Search Results

Search found 9996 results on 400 pages for 'delete relation'.

Page 163/400 | < Previous Page | 159 160 161 162 163 164 165 166 167 168 169 170  | Next Page >

  • Freeing ImageData when deleting a Canvas

    - by user578770
    I'm writing a XUL application using HTML Canvas to display Bitmap images. I'm generating ImageDatas and imporingt them in a canvas using the putImageData function : for(var pageIndex=0;pageIndex<100;pageIndex++){ this.img = imageDatas[pageIndex]; /* Create the Canvas element */ var imgCanvasTmp = document.createElementNS("http://www.w3.org/1999/xhtml",'html:canvas'); imgCanvasTmp.setAttribute('width', this.img.width); imgCanvasTmp.setAttribute('height', this.img.height); /* Import the image into the Canvas */ imgCanvasTmp.getContext('2d').putImageData(this.img, 0, 0); /* Use the Canvas into another part of the program (Commented out for testing) */ // this.displayCanvas(imgCanvasTmp,pageIndex); } The images are well imported but there seems to be a memory leak due to the putImageData function. When exiting the "for" loop, I would expect the memory allocated for the Canvas to be freed but, by executing the code without executing putImageData, I noticed that my program at the end use 100Mb less (my images are quite big). I came to the conclusion that the putImageData function prevent the garbage collector to free the allocated memory. Do you have any idea how I could force the garbage collector to free the memory? Is there any way to empty the Canvas? I already tried to delete the canvas using the delete operator or to use the clearRect function but it did nothing. I also tried to reuse the same canvas to display the image at each iteration but the amount of memory used did not changed, as if the image where imported without deleting the existing ones...

    Read the article

  • List all foreign key constraints that refer to a particular column in a specific table

    - by Sid
    I would like to see a list of all the tables and columns that refer (either directly or indirectly) a specific column in the 'main' table via a foreign key constraint that has the ON DELETE=CASCADE setting missing. The tricky part is that there would be an indirect relationships buried across up to 5 levels deep. (example: ... great-grandchild- FK3 = grandchild = FK2 = child = FK1 = main table). We need to dig up the leaf tables-columns, not just the very 1st level. The 'good' part about this is that execution speed isn't of concern, it'll be run on a backup copy of the production db to fix any relational issues for the future. I did SELECT * FROM sys.foreign_keys but that gives me the name of the constraint - not the names of the child-parent tables and the columns in the relationship (the juicy bits). Plus the previous designer used short, non-descriptive/random names for the FK constraints, unlike our practice below The way we're adding constraints into SQL Server: ALTER TABLE [dbo].[UserEmailPrefs] WITH CHECK ADD CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] FOREIGN KEY([UserId]) REFERENCES [dbo].[UserMasterTable] ([UserId]) ON DELETE CASCADE GO ALTER TABLE [dbo].[UserEmailPrefs] CHECK CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] GO The comments in this SO question inpire this question.

    Read the article

  • Identifying memory leaks in C++

    - by Dororo
    I've got the following bit of code, which I've narrowed down to be causing a memory leak (that is, in Task Manager, the Private Working Set of memory increases with the same repeated input string). I understand the concepts of heaps and stacks for memory, as well as the general rules for avoiding memory leaks, but something somewhere is still going wrong: while(!quit){ char* thebuffer = new char[210]; //checked the function, it isn't creating the leak int size = FuncToObtainInputTextFromApp(thebuffer); //stored in thebuffer string bufferstring = thebuffer; int startlog = bufferstring.find("$"); int endlog = bufferstring.find("&"); string str_text=""; str_text = bufferstring.substr(startlog,endlog-startlog+1); String^ str_text_m = gcnew String(str_text_m.c_str()); //some work done delete str_text_m; delete [] thebuffer; } The only thing I can think of is it might be the creation of 'string str_text' since it never goes out of scope since it just reloops in the while? If so, how would I resolve that? Defining it outside the while loop wouldn't solve it since it'd also remain in scope then too. Any help would be greatly appreciated.

    Read the article

  • Best approach to cache Counts from SQL tables ?

