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  • SQL statement HAVING MAX(some+thing)=some+thing

    - by Andreas
    I'm having trouble with Microsoft Access 2003, it's complaining about this statement: select cardnr from change where year(date)<2009 group by cardnr having max(time+date) = (time+date) and cardto='VIP' What I want to do is, for every distinct cardnr in the table change, to find the row with the latest (time+date) that is before year 2009, and then just select the rows with cardto='VIP'. This validator says it's OK, Access says it's not OK. This is the message I get: "you tried to execute a query that does not include the specified expression 'max(time+date)=time+date and cardto='VIP' and cardnr=' as part of an aggregate function." Could someone please explain what I'm doing wrong and the right way to do it? Thanks

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  • Indexing datetime in MySQL

    - by User1
    What is the best way to index a datetime in MySQL? Which method is faster: Store the datetime as a double (via unix timestamp) Store the datetime as a datetime The application generating the timestamp data can output either format. Unfortunately, datetime will be a key for this particular data structure so speed will matter. Also, is it possible to make an index on an expression? For example, index on UNIX_TIMESTAMP(mydate) where mydate is a field in a table and UNIX_TIMESTAMP is a mysql function. I know that Postgres can do it. I'm thinking there must be a way in mysql as well.

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  • syntax to express mathematical formula concisely in your language of choice

    - by aaa
    hello. I am developing functional domain specific embedded language within C++ to translate formulas into working code as concisely and accurately as possible. Right now my language looks something like this: // implies two nested loops j=0:N, i=0,j (range(i) < j < N)[T(i,j) = (T(i,j) - T(j,i))/e(i+j)]; // implies summation over above expression sum(range(i) < j < N))[(T(i,j) - T(j,i))/e(i+j)]; I am looking for possible syntax improvements/extensions or just different ideas about expressing mathematical formulas as clearly and precisely as possible. Can you give me some syntax examples relating to my question which can be accomplished in your language of choice which consider useful. In particular, if you have some ideas about how to translate the above code segments, I would be happy to hear them Thank you

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  • Anonymous functions in C#

    - by Maxim Gershkovich
    The following syntax is valid VB.NET code Dim myCollection As New List(Of Stock) myCollection.Add(New Stock(Guid.NewGuid, "Item1")) myCollection.Add(New Stock(Guid.NewGuid, "Item2")) Dim res As List(Of Stock) = myCollection.FindAll(Function(stock As Stock) As Boolean If stock.Description = "Item2" Then Return True End If Return False End Function) How can I accomplish the same thing in C#? I have tried... myCollection.FindAll(bool delegate(Stock stock) { if (blah blah) { } }); But it appears I have somehow structured it incorrectly as I get the following error. "Error 1 Invalid expression term 'bool'"

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  • UPDATE from SELECT complains about more that one value returned

    - by Álvaro G. Vicario
    I have this data structure: request ======= building_id lot_code building ======== building_id lot_id lot === lot_id lot_code The request table is missing the value for the building_id column and I want to fill it in from the other tables. So I've tried this: UPDATE request SET building_id = ( SELECT bu.building_id FROM building bu INNER JOIN lot lo ON bu.lot_id=lo.lot_id WHERE lo.lot_code = request.lot_code ); But I'm getting this error: Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , , = or when the subquery is used as an expression. Is it due to wrong syntax? The data model allows more than one building per lot but actual data doesn't contain such cases so there should be at most one building_id per lot_code.

