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  • Getting exception when trying to monkey patch pymongo.connection._Pool

    - by Creotiv
    I use pymongo 1.9 on Ubuntu 10.10 with python 2.6.6 When i trying to monkey patch pymongo.connection._Pool i'm getting error on connection: AutoReconnect: could not find master/primary But when i change _Pool class in pymongo.connection module, it work pretty fine. Even if i copy _Pool implementation from pymongo.connection module and will try to monkey patch by the same code, it still giving same exception. I need to remove threading.local from _Pool class, because i use gevent and i need to implement Pool for all mongo connections(for all threads). I use this code: import pymongo class GPool: """A simple connection pool. Uses thread-local socket per thread. By calling return_socket() a thread can return a socket to the pool. Right now the pool size is capped at 10 sockets - we can expose this as a parameter later, if needed. """ # Non thread-locals __slots__ = ["sockets", "socket_factory", "pool_size","sock"] #sock = None def __init__(self, socket_factory): self.pool_size = 10 if not hasattr(self,"sock"): self.sock = None self.socket_factory = socket_factory if not hasattr(self, "sockets"): self.sockets = [] def socket(self): # we store the pid here to avoid issues with fork / # multiprocessing - see # test.test_connection:TestConnection.test_fork for an example # of what could go wrong otherwise pid = os.getpid() if self.sock is not None and self.sock[0] == pid: return self.sock[1] try: self.sock = (pid, self.sockets.pop()) except IndexError: self.sock = (pid, self.socket_factory()) return self.sock[1] def return_socket(self): if self.sock is not None and self.sock[0] == os.getpid(): # There's a race condition here, but we deliberately # ignore it. It means that if the pool_size is 10 we # might actually keep slightly more than that. if len(self.sockets) < self.pool_size: self.sockets.append(self.sock[1]) else: self.sock[1].close() self.sock = None pymongo.connection._Pool = GPool

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  • FIFO dequeueing in python?

    - by Aaron Ramsey
    hello again everybody— I'm looking to make a functional (not necessarily optimally efficient, as I'm very new to programming) FIFO queue, and am having trouble with my dequeueing. My code looks like this: class QueueNode: def __init__(self, data): self.data = data self.next = None def __str__(self): return str(self.data) class Queue: def__init__(self): self.front = None self.rear = None self.size = 0 def enqueue(self, item) newnode = QueueNode(item) newnode.next = None if self.size == 0: self.front = self.rear = newnode else: self.rear = newnode self.rear.next = newnode.next self.size = self.size+1 def dequeue(self) dequeued = self.front.data del self.front self.size = self.size-1 if self.size == 0: self.rear = None print self.front #for testing if I do this, and dequeue an item, I get the error "AttributeError: Queue instance has no attribute 'front'." I guess my function doesn't properly assign the new front of the queue? I'm not sure how to fix it though. I don't really want to start from scratch, so if there's a tweak to my code that would work, I'd prefer that—I'm not trying to minimize runtime so much as just get a feel for classes and things of that nature. Thanks in advance for any help, you guys are the best.

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  • Python beginer having trouble running code

    - by Protean
    For some reason this code will not seem to run in the interpreter. When I hit F5 nothing happens, not even the debugger seems to recognize it. I assume it has something to do with the class, as when removed the interpreter seems to recognize the rest of the code. Please tell me what I am doing wrong. Edit: I have restarted the interpreter multiple times, any other piece of code I try to load runs fine, just this one is having trouble. print ('Why won't this work?') class sorting_class: def __init__(self): self.order = ['a', 'b', 'c', 'd'] self.globali = 0 self.orderi = 0 self.sortedlist = [] def sort(self, array): carry, leave = [] for arrayi in array: print ('run', arrayi) if self.order[self.orderi] == arrayi[self.globali]: carry.append(arrayi) else: if self.globali != 0: leave.append(arrayi) return carry, leave def srt(self, array): globalii = 0 carry, leave = my.sort(array) while len(self.sortedlist) != len(array): if len(self.carry) == 1: self.sortedlist.append(carry) arrayt = leave self.globali = 1 self.orderi = 0 carry, leave = my.sort(arrayt) elif len(self.carry) == 0: if len(self.leave) != 0: arrayt = leave self.globali = 1 self.orderi += 1 my.sort(arrayt) else: self.arrayt globalii += 1 self.orderi = globalii self.globali = 0 my.sort(arrayt) self.orderi = 0 else: arrayt = carry carry = [] self.globali += 1 carry, leave += my.sort(arrayt) my = sorting_class() x = ['ac', 'bc' ,'ab', 'da'] my.srt(x)

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  • Why does my buffered GraphicsContext application have a flickering problem?