    - by pixel3cs
    I would like to develop a Forum from scratch, with special needs and customization. I would like to prepare my forum for intensive usage and wondering how to cache things like User posts count and User replies count. Having only three tables, tblForum, tblForumTopics, tblForumReplies, what is the best approach of cache the User topics and replies counts ? Think at a simple scenario: user press a link and open the Replies.aspx?id=x&page=y page, and start reading replies. On the HTTP Request, the server will run an SQL command wich will fetch all replies for that page, also "inner joining with tblForumReplies to find out the number of User replies for each user that replied." select tblForumReplies.*, tblFR.TotalReplies from tblForumReplies inner join ( select IdRepliedBy, count(*) as TotalReplies from tblForumReplies group by IdRepliedBy ) as tblFR on tblFR.IdRepliedBy = tblForumReplies.IdRepliedBy Unfortunately this approach is very cpu intensive, and I would like to see your ideas of how to cache things like table Counts. If counting replies for each user on insert/delete, and store it in a separate field, how to syncronize with manual data changing. Suppose I will manually delete Replies from SQL.

    Read the article

  • help with basic MVC project

    - by Shrewd Demon
    hi, i am creating a demo MVC project and i am getting a Null Object Reference error for the following code. <% foreach (var item in Model) { %> <tr> <td> <%= Html.ActionLink("Edit", "Edit", new { /* id=item.PrimaryKey */ }) %> | <%= Html.ActionLink("Details", "Details", new { /* id=item.PrimaryKey */ })%> | <%= Html.ActionLink("Delete", "Delete", new { /* id=item.PrimaryKey */ })%> </td> <td> <%= Html.Encode(item.ContactEmail) %> </td> <td> <%= Html.Encode(item.YourQuery) %> </td> </tr> <% } %> i get an error in the first line itself (var item in Model) coz i am getting the Model object as null. Can anyone please help me. thanks.

    Read the article

  • remove row on click on specific td of that row by jquery

    - by I Like PHP
    i have an table <table class="oldService"> <thead> <th>name</th> <th>age</th> <th>action</th> </thead> <tbody> <?php foreach($array as $k=>$v){ ?> <tr> <td><?php echo $k[name] ?></td> <td><?php echo $k[age]?></td> <td id="<?php $k[id]" class="delme">X</td> </tr> <?php } ?> </tbody> <table> now i want to delete any row by clicking on X of each row except first and last row, and also need to confirm before deletion. i used below jquery <script type="text/javascript"> jQuery(document).ready(function(){ jQuery('table.oldService>tbody tr').not(':first').not(':last').click(function(){ if(confirm('want to delete!')){ jQuery(jQuery(this).addClass('del').fadeTo(400, 0, function() { jQuery(this).remove()})); jQuery.get('deleteService.php', {id:jQuery(this).attr('id')}); } else return false;}); }); </script> this is working perfect,but it execute by click on that row( means any td), i want that this event only occour when user click on X(third td) . please suggest me how to modify this jquery so that the event occur on click of X.

    Read the article

  • Passing values for method

    - by Kasun
    I beginner for programming. So can you please show me how to pass values for your compile() method. class CL { private const string clexe = @"cl.exe"; private const string exe = "Test.exe", file = "test.cpp"; private string args; public CL(String[] args) { this.args = String.Join(" ", args); this.args += (args.Length > 0 ? " " : "") + "/Fe" + exe + " " + file; } public Boolean Compile(String content, ref string errors) { //remove any old copies if (File.Exists(exe)) File.Delete(exe); if (File.Exists(file)) File.Delete(file); File.WriteAllText(file, content); Process proc = new Process(); proc.StartInfo.UseShellExecute = false; proc.StartInfo.RedirectStandardOutput = true; proc.StartInfo.RedirectStandardError = true; proc.StartInfo.FileName = clexe; proc.StartInfo.Arguments = this.args; proc.StartInfo.CreateNoWindow = true; proc.Start(); //errors += proc.StandardError.ReadToEnd(); errors += proc.StandardOutput.ReadToEnd(); proc.WaitForExit(); bool success = File.Exists(exe); return success; } }

    Read the article

  • Copy object using pointer (templates)

    - by Azodious
    How the push_back of stl::vector is implemented so it can make copy of any datatype .. may be pointer, double pointer and so on ... I'm implementing a template class having a function push_back almost similar to vector. Within this method a copy of argument should be inserted in internal memory allocated memory. but the argument is a pointer. (an object pointer). Can you pls tell how to create copy from pointer. so that if i delete the pointer in caller still the copy exists in my template class? Code base is as follows: template<typename T> class Vector { public: void push_back(const T& val_in) { T* a = *(new T(val_in)); m_pData[SIZE++] = a; } } Caller: Vector<MyClass*> v(3); MyClass* a = new MyClass(); a->a = 0; a->b = .5; v.push_back(a); delete a; Thanks.

