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  • Aggregate functions in ANSI SQL

    - by morpheous
    I want to use multiple aggregate functions in a query. All the examples i have seem on aggregate functions however, are trivial. Typically, they are of the form: SELECT field1,agg_func1, agg_func2 GROUP BY SOME_COLUMNS HAVING agg_func1 OP SOME_SCALAR Where: OP: is a boolean operator (e.g. <, = etc) SOME_SCALAR: is a scalar (i.e. a constant number) What I want to know is if it is possible to write (IN ANSI SQL) queries like: SELECT field1,agg_func1, agg_func2, agg_func3 GROUP BY SOME_COLUMNS HAVING (agg_func1 OP1 agg_func2) OP2 (agg_func2 OP3 agg_func3) Where: OP[N] are boolean operators or ANSI SQL clause operators like 'BETWEEN', 'LIKE', 'IN' etc. Also, assuming this is possible (I have not seen any documentation saying otherwise) are there any efficiency/performance considerations (i.e. penalties) when the HAVING clause consists of a boolean expression combining the output of the aggregate functions - instead of the normal comparison of the output of the aggregate with a constant number (e.g. min('salary') 100 ) - which is often used in the most banal examples involving aggregate functions?

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  • Binning into timeslots - Is there a better way than using list comp?

    - by flyingcrab
    I have a dataset of events (tweets to be specific) that I am trying to bin / discretize. The following code seems to work fine so far (assuming 100 bins): HOUR = timedelta(hours=1) start = datetime.datetime(2009,01,01) z = [dt + x*HOUR for x in xrange(1, 100)] But then, I came across this fateful line at python docs 'This makes possible an idiom for clustering a data series into n-length groups using zip(*[iter(s)]*n)'. The zip idiom does indeed work - but I can't understand how (what is the * operator for instance?). How could I use to make my code prettier? I'm guessing this means I should make a generator / iterable for time that yields the time in graduations of an HOUR?

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  • How can I pull data from a SQL Database that spans an academic year?

    - by Eric Reynolds
    Basically, I want to pull data from August to May for a given set of dates. Using the between operator works as long as I do not cross the year marker (i.e. BETWEEN 8 AND 12 works -- BETWEEN 8 AND 5 does not). Is there any way to pull this data? Here is the SQL Query I wrote: SELECT count(*), MONTH(DateTime) FROM Downloads WHERE YEAR(DateTime) BETWEEN 2009 AND 2010 AND MONTH(DateTime) BETWEEN 8 AND 5 GROUP BY MONTH(DateTime) ORDER BY MONTH(DateTime)" Any help is appreciated. Thanks, Eric R.

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  • JavaScript Regex: Complicated input validation

    - by ScottSEA
    I'm trying to construct a regex to screen valid part and/or serial numbers in combination, with ranges. A valid part number is a two alpha, three digit pattern or /[A-z]{2}\d{3}/ i.e. aa123 or ZZ443 etc... A valid serial number is a five digit pattern, or /\d{5}/ 13245 or 31234 and so on. That part isn't the problem. I want combinations and ranges to be valid as well: 12345, ab123,ab234-ab245, 12346 - 12349 - the ultimate goal. Ranges and/or series of part and/or serial numbers in any combination. Note that spaces are optional when specifying a range or after a comma in a series. Note that a range of part numbers has the same two letter combination on both sides of the range (i.e. ab123 - ab239) I have been wrestling with this expression for two days now, and haven't come up with anything better than this: /^(?:[A-z]{2}\d{3}[, ]*)|(?:\d{5}[, ]*)|(?:([A-z]{2})\d{3} ?- ?\4\d{3}[, ]*)|(?:\d{5} ?- ?\d{5}[, ]*)$/ ... My Regex-Fu is weak.