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  • trying to prune down a list of files

    - by romunov
    I have a list of files and I'm trying to extract all layer1_*.grd files. Is there a way of doing this in one grep expression? lof <- c("layer1_1.grd", "layer1_1.gri", "layer1_2.grd", "layer1_2.gri", "layer1_3.grd", "layer1_3.gri", "layer1_4.grd", "layer1_4.gri", "layer1_5.grd", "layer1_5.gri", "layer2_1.grd", "layer2_1.gri", "layer2_2.grd", "layer2_2.gri", "layer2_3.grd", "layer2_3.gri", "layer2_4.grd", "layer2_4.gri", "layer2_5.grd", "layer2_5.gri", "layer3_1.grd", "layer3_1.gri", "layer3_2.grd", "layer3_2.gri", "layer3_3.grd", "layer3_3.gri", "layer3_4.grd", "layer3_4.gri", "layer3_5.grd", "layer3_5.gri", "layer4_1.grd", "layer4_1.gri", "layer4_2.grd", "layer4_2.gri", "layer4_3.grd", "layer4_3.gri", "layer4_4.grd", "layer4_4.gri", "layer4_5.grd", "layer4_5.gri" I tried doing this in two steps: list.of.files <- list.files(pattern = c("1_")) list.of.files <- list.of.files[grep(".grd", list.of.files)] Can someone enlighten me how to do this with grep in one step? I naively tried passing list() and c() to the grep but, as you can imagine, it doesn't work. list.of.files <- list.files() list.of.files <- list.of.files[grep(list("1_", ".grd"), list.of.files)]

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  • jquery disable rule validation on a single field

    - by shake
    I am using mvc to create forms that are generated at runtime. For validation, I am trying my hand at the jquery validation library which is very convenient to use. I have the validation expression of each field in the cdata attribute of the tag <input type="text" name="xyz" id="xyz" class="defaultTextBox" cdata="{validate:{required:true, decimal:true, messages: {required:'Please enter an decimal value', decimal:'Please enter a valid decimal'}}}"> This works beautifully. Now one more requirement I have is that some fields are being shown and hidden according to the logic on the page and I need to disable the validation on the hidden fields such that they do not interfere with the form submission. Just toggling the required:true to false and back to true should be enough. Only i do not know how. Anyone has any experience with that?

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  • Does lookaround affect which languages can be matched by regular expressions?

    - by sepp2k
    There are some features in modern regex engines which allow you to match languages that couldn't be matched without that feature. For example the following regex using back references matches the language of all strings that consist of a word that repeats itself: (.+)\1. This language is not regular and can't be matched by a regex, which does not use back references. My question: Does lookaround also affect which languages can be matched by a regular expression? I.e. are there any languages that can be matched using lookaround, which couldn't be matched otherwise? If so, is this true for all flavors of lookaround (negative or positive lookahead or lookbehind) or just for some of them?

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  • "set -e" in shell and command substitution

    - by ivant
    In shell scripts set -e is often used to make them more robust by stopping the script when some of the commands executed from the script exits with non-zero exit code. It's usually easy to specify that you don't care about some of the commands succeeding by adding || true at the end. The problem appears when you actually care about the return value, but don't want the script to stop on non-zero return code, for example: output=$(possibly-failing-command) if [ 0 == $? -a -n "$output" ]; then ... else ... fi Here we want to both check the exit code (thus we can't use || true inside of command substitution expression) and get the output. However, if the command in command substitution fails, the whole script stops due to set -e. Is there a clean way to prevent the script from stopping here without unsetting -e and setting it back afterwards?

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  • Javascript .match plus jQuery keyup(), double match and strange behaviour

    - by Gremo
    Not really good in regular expression, but why when a match is found console.log fires two times? $('#name').keyup(function() { var regex = /[\€]/g; var count = (m = $(this).val().match(regex)) ? m.length : 0; // Num matches console.log(count); }); Output with 'hello': 0 0 0 0 0 After adding '€' symbol to 'hello' we have: 0 0 0 0 0 1 1 After adding 'h' symbol to 'hello€' we have: 0 0 0 0 0 1 1 1 Shouldn't be just one 1 after adding '€' to 'hello'?

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  • How to make RegexKitLite w/ iPhone SDK produce a list of all matches +/- and also return surrounding

    - by Matt
    I'd like to create a regular expression that will match and return based on the following criteria: 1) I have N search terms entered by a user 2) I have a body of text. 3) I want to return a list of all the occurrences of all the search terms entered by the user plus surrounding context. I think (\w+\W+){,4}(", ")(\W+\w+){,4} might work. 4) I don't know how to use RegexKitLite at all. Do I invoke a RegexKitLite class? or does it interface into NSString somehow?