    Read the article

  • Generic Func<> as parameter to base method

    - by WestDiscGolf
    I might be losing the plot, but I hope someone can point me in the right direction. What am I trying to do? I'm trying to write some base methods which take Func< and Action so that these methods handle all of the exception handling etc. so its not repeated all over the place but allow the derived classes to specify what actions it wants to execute. So far this is the base class. public abstract class ServiceBase<T> { protected T Settings { get; set; } protected ServiceBase(T setting) { Settings = setting; } public void ExecAction(Action action) { try { action(); } catch (Exception exception) { throw new Exception(exception.Message); } } public TResult ExecFunc<T1, T2, T3, TResult>(Func<T1, T2, T3, TResult> function) { try { /* what goes here?! */ } catch (Exception exception) { throw new Exception(exception.Message); } } } I want to execute an Action in the following way in the derived class (this seems to work): public void Delete(string application, string key) { ExecAction(() => Settings.Delete(application, key)); } And I want to execute a Func in a similar way in the derived class but for the life of me I can't seem to workout what to put in the base class. I want to be able to call it in the following way (if possible): public object Get(string application, string key, int? expiration) { return ExecFunc(() => Settings.Get(application, key, expiration)); } Am I thinking too crazy or is this possible? Thanks in advance for all the help.

    Read the article

  • Locking a GDI+ Bitmap in Native C++?

    - by user146780
    I can find many examples on how to do this in managed c++ but none for unmanaged. I want to get all the pixel data as efficiently as possible, but some of the scan0 stuff I would need more info about so I can properly iterate through the pixel data and get each rgba value from it. right now I have this: Bitmap *b = new Bitmap(filename); if(b == NULL) { return 0; } UINT w,h; w = b->GetWidth(); h = b->GetHeight(); Rect *r = new Rect(0,0,w,h); BitmapData *lockdat; b->LockBits(r,ImageLockModeRead,PixelFormatDontCare,lockdat); delete(r); if(w == 0 && h == 0) { return 0; } Color c; std::vector<GLubyte> pdata(w * h * 4,0.0); for (unsigned int i = 0; i < h; i++) { for (unsigned int j = 0; j < w; j++) { b->GetPixel(j,i,&c); pdata[i * 4 * w + j * 4 + 0] = (GLubyte) c.GetR(); pdata[i * 4 * w + j * 4 + 1] = (GLubyte) c.GetG(); pdata[i * 4 * w + j * 4 + 2] = (GLubyte) c.GetB(); pdata[i * 4 * w + j * 4 + 3] = (GLubyte) c.GetA(); } } delete(b); return CreateTexture(pdata,w,h); How do I use lockdat to do the equivalent of getpixel? Thanks

    Read the article

  • Combine Arbitrary number of polygons together

    - by Jakobud
    I have an arbitrary number of polygons (hexes in this case) that are arranged randomly, but they are all touching another hex. Each individual hex has 6 x,y vertices. The vertex's are known for all the hexes. Can anyone point me in the direction of an algorithm that will combine all the hexes into a single polygon? Essentially I'm just looking for a function that spits out an array of vertex locations that are ordered in a way that when drawing lines from one to the next, it forms the polygon. This is my method so far: Create array of all the vertices for all the hexes. Determine the number of times a vertex occurs in the array If vertex is in the array 3+ times, delete the vertices from the array. If vertex is in the array 2 times, delete one of them. The next step is tricky though. I'm using canvas to draw out these polygons, which essentially involves drawing a line from one vertex to the next. So the order of the vertices in the final array is important. It can't be sorted arbitrarily. Also, I'm not looking for a "convex hull" algorithm, as that would not draw the polygon correctly. Are there any functions out there that do something like this? Am I on the right track or is there a better more efficient way?