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  • How Serializable works with insert in SQL Server 2005

    - by Spence
    G'day I think I have a misunderstanding of serializable. I have two tables (data, transaction) which I insert information into in a serializable transaction (either they are both in, or both out, but not in limbo). SET TRANSACTION ISOLATION LEVEL SERIALIZABLE BEGIN TRANSACTION INSERT INTO dbo.data (ID, data) VALUES (@Id, data) INSERT INTO dbo.transactions(ID, info) VALUES (@ID, @info) COMMIT TRANSACTION I have a reconcile query which checks the data table for entries where there is no transaction at read committed isolation level. INSERT INTO reconciles (ReconcileID, DataID) SELECT Reconcile = @ReconcileID, ID FROM Data WHERE NOT EXISTS (SELECT 1 FROM TRANSACTIONS WHERE data.id = transactions.id) Note that the ID is actually a composite (2 column) key, so I can't use a NOT IN operator My understanding was that the second query would exclude any values written into data without their transaction as this insert was happening at serializable and the read was occurring at read committed. I have evidence that reconcile is picking up entries

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  • LINQ-to-SQL: Searching against a CSV

    - by Peter Bridger
    I'm using LINQtoSQL and I want to return a list of matching records for a CSV contains a list of IDs to match. The following code is my starting point, having turned a CSV string in a string array, then into a generic list (which I thought LINQ would like) - but it doesn't: Error Error 22 Operator '==' cannot be applied to operands of type 'int' and 'System.Collections.Generic.List<int>' C:\Documents and Settings\....\Search.cs 41 42 C:\...\ Code DataContext db = new DataContext(); List<int> geographyList = new List<int>( Convert.ToInt32(geography.Split(',')) ); var geographyMatches = from cg in db.ContactGeographies where cg.GeographyId == geographyList select new { cg.ContactId }; Where do I go from here?

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  • Is this a correct implementation of singleton C++?

    - by Kamal
    class A{ static boost::shared_ptr<A> getInstance(){ if(pA==NULL){ pA = new A(); } return boost::shared_ptr(pA); } //destructor ~A(){ delete pA; pA=NULL; } private: A(){ //some initialization code } //private assigment and copy constructors A(A const& copy); // Not Implemented A& operator=(A const& copy); // Not Implemented static A* pA; }; A* A::pA = NULL;

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  • Lazy evaluation with ostream C++ operators

    - by SavinG
    I am looking for a portable way to implement lazy evaluation in C++ for logging class. Let's say that I have a simple logging function like void syslog(int priority, const char *format, ...); then in syslog() function we can do: if (priority < current_priority) return; so we never actually call the formatting function (sprintf). On the other hand, if we use logging stream like log << LOG_NOTICE << "test " << 123; all the formating is always executed, which may take a lot of time. Is there any possibility to actually use all the goodies of ostream (like custom << operator for classes, type safety, elegant syntax...) in a way that the formating is executed AFTER the logging level is checked ?

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  • is this a simple monad example?

    - by zcaudate
    This is my attempt to grok monadic functions after watching http://channel9.msdn.com/Shows/Going+Deep/Brian-Beckman-Dont-fear-the-Monads. h uses bind to compose together two arbitrary functions f and g. What is the unit operator in this case? ;; f :: int - [str] ;; g :: str = [keyword] ;; bind :: [str] - (str - [keyword]) - [keyword] ;; h :: int - [keyword] (defn f [v] (map str (range v))) (defn g [s] (map keyword (repeat 4 s))) (defn bind [l f] (flatten (map f l))) (f 8) ;; = (0 1 2 3 4 5 6 7) (g "s") ;; = (:s :s :s :s) (defn h [v] (bind (f v) g)) (h 9) ;; = (:0 :0 :0 :0 :1 :1 :1 :1 :2 :2 :2 :2 :3 :3 :3 :3 :4 :4 :4 :4 :5 :5 :5 :5)

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  • NASM shift operators

    - by Hudson Worden
    How would you go about doing a bit shift in NASM on a register? I read the manual and it only seems to mention these operators , <<. When I try to use them NASM complains about the shift operator working on scalar values. Can you explain what a scalar value is and give an example of how to use and <<. Also, I thought there were a shr or shl operators. If they do exist can you give an example of how to use them? Thank you for your time.

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  • What is Ruby's double-colon (::) all about?