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  • Generating dynamic C# based on textual data into the runtime?

    - by WeNeedAnswers
    Is there a quick and easy way to load textual C# into a program. I would like to load the LINQ from the database as an Expression and run it against some data (SQL or Array/List don't mind). I know I can do it using the C# CodeDom/ExpressionTree builder with Assembly Loading and Creating AppDomains, but this seems very long winded. Is there an easier way. I thought with the advent of .net 3.5 that the ExpressionTree would come to my aid, but I now realise that I have to write a parser to use this. Maybe there is a new trick in 4.0? Something along the lines of a dynamic languages Parse would be great. Any suggestions greatly appreciated.

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  • Pass property to access using .NET

    - by BitFiddler
    I'm fairly sure this is possible, but what I want to do is have a generic method where I can pass in an object along with a Expression that will tell the method which Property to use in it's logic. Can anyone get me started on the syntax for something like this? Essentially what I would like to code is something like: Dim firstNameMapper as IColumnMapper = new ColumnMapper(of Author)(Function(x) x.FirstName) Dim someAuthorObject as new Author() fistNameMapper.Map("Richard", someAuthorObject) Now the mapper object would know to set the FirstName property to "Richard". Now using a Function here won't work, I know this... I'm just trying to give an idea what I'm trying to work towards. Thanks for any help!

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  • C# ToDictionary can valueSelector give null?

    - by Trimack
    Hi, I want to make a dictionary out of list in a way, that the list becomes keys and values would be empty. I have following code Dictionary<XmlTest, int?> testBattery = new XmlTests().GetRandomTestBattery(id). ToDictionary(k => k, v => null); But I am getting the error "Cannot convert lambda expression to type System.Collections.Generic.IEqualityComparer' because it is not a delegate type" Any ideas how could I fix it? (I know I could iterate through and fill the dict one element at a time, but I simply want to use something more elegant)

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  • PHP Regex Question

    - by oyerli
    Hi, I am developing an application using PHP but I am new to regular expressions, I could not find a solution to my problem. I want to replace all occurences of #word with a link, i have written a preg_match for this: $text=preg_replace('~#([\p{L}|\p{N}]+)~u', '<a href="/?aranan=$1">#$1</a>', $text); The problem is, this regular expression also matches the html character codes like &#039; and gives corrupt output. I need to exclude the words starting with &# but i do not know how to do that using regular expressions. Thanks for your help.

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  • Fluent NHibernate beginner problem: How to convert single column data to custom class?

    - by Stefan Ahlm
    I am very new to Fluent NHibernate and I have a problem that I cant find the answer to. I have a string column in my database table, containing a mathematical expression i.e: "10 + 15 * 5". On my entity I have a property that I call Formula and this returns a class that contains the mathematical "formula" (not as a string). I beleive this post http://intellect.dk/post/Implementing-custom-types-in-nHibernate.aspx explains how to solve it for NHibernate. But I am not sure... How do I get this working with Fluent NHibernate?

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  • Django: query spanning multiple many-to-many relationships

    - by Brant
    I've got some models set up like this: class AppGroup(models.Model): users = models.ManyToManyField(User) class Notification(models.Model): groups_to_notify = models.ManyToManyField(AppGroup) The User objects come from django's authentication system. Now, I am trying to get all the notifications pertaining to the groups that the current user is a part of. I have tried.. notifications = Notification.objects.filter(groups_to_notify=AppGroup.objects.filter(users=request.user)) But that gives an error: more than one row returned by a subquery used as an expression Which I suppose is because the groups_to_notify is checking against several groups. How can I grab all the notifications meant for the user based on the groups he is a part of?

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  • NHibernate: discriminator without common base class?