    Read the article

  • JavaScript array random index insertion and deletion

    - by Tomi
    I'm inserting some items into array with randomly created indexes, for example like this: var myArray = new Array(); myArray[123] = "foo"; myArray[456] = "bar"; myArray[789] = "baz"; ... In other words array indexes do not start with zero and there will be "numeric gaps" between them. My questions are: Will these numeric gaps be somehow allocated (and therefore take some memory) even when they do not have assigned values? When I delete myArray[456] from upper example, would items below this item be relocated? EDIT: Regarding my question/concern about relocation of items after insertion/deletion - I want to know what happens with the memory and not indexes. More information from wikipedia article: Linked lists have several advantages over dynamic arrays. Insertion of an element at a specific point of a list is a constant-time operation, whereas insertion in a dynamic array at random locations will require moving half of the elements on average, and all the elements in the worst case. While one can "delete" an element from an array in constant time by somehow marking its slot as "vacant", this causes fragmentation that impedes the performance of iteration.

    Read the article

  • What does the destructor do silently?

    - by zhanwu
    Considering the following code which looks like that the destructor doesn't do any real job, valgrind showed me clearly that it has memory leak without using the destructor. Any body can explain me what does the destructor do in this case? #include <iostream> using namespace std; class A { private: int value; A* follower; public: A(int); ~A(); void insert(int); }; A::A(int n) { value = n; follower = NULL; } A::~A() { if (follower != NULL) delete follower; cout << "do nothing!" << endl; } void A::insert(int n) { if (this->follower == NULL) { A* f = new A(n); this->follower = f; } else this->follower->insert(n); } int main(int argc, char* argv[]) { A* objectA = new A(1); int i; for (i = 0; i < 10; i++) objectA->insert(i); delete objectA; }

    Read the article

  • got undefined variable in php code

    - by Newbie New
    I got a error message when I run my php however the result is come out this is my code function cart() { foreach($_SESSION as $name => $value) { if ($value>0) { if (substr($name, 0, 5) == 'cart_'){ $id = substr($name, 5, (strlen($name)-5)); $get = mysql_query('SELECT id, name, price FROM products WHERE id=' .mysql_real_escape_string((int)$id)); while ($get_row = mysql_fetch_assoc($get)){ $sub = $get_row['price'] * $value; echo $get_row['name'].' x '.$value.' @ &pound'.number_format($get_row['price'], 2).' = &pound'.number_format($sub, 2).' <a href="cart.php?remove='.$id.'">[-]</a> <a href="cart.php?add='.$id.'">[+]</a> <a href="cart.php?delete='.$id.'">[Delete]</a><br />' ; } } $total += $sub; } } echo $total; } ?> I got a error message Notice: Undefined variable: total in C:\xampp\htdocs\shoppingcart\cart.php on line 54 which line 54 is echo $total; what's wrong with my code?? I think I have defined the code in $total += $sub; thanks for helping me :)

    Read the article

  • Boost shared_ptr use_count function

    - by photo_tom
    My application problem is the following - I have a large structure foo. Because these are large and for memory management reasons, we do not wish to delete them when processing on the data is complete. We are storing them in std::vector<boost::shared_ptr<foo>>. My question is related to knowing when all processing is complete. First decision is that we do not want any of the other application code to mark a complete flag in the structure because there are multiple execution paths in the program and we cannot predict which one is the last. So in our implementation, once processing is complete, we delete all copies of boost::shared_ptr<foo>> except for the one in the vector. This will drop the reference counter in the shared_ptr to 1. Is it practical to use shared_ptr.use_count() to see if it is equal to 1 to know when all other parts of my app are done with the data. One additional reason I'm asking the question is that the boost documentation on the shared pointer shared_ptr recommends not using "use_count" for production code.