    - by Meltemi
    I'd probably be able to answer this for myself if "::" wasn't so hard to Google. Didn't see anything on SO so thought I'd try my luck. What is this double-colon :: all about? I see it everywhere in Rails: class User < ActiveRecord::Base or… ActionController::Routing::Routes.draw do |map| I found a definition from this guy: The :: is a unary operator that allows: constants, instance methods and class methods defined within a class or module, to be accessed from anywhere outside the class or module. but that just leads to more questions. What good is scope (private, protected) if you can just use :: to expose anything?

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  • How to use a object whose copy constructor and copy assignment is private?

    - by coanor
    In reading TCPL, I got a problem, as the title refered, and then 'private' class is: class Unique_handle { private: Unique_handle& operator=(const Unique_handle &rhs); Unique_handle(const Unique_handle &rhs); public: //... }; the using code is: struct Y { //... Unique_handle obj; }; and I want to execute such operations: int main() { Y y1; Y y2 = y1; } although, these code are come from TCPL, but I still can not got the solution... Can anybody help me, appreciate.

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  • AspectJ join point with simple types

    - by Jon
    Hi! Are there defined join points in arithmetics that I can catch? Something like: int a = 4; int b = 2; int c = a + b; Can I make a pointcut that catches any one of those lines? And what context will I be able to get? I would like to add a before() to all int/float/double manipulation done in a particular method on a class, is that possible. I see in the AspectJ docs that there are defined join points for object initialization and method calls. Is declaring an int an object initialization and does the + operator count as a method call? Thanks!

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  • HASHREF in Perl

    - by Uri
    I'm trying to decrypt a Perl code which I'm not familiar with, somehow related to HashRef. I'm using Amazon::S3, but my question is a general Perl question. See the code below: use Amazon::S3; my $s3 = Amazon::S3-new( ... ); my $response = $s3-buckets; Documentation (here) sais, about s3-buckets: Returns undef on error, else HASHREF of results The following line is working for me, but I don't understand why: for $b in ( @ { $response-{buckets} } ) { print "bucket: " . $b-bucket . "\n"; } I'm buzzled by each operator on the first line. What type exactly are $response, $respone-{bucket}. Looks like the expression within the 'for' is an array, but I don't understand this syntax: @{ ... }?

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  • What are the differences between these three patterns of "class" definitions in JavaScript?

    - by user1889765
    Are there any important/subtle/significant differences under the hood when choosing to use one of these three patterns over the others? And, are there any differences between the three when "instantiated" via Object.create() vs the new operator? The pattern that CoffeeScript uses when translating "class" definitions: Animal = (function() { function Animal(name) { this.name = name; } Animal.prototype.move = function(meters) { return alert(this.name + (" moved " + meters + "m.")); }; return Animal; })(); and The pattern that Knockout seems to promote: var DifferentAnimal = function(name){ var self = this; self.name = name; self.move = function(meters){ return alert(this.name + (" moved " + meters + "m.")); }; return {name:self.name, move:self.move}; } and The pattern that Backbone promotes: var OneMoreAnimal= ClassThatAlreadyExists.extend({ name:'', move:function(){} });

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  • drupal themes: how do I include several css files / js files on my theme's .info file?

    - by egarcia
    I'm creating a new Drupal theme. Until now, I only needed to include a single css file and a single js file. So my theme.info file had something like this: stylesheets[all][] = css/style.css scripts[] = js/script.js Now I must include jquery and jquery-ui in order to use a calendar date. These come with 2 new javascript files, and 1 additonal css file that I must add to the site. The calendar input form is going to be used in all pages (on a side block) so it is ok for me to load the extra css/javascript on all pages. I think the easiest thing would be to reference them on the .info file itself. At first I tried to just put them there with separate spaces: stylesheets[all][] = css/style.css css/ui-lightness/jquery-ui-1.8.1.custom.css scripts[] = js/script.js js/jquery-1.4.2.min.js js/jquery-ui-1.8.1.custom.min.js I emptied drupal's cache and... none of them loaded. I then tried separating each file with a comma, and flushing the cache again. Same result. I've browsed some drupal pages, but could not find how to add several javascript/css files on one theme (they always seem to add just 1 of each). So, how do I include several css/javascript files on the .info file?