    - by joniba
    Is it possible to map two classes to the same property without them sharing a common base class? For example, a situation like this: class Rule { public virtual int SequenceNumber { get; set; } public virtual ICondition Condition { get; set; } } interface ICondition { } class ExpressionCondition : ICondition { public virtual string Expression { get; set; } } class ThresholdCondition : ICondition { public virtual int Threshold { get; set; } } I also cannot add some empty abstract class that both conditions inherit from because the two ICondition implementations exist in different domains that are not allowed to reference each other. (Please no responses telling me that this situation should not occur in the first place - I'm aware of it and it doesn't help me.)

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  • How do I wrap this BAIL macro in Xcode?

    - by willc2
    I use this little snippet to halt my iPhone app in the simulator. NSAssert((0), @"Bail early while testing"); When I try to make it a #defined macro like this: #define BAILNOW (NSAssert((0), @"Bail early while testing")) I get this build error: error: expected expression before 'do' It seems to be related to the nesting of the NSAssert() macro but I'm at a loss as to how to get around it. Should I dig into the NSAssertionHandler docs or is there some simpler way to halt the app in it's tracks? Or should I just set a breakpoint and get on with my life?

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  • simple putStrLn in Haskell/Yampa with arrows syntax

    - by sisif
    i'm using Haskell with the Yampa FRP library which uses the arrows language extension. how can i do a simple putStrLn in a SF? mySF = proc x -> do y <- identity -< x*x putStrLn "Hello World!" ++ show y returnA -< y the arrow syntax complains about the expression not bein an arrow (of course), but even with arrows i get no output output <- identity -< putStrLn "Hello World!"

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  • Why size_t arguments in template declaration need to be const?

    - by ArunSaha
    I can have std::bitset< 10 > bitsetA; or const size_t LengthB = 20; std::bitset< LengthB > bitsetB; without any problem. But, if the length is not const size_t LengthC = 30; std::bitset< LengthC > bitsetC; // Line 30, say I face the following compilation error 'LengthC' cannot appear in a constant-expression template argument 1 is invalid What is the reason for that? What would be the problem, for compiler and for user code, if line 30 was to be accepted? Is it because LengthC might have some alias?

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  • How to deal with the new line character in the Silverlight TextBox

    - by Ian Oakes
    When using a multi-line TextBox (AcceptsReturn="True") in Silverlight, line feeds are recorded as \r rather than \r\n. This is causing problems when the data is persisted and later exported to another format to be read by a Windows application. I was thinking of using a regular expression to replace any single \r characters with a \r\n, but I suck at regex's and couldn't get it to work. Because there may be a mixture of line endings just blindy replacing all \r with \r\n doesn't cut it. So two questions really... If regex is the way to go what's the correct pattern? Is there a way to get Silverlight to respect it's own Environment.NewLine character in TextBox's and have it insert \r\n rather just a single \r?

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  • ASP.Net mysterious behaviour

    - by kalan
    Does anyone have any idea why this works (expression in the if-clause) if (!(childNode.Roles != null && !Helper.HasEqualElements((string[])childNode.Roles, System.Web.Security.Roles.GetRolesForUser()))) AddNode(childNode, parentNode); And this doesn't if (childNode.Roles == null || Helper.HasEqualElements((string[])childNode.Roles, System.Web.Security.Roles.GetRolesForUser())) AddNode(childNode, parentNode); The problem is that the second if-clause sometimes doesn't work. Though it always works in debug mode, but it sometimes fails while running. And the strange thing is that these two pieces of code seems absolutely equal for me.

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  • my window's handle is unused and cannot be evaluated