    Read the article

  • GTK+: How do I process RadioMenuItem choice without marking it chosen? And vise versa

    - by eugene.shatsky
    In my program, I've got a menu with a group of RadioMenuItem entries. Choosing one of them should trigger a function which can either succeed or fail. If it fails, this RadioMenuItem shouldn't be marked chosen (the previous one should persist). Besides, sometimes I want to set marked item without running the choice processing function. Here is my current code: # Update seat menu list def update_seat_menu(self, seats, selected_seat=None): seat_menu = self.builder.get_object('seat_menu') # Delete seat menu items for menu_item in seat_menu: # TODO: is it a good way? does remove() delete obsolete menu_item from memory? if menu_item.__class__.__name__ == 'RadioMenuItem': seat_menu.remove(menu_item) # Fill menu with new items group = [] for seat in seats: menu_item = Gtk.RadioMenuItem.new_with_label(group, str(seat[0])) group = menu_item.get_group() seat_menu.append(menu_item) if str(seat[0]) == selected_seat: menu_item.activate() menu_item.connect("activate", self.choose_seat, str(seat[0])) menu_item.show() # Process item choice def choose_seat(self, entry, seat_name): # Looks like this is called when item is deselected, too; must check if active if entry.get_active(): # This can either succeed or fail self.logind.AttachDevice(seat_name, '/sys'+self.device_syspath, True) Chosen RadioMenuItem gets marked irrespective of the choose_seat() execution result; and the only way to set marked item without triggering choose_seat() is to re-run update_seat_menu() with selected_seat argument, which is an overkill. I tried to connect choose_seat() with 'button-release-event' instead of 'activate' and call entry.activate() in choose_seat() if AttachDevice() succeeds, but this resulted in whole X desktop lockup until AttachDevice() timed out, and chosen item still got marked.

    Read the article

  • Can you explain this generics behavior and if I have a workaround?

    - by insta
    Sample program below: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericsTest { class Program { static void Main(string[] args) { IRetrievable<int, User> repo = new FakeRepository(); Console.WriteLine(repo.Retrieve(35)); } } class User { public int Id { get; set; } public string Name { get; set; } } class FakeRepository : BaseRepository<User>, ICreatable<User>, IDeletable<User>, IRetrievable<int, User> { // why do I have to implement this here, instead of letting the // TKey generics implementation in the baseclass handle it? //public User Retrieve(int input) //{ // throw new NotImplementedException(); //} } class BaseRepository<TPoco> where TPoco : class,new() { public virtual TPoco Create() { return new TPoco(); } public virtual bool Delete(TPoco item) { return true; } public virtual TPoco Retrieve<TKey>(TKey input) { return null; } } interface ICreatable<TPoco> { TPoco Create(); } interface IDeletable<TPoco> { bool Delete(TPoco item); } interface IRetrievable<TKey, TPoco> { TPoco Retrieve(TKey input); } } This sample program represents the interfaces my actual program uses, and demonstrates the problem I'm having (commented out in FakeRepository). I would like for this method call to be generically handled by the base class (which in my real example is able to handle 95% of the cases given to it), allowing for overrides in the child classes by specifying the type of TKey explicitly. It doesn't seem to matter what parameter constraints I use for the IRetrievable, I can never get the method call to fall through to the base class. Also, if anyone can see an alternate way to implement this kind of behavior and get the result I'm ultimately looking for, I would be very interested to see it. Thoughts?

    Read the article

  • What's the point of indicating AllowMultiple=false on an abstract Attribute class?

    - by tvanfosson
    On a recent question about MVC attributes, someone asked whether using HttpPost and HttpDelete attributes on an action method would result in either request type being allowed or no requests being allowed (since it can't be both a Post and a Delete at the same time). I noticed that ActionMethodSelectorAttribute, from which HttpPostAttribute and HttpDeleteAttribute both derive is decorated with [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)] I had expected it to not allow both HttpPost and HttpDelete on the same method because of this, but the compiler doesn't complain. My limited testing tells me that the attribute usage on the base class is simply ignored. AllowMultiple seemingly only disallows two of the same attribute from being applied to a method/class and doesn't seem to consider whether those attributes derive from the same class which is configured to not allow multiples. Moreover, the attribute usage on the base class doesn't even preclude your from changing the attribute usage on a derived class. That being the case, what's the point of even setting the values on the base attribute class? Is it just advisory or am I missing something fundamental in how they work? FYI - it turns out that using both basically precludes that method from ever being considered. The attributes are evaluated independently and one of them will always indicate that the method is not valid for the request since it can't simultaneously be both a Post and a Delete.