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  • On Memory Allocation and C++

    - by Arpan
    And I quote from MSDN http://msdn.microsoft.com/en-us/library/aa366533(VS.85).aspx: The malloc function has the disadvantage of being run-time dependent. The new operator has the disadvantage of being compiler dependent and language dependent. Now the questions folks: a) What do we mean that malloc is run-time dependent? What kind of dynamic memory allocation functions can be independent of run-time? This statement sounds real strange. b) new is language dependent? Of course it should be right? Are HeapAlloc, LocalAlloc etc language independent? c) From a pure performance perspective are the MSVC provided routines preferable? Arpan

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  • Getting batch_action functionality in Symfony 1.0

    - by Alex Ciminian
    I'm currently working on a web app written in Symfony. I'm supposed to add an "export to CSV" feature in the backend/administration part of the app for some modules. In the list view, there should be an "Export" button which should provide the user with a csv file of the elements that are displayed (considering filtering criteria). I've created a method in the actions class of the module that takes a comma separated list of ids and generates the CSV, but I'm not really sure how to add the link to it in the view. The problem is that the view doesn't exist anywhere, it's generated on the fly from the data in the generator.yml configuration file. I've posted the relevant part of the file below. I'm new to Symfony, so any help would be appreciated :). Thanks, Alex Update list: display: [id, =name, indemn, _status, _participants, _approved_, created_at] title: Lista actiuni object_actions: _edit: ~ _delete: ~ actions: _create: ~ export_csv: name: Export to CSV action: CSVExport params: id=csvActionSubmit filters: [name, county_id, _status_filter, activity_id] fields: id: name: Nr. crt. ... Thanks to your advice, I've managed to add a button that is linked to my action. The problem is that I also need to send some parameters to the action, because I may not want all the elements - filters may have been used. Unfortunately, the project is using Symfony 1.0, which doesn't support batch_actions. Currently, I'm working around this with Javascript (I parse the DOM to get the numeric ids (from the display table) and then build the link for the button. I really think there could be a better way for this.

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  • CUDA & VS2010 problem

    - by Kristian D'Amato
    I have scoured the internets looking for an answer to this one, but couldn't find any. I've installed the CUDA 3.2 SDK (and, just now, CUDA 4.0 RC) and everything seems to work fine after long hours of fooling around with include directories, NSight, and all the rest. Well, except this one thing: it keeps highlighting the <<< >>> operator as a mistake. Only on VS2010--not on VS2008. On VS2010 I also get several warnings of the following sort: C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xdebug(109): warning C4251: 'std::_String_val<_Ty,_Alloc>::_Alval' : class 'std::_DebugHeapAllocator<_Ty>' needs to have dll-interface to be used by clients of class 'std::_String_val<_Ty,_Alloc>' Anyone know how this can be fixed?

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  • Forcing a templated object to construct from a pointer

    - by SalamiArmi
    I have a fictional class: template<typename T> class demonstration { public: demonstration(){} ... T *m_data; } At some point in the program's execution, I want to set m_data to a big block of allocated memory and construct an object T there. At the moment, I've been using this code: void construct() { *m_data = T(); } Which I've now realised is probably not the best idea... wont work under certain cirumstances, if T has a private assignment operator for example. Is there a normal/better way to do what I'm attempting here?

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  • Multiset of shared_ptrs as a dynamic priority queue: Concept and practice

