of Objective-c objects

  - by davbryn

  So I have a custom class Foo that has a number of members: @interface Foo : NSObject { NSString *title; BOOL taken; NSDate *dateCreated; } And in another class I have an NSMutableArray containing a list of these objects. I would very much like to sort this array based on the dateCreated property; I understand I could write my own sorter for this (iterate the array and rearrange based on the date) but I was wondering if there was a proper Objective-C way of achieving this? Some sort of sorting mechanism where I can provide the member variable to sort by would be great. In C++ I used to overload the < = operators and this allowed me to sort by object, but I have a funny feeling Objective-C might offer a nicer alternative? Many thanks

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• AJAX, PHP, XML, and cascading drop-down lists

  - by Dave Jarvis

  What PHP libraries would you recommend to implement the following: Three dependent drop-down lists Three XML data sources AJAX-based Essentially, I'd like to create an XML database and wire up a form that allows the user to select three different dependent parameters: User clicks Region User clicks District (filtered by Region) User clicks Station (filtered by District) Even though I would like to use PHP and XML, the general problem is: One XHTML form Three dependent, cascading drop-down lists Three flat files (no relational database) for the list data The solution must be efficient, simple, reliable, and cross-browser. What technologies would you recommend to solve the problem? Thank you!

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• Strategy Design Pattern -- *dynamic* !!!

  - by alexeypro

  My application will have different strategies for my objects. What's the best way of implementing that? I would really love the case when we can make strategy classes implementation dynamically loaded from, say, some relational database. Not sure how do that better, though. What's the best approach? Idea is that say we want to apply to object MyObj strategy Strategy123 then we just load from database by ID 123 the object, deserialize it, get the Strategy class, and use it with MyObj. The maintenance while sounds easier from the first look can be a pain in the long run if Strategy interfaces changes, etc. What can I do also? I want to find solution when I should be keeping Strategy classes in codebase -- just for the sake that I don't need code change and re-deployment of the application if my Strategy changes, or I add new strategy. Please advise!

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• How do I parse boolean logic?

  - by d03boy

  I need to write a boolean logic parser which will translate the boolean logic language to a SQL WHERE clause. The order of the operands will always be in the correct order (with value on the right). Here is a relatively simple example. There could be nested parentheses and the use of NOT operators, etc. (CACOUNT=01 OR CACOUNT=02 OR CACOUNT=03 OR CACOUNT=05 OR CACOUNT=07 OR CACOUNT=09 OR CACOUNT=12 OR CACOUNT=13 OR CACOUNT=18) AND Q4=1 AND NAME=TIMOTHY Here is what the WHERE clause would resemble. WHERE ( EXISTS ( SELECT 1 FROM MyVerticalTable b WHERE b.Key=a.Key AND b.Key='CACOUNT' AND b.Value='01' ) )

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