    Read the article

  • iPhone: How to run a Beta build, in addition to the App Store build?

    - by rondoagogo
    Hi, All! I have an app on the Store for which we’re readying an update. The other members of our team have the App Store version already loaded up (~purchased) on their respective iPhones -- and those contain User Data which each member needs to be able to keep. In the meantime, we need to test out a Beta version of the next version of the app. Presumably, we’d need to have the two versions (ad hoc, and app store) co-existing on each device, at least until everyone’s signed off on the beta, and it’s uploaded to the store (at which point, they'd delete the beta version). [Once it’s on the Store, of course, they can each update their main (i.e., Release) version of the app via the usual App Store 'update' mechanism -- and then delete the beta version from their devices. In that case, all their user data is still retained intact.] So assuming that’s the proper workflow ... How do I issue a Beta to the team, and have it not replace/overwrite the existing App Store version? I’ve tried customizing parameters in the beta’s “[appname]-Info.plist”, but haven’t found a setting yet that allows the two versions (beta and release) to co-exist on the same device. Any ideas? And is this this is the proper approach to them being able to keep their data? (And last, how might I do it with & without a script? I assume there's just one parameter that'd need to be changed.) I hope this all makes sense -- thank you in advance for your help!

    Read the article

  • codeigniter avoiding html div's

    - by rabidmachine9
    Hello there!Is there a proper syntax to avoid div's in codeigniter? I don't really like opening and closing tags all the time... <div class="theForm"> <?php echo form_open('edit/links');//this form uploads echo "Enter the Name: ". form_input('name','name'); echo "Enter the Link: ". form_input('url','url'); echo " ".form_submit('submit', 'Submit'); echo form_close(); if (isset($linksQuery) && count($linksQuery)){ foreach($linksQuery as $link){ echo anchor($link['link'], $link['name'].".", array("class" => "links")); echo form_open('edit/links',array('class' => 'deleteForm')); echo form_hidden('name',$link['name']); echo " ".form_submit('delete','Delete'); echo form_close(); echo br(2); } } ?> </div>

    Read the article

  • Strange lazy load problem

    - by JooLio
    public class QuickQuoteTemplate { ... public virtual IList<QuickQuoteTemplateItem> InnerItems { get; set; } ... } public class QuickQuoteTemplateItem { ... public virtual IList<QuickQuoteTemplateItem> InnerItems { get; set; } ... } <class name="QuickQuoteTemplate" table="SA_QUICK_QUOTE_TEMPLATE"> ... <bag name="InnerItems" lazy="false" inverse="true" cascade="delete" > <key column="PARENT_QQ_TEMPLATE_ID" ></key> <one-to-many class="QuickQuoteTemplateItem" /> </bag> ... </class> <class name="QuickQuoteTemplateItem" table="SA_QUICK_QUOTE_TEMPLATE_ITEMS"> ... <bag name="InnerItems" lazy="false" inverse="false" cascade="delete"> <key column="PARENT_ITEM_ID" /> <one-to-many class="QuickQuoteTemplateItem" /> </bag> ... </class> InnerItems collections is set as no lazy, but after disposing the ISession instance, quickQuote.InnerItems is crying "failed to lazily initialize a collection, no session or session was closed". I've even tried to call InnerItems before the session is closed by myself. It successfully retrieves, but after disposing of the session it becomes not initialized.