    - by Sarah
    I was using a vector-based priority queue typedef std::priority_queue< Event, vector< Event >, std::greater< Event > > EventPQ; to manage my Event objects. Now my simulation has to be able to find and delete certain Event objects not at the top of the queue. I'd like to know if my planned work-around can do what I need it to, and if I have the syntax right. I'd also like to know if dramatically better solutions exist. My plan is to make EventPQ a multiset of smart pointers to Event objects: typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; I'm borrowing functions of the Event class from a related post on a multimap priority queue. // Event.h #include <cstdlib> using namespace std; #include <set> #include <boost/shared_ptr.hpp> class Event; typedef std::multi_set< boost::shared_ptr< Event > > EventPQ; class Event { public: Event( double t, int eid, int hid ); ~Event(); void add( EventPQ& q ); void remove(); bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } bool operator > ( const Event & rhs ) const { return ( time > rhs.time ); } double time; int eventID; int hostID; EventPQ* mq; EventPQ::iterator mIt; }; // Event.cpp Event::Event( double t, int eid, int hid ) { time = t; eventID = eid; hostID = hid; } Event::~Event() {} void Event::add( EventPQ& q ) { mq = &q; mIt = q.insert( boost::shared_ptr<Event>(this) ); } void Event::remove() { mq.erase( mIt ); mq = 0; mIt = EventPQ::iterator(); } I was hoping that by making EventPQ a container of pointers, I could avoid wasting time copying Events into the container and avoid accidentally editing the wrong copy. Would it be dramatically easier to store the Events themselves in EventPQ instead? Does it make more sense to remove the time keys from Event objects and use them instead as keys in a multimap? Assuming the current implementation seems okay, my questions are: Do I need to specify how to sort on the pointers, rather than the objects, or does the multiset automatically know to sort on the objects pointed to? If I have a shared_ptr ptr1 to an Event that also has a pointer in the EventPQ container, how do I find and delete the corresponding pointer in EventPQ? Is it enough to .find( ptr1 ), or do I instead have to find by the key (time)? Is the Event::remove() sufficient for removing the pointer in the EventPQ container? There's a small chance multiple events could be created with the same time (obviously implied in the use of multiset). If the find() works on event times, to avoid accidentally deleting the wrong event, I was planning to throw in a further check on eventID and hostID. Does this seem reasonable? (Dumb syntax question) In Event.h, is the declaration of dummy class Event;, then the EventPQ typedef, and then the real class Event declaration appropriate? I'm obviously an inexperienced programmer with very spotty background--this isn't for homework. Would love suggestions and explanations. Please let me know if any part of this is confusing. Thanks.

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  • Unreachable code detected in case statement

    - by alex
    I have a code: protected override bool ProcessCmdKey(ref Message msg, Keys keyData) { switch (keyData) { case Keys.Alt|Keys.D1: if (this._condition1) { return true; } else { return base.ProcessCmdKey(ref msg, keyData); } break; case Keys.Control |Keys.U: if (this._condition2) { return true; } else { return base.ProcessCmdKey(ref msg, keyData); } break; default: return base.ProcessCmdKey(ref msg, keyData); } return true; It gives me "unreachable code detected" warning on breaks. Is it good practice not to use break operator here ? I don't want to turn off "unreachable code detected" warning. PS: There are many case in my ProcessCmdKey method.

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  • C++ Segementation fault in binary_function

    - by noryb009
    I'm using Visual Studio 2010 Beta 2 (also tried with NetBeans), and I'm having a segmentation fault in the following code: // One of the @link s20_3_3_comparisons comparison functors@endlink. template <class _Tp> struct less : public binary_function<_Tp, _Tp, bool> { bool operator()(const _Tp& __x, const _Tp& __y) const { return __x < __y; } //this is the problem line }; I don't know what in my program calls it, but I am trying to find out. (I think it's a map) Does anyone know what to do, or has encountered this before?

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  • How to display Preferences in a View

    - by Sybiam
    I'm building some sort of wizard to create user accounts in Sync and Manage account. I use a ViewFlipper my activity has to be an AccountAuthenticatorActivity. That said it also means I can't inherit PreferenceActivity. So I looked up in the code of PreferenceActivity and I believe it should be possible to have a PreferenceView that inherit from ListView. The Activity part of PreferenceActivity isn't really needed as far as I know. Though the PreferenceManager is what really blocks me. private PreferenceManager onCreatePreferenceManager() { PreferenceManager preferenceManager = new PreferenceManager(this, FIRST_REQUEST_CODE); preferenceManager.setOnPreferenceTreeClickListener(this); return preferenceManager; } This function imply that we can instatiate PreferenceManager using the operator new. Apparently, the sdk hide the constructor of the PreferenceManager. I'm kind of confused. Is there a way to inflate my preferences and display them without PreferenceActivity?

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  • Import CSV to class structure as the user defines

    - by Assimilater
    I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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