    - by numerical25
    I am trying to encapsulate my Win32 application into a class. My problem occurs when trying to initiate my primary window for the application below is my declaration and implementation... I notice the issue within my class method InitInstance(); declaration #pragma once #include "stdafx.h" #include "resource.h" #define MAX_LOADSTRING 100 class RenderEngine { protected: int m_width; int m_height; ATOM RegisterEngineClass(); public: static HINSTANCE m_hInst; HWND m_hWnd; int m_nCmdShow; TCHAR m_szTitle[MAX_LOADSTRING]; // The title bar text TCHAR m_szWindowClass[MAX_LOADSTRING]; // the main window class name bool InitWindow(); bool InitDirectX(); bool InitInstance(); //static functions static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam); static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam); int Run(); }; implementation #include "stdafx.h" #include "RenderEngine.h" HINSTANCE RenderEngine::m_hInst = NULL; bool RenderEngine::InitWindow() { RenderEngine::m_hInst = NULL; // Initialize global strings LoadString(m_hInst, IDS_APP_TITLE, m_szTitle, MAX_LOADSTRING); LoadString(m_hInst, IDC_RENDERENGINE, m_szWindowClass, MAX_LOADSTRING); if(!RegisterEngineClass()) { return false; } if(!InitInstance()) { return false; } return true; } ATOM RenderEngine::RegisterEngineClass() { WNDCLASSEX wcex; wcex.cbSize = sizeof(WNDCLASSEX); wcex.style = CS_HREDRAW | CS_VREDRAW; wcex.lpfnWndProc = RenderEngine::WndProc; wcex.cbClsExtra = 0; wcex.cbWndExtra = 0; wcex.hInstance = m_hInst; wcex.hIcon = LoadIcon(m_hInst, MAKEINTRESOURCE(IDI_RENDERENGINE)); wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); wcex.lpszMenuName = MAKEINTRESOURCE(IDC_RENDERENGINE); wcex.lpszClassName = m_szWindowClass; wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL)); return RegisterClassEx(&wcex); } LRESULT CALLBACK RenderEngine::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent; PAINTSTRUCT ps; HDC hdc; switch (message) { case WM_COMMAND: wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(m_hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_PAINT: hdc = BeginPaint(hWnd, &ps); // TODO: Add any drawing code here... EndPaint(hWnd, &ps); break; case WM_DESTROY: PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0; } bool RenderEngine::InitInstance() { m_hWnd = NULL;// When I step into my code it says on this line 0x000000 unused = ??? expression cannot be evaluated m_hWnd = CreateWindow(m_szWindowClass, m_szTitle, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, m_hInst, NULL); if (!m_hWnd)// At this point, memory has been allocated unused = ??. It steps over this { return FALSE; } if(!ShowWindow(m_hWnd, m_nCmdShow))// m_nCmdShow = 1 and m_hWnd is still unused and expression {//Still cannot be evaluated. This statement is true. and shuts down. return false; } UpdateWindow(m_hWnd); return true; } // Message handler for about box. INT_PTR CALLBACK RenderEngine::About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE; } int RenderEngine::Run() { MSG msg; HACCEL hAccelTable; hAccelTable = LoadAccelerators(m_hInst, MAKEINTRESOURCE(IDC_RENDERENGINE)); // Main message loop: while (GetMessage(&msg, NULL, 0, 0)) { if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) { TranslateMessage(&msg); DispatchMessage(&msg); } } return (int) msg.wParam; } and my winMain function that calls the class // RenderEngine.cpp : Defines the entry point for the application. #include "stdafx.h" #include "RenderEngine.h" // Global Variables: RenderEngine go; int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { UNREFERENCED_PARAMETER(hPrevInstance); UNREFERENCED_PARAMETER(lpCmdLine); // TODO: Place code here. RenderEngine::m_hInst = hInstance; go.m_nCmdShow = nCmdShow; if(!go.InitWindow()) { return 0; } go.Run(); return 0; }

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  • Would it be simply better to use the system's functions rather than use the language?

    - by Nullw0rm
    There are many scenarios where I've questioned PHP's performance with some of its functions, and whether I should build a complex class to handle specific things using its seemingly slow tools. For example, Complex regular expressions with sed and processing with awk would seemingly be exponential in performance rather than making PHP's regular expression and seemingly excessive functions parse and in time manage to finish it. If I were to do a lot of network tasks such as MX lookups/DIGging/retrieving simultaneously I would rather pass it via system() and let the OS handle it itself. There are simply too many functions in PHP, that are inefficient and result in slow pages or can be handled easier by the OS. What are your opinions? Do you think I should do the hard work with the OS in its own/custom functions?

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