    Read the article

  • MySQL Multiple Table Join

    - by hitman001
    I have a 3 tables that I'm trying to join and get distinct results. CREATE TABLE `car` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB mysql> select * from car; +----+-------+ | id | name | +----+-------+ | 1 | acura | +----+-------+ CREATE TABLE `tires` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `tire_desc` varchar(255) DEFAULT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new_fk_constraint` (`car_id`), CONSTRAINT `new_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from tires; +----+-------------+--------+ | id | tire_desc | car_id | +----+-------------+--------+ | 1 | front_right | 1 | | 2 | front_left | 1 | +----+-------------+--------+ CREATE TABLE `lights` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `lights_desc` varchar(255) NOT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new1_fk_constraint` (`car_id`), CONSTRAINT `new1_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from lights; +----+-------------+--------+ | id | lights_desc | car_id | +----+-------------+--------+ | 1 | right_light | 1 | | 2 | left_light | 1 | +----+-------------+--------+ Here is my query. mysql> SELECT name, group_concat(tire_desc), group_concat(lights_desc) FROM car left join tires on car.id = tires.car_id left join lights on car.id = car_id group by car.id; +-------+-----------------------------------------------+-----------------------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+-----------------------------------------------+ | acura | front_right,front_right,front_left,front_left | right_light,left_light,right_light,left_light | +-------+-----------------------------------------------+-----------------------------------------------+ I get duplicate entires and this is what I would like to get. +-------+-----------------------------------------------+--------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+--------------------------------+ | acura | front_right,front_left | right_light,left_light | +-------+-----------------------------------------------+--------------------------------+ I cannot use distinct in group_concat because I might have legitimate duplicates which I would like to keep. Is there any way to do this query using joins and not using inner selects like the statement below? SELECT name, (select group_concat(tire_desc) from tires where car.id = tires.car_id), (select group_concat(lights_desc) from lights where car.id = lights.car_id) FROM car Also, if I will use inner selects, will there be any performance issues over joins?

    Read the article

  • Elegent methods for caching search results from RESTful service?

    - by Paul
    I have a RESTful web service which I access from the browser using JavaScript. As an example, say that this web service returns a list of all the Message resources assigned to me when I send a GET request to /messages/me. For performance reasons, I'd like to cache this response so that I don't have to re-fetch it every time I visit my Manage Messages web page. The cached response would expire after 5 minutes. If a Message resource is created "behind my back", say by the system admin, it's possible that I won't know about it for up to 5 minutes, until the cached search response expires and is re-fetched. This is acceptable, because it creates no confusion for me. However if I create a new Message resource which I know should be part of the search response, it becomes confusing when it doesn't appear on my Manage Messages page immediately. In general, when I knowingly create/delete/update a resource that invalidates a cached search response, I need that cached response to be expired/flushed immediately. The core problem which I can't figure out: I see no simple way of connecting the task of creating/deleting/updating a resource with the task of expiring the appropriate cached responses. In this example it seems simple, I could manually expire the cached search response whenever I create/delete/update a(ny) Message resource. But in a more complex system, keeping track of which search responses to expire under what circumstances will get clumsy quickly. If someone could suggest a simple solution or some clarifying thoughts, I'd appreciate it.

    Read the article

  • Usability for notification messages, colors

    - by metrobalderas
    In each app I develop, I like to add three types of messages: Green/blue for success messages Yellow for warnings Red for errors And perhaps, a neutral one for information, which is gray or blue if the success one is green. The success one is used for when an item is created or updated, the yellow one is when there's something wrong, but not we-are-going-to-die wrong and the red one is when something is blocked or we are going to die. However, there's one thing I can't figure out, when I delete an object, what kind of notification should I use? I think the success one is not because it is not expected, altough the deletion was successful, the user tends not to read the message, just to see the color. The red one might be, but it can be misunderstood (I tried to delete it but there was an error), the warning and the information one might be good choices, but I'm not really sure. Also, when you ask for confirmation about deleting something, the 'cancel' button should be green or red? I'm just curious how you guys handle this. Thanks.

    Read the article

  • C++: getting the address of the start of an std::vector ?

    - by shoosh
    Sometimes it is useful to use the starting address of an std::vector and temporarily treat that address as the address of a regularly allocated buffer. For instance replace this: char* buf = new char[size]; fillTheBuffer(buf, size); useTheBuffer(buf, size); delete[] buf; With This: vector<char> buf(size); fillTheBuffer(&buf[0], size); useTheBuffer(&buf[0], size); The advantage of this is of course that the buffer is deallocated automatically and I don't have to worry about the delete[]. The problem I'm having with this is when size == 0. In that case the first version works ok. An empty buffer is "allocated" and the subsequent functions do nothing size they get size == 0. The second version however fails if size == 0 since calling buf[0] may rightly contain an assertion that 0 < size. So is there an alternative to the idiom &buf[0] that returns the address of the start of the vector even if the vector is empty? I've also considered using buf.begin() but according to the standard it isn't even guaranteed to return a pointer.

    Read the article

< Previous Page | 159 160 161 162 163 164 165 166 167 168 169 170  | Next Page >