    - by Bibendum
    import wx class MainFrame(wx.Frame): def __init__(self,parent,title): wx.Frame.__init__(self, parent, title=title, size=(640,480)) self.mainPanel=DoubleBufferTest(self,-1) self.Show(True) class DoubleBufferTest(wx.Panel): def __init__(self,parent=None,id=-1): wx.Panel.__init__(self,parent,id,style=wx.FULL_REPAINT_ON_RESIZE) self.SetBackgroundColour("#FFFFFF") self.timer = wx.Timer(self) self.timer.Start(100) self.Bind(wx.EVT_TIMER, self.update, self.timer) self.Bind(wx.EVT_PAINT,self.onPaint) def onPaint(self,event): event.Skip() dc = wx.MemoryDC() dc.SelectObject(wx.EmptyBitmap(640, 480)) gc = wx.GraphicsContext.Create(dc) gc.PushState() gc.SetBrush(wx.Brush("#CFCFCF")) bgRect=gc.CreatePath() bgRect.AddRectangle(0,0,640,480) gc.FillPath(bgRect) gc.PopState() dc2=wx.PaintDC(self) dc2.Blit(0,0,640,480,dc,0,0) def update(self,event): self.Refresh() app = wx.App(False) f=MainFrame(None,"Test") app.MainLoop() I've come up with this code to draw double buffered GraphicsContext content onto a panel, but there's a constant flickering across the window. I've tried different kinds of paths, like lines and curves but it's still there and I don't know what's causing it.

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  • How to repeatedly show a Dialog with PyGTK / Gtkbuilder?

    - by Julian
    I have created a PyGTK application that shows a Dialog when the user presses a button. The dialog is loaded in my __init__ method with: builder = gtk.Builder() builder.add_from_file("filename") builder.connect_signals(self) self.myDialog = builder.get_object("dialog_name") In the event handler, the dialog is shown with the command self.myDialog.run(), but this only works once, because after run() the dialog is automatically destroyed. If I click the button a second time, the application crashes. I read that there is a way to use show() instead of run() where the dialog is not destroyed, but I feel like this is not the right way for me because I would like the dialog to behave modally and to return control to the code only after the user has closed it. Is there a simple way to repeatedly show a dialog using the run() method using gtkbuilder? I tried reloading the whole dialog using the gtkbuilder, but that did not really seem to work, the dialog was missing all child elements (and I would prefer to have to use the builder only once, at the beginning of the program). [SOLUTION] As pointed out by the answer below, using hide() does the trick. But one has to take care that the dialog is in fact destroyed if one does not catch its "delete-event". A simple example that works is: import pygtk import gtk class DialogTest: def rundialog(self, widget, data=None): self.dia.show_all() result = self.dia.run() def destroy(self, widget, data=None): gtk.main_quit() def closedialog(self, widget, data=None): self.dia.hide() return True def __init__(self): self.window = gtk.Window(gtk.WINDOW_TOPLEVEL) self.window.connect("destroy", self.destroy) self.dia = gtk.Dialog('TEST DIALOG', self.window, gtk.DIALOG_MODAL | gtk.DIALOG_DESTROY_WITH_PARENT) self.dia.vbox.pack_start(gtk.Label('This is just a Test')) self.dia.connect("delete-event", self.closedialog) self.button = gtk.Button("Run Dialog") self.button.connect("clicked", self.rundialog, None) self.window.add(self.button) self.button.show() self.window.show() if __name__ == "__main__": testApp = DialogTest() gtk.main()

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  • Which class should store the lookup table?

    - by max
    The world contains agents at different locations, with only a single agent at any location. Each agent knows where he's at, but I also need to quickly check if there's an agent at a given location. Hence, I also maintain a map from locations to agents. I have a problem deciding where this map belongs to: class World, class Agent (as a class attribute) or elsewhere. In the following I put the lookup table, agent_locations, in class World. But now agents have to call world.update_agent_location every time they move. This is very annoying; what if I decide later to track other things about the agents, apart from their locations - would I need to add calls back to the world object all across the Agent code? class World: def __init__(self, n_agents): # ... self.agents = {} self.agent_locations = {} for id in range(n_agents): x, y = self.find_location() agent = Agent(self,x,y) self.agents.append(agent) self.agent_locations[x,y] = agent def update_agent_location(self, agent, x, y): del self.agent_locations[agent.x, agent.y] self.agent_locations[x, y] = agent def update(self): # next step in the simulation for agent in self.agents: agent.update() # next step for this agent # ... class Agent: def __init__(self, world, x, y): self.world = world self.x, self.y = x, y def move(self, x1, y1): self.world.update_agent_location(self, x1, y1) self.x, self.y = x1, y1 def update(): # find a good location that is not occupied and move there for x, y in self.valid_locations(): if not self.location_is_good(x, y): continue if self.world.agent_locations[x, y]: # location occupied continue self.move(x, y) I can instead put agent_locations in class Agent as a class attribute. But that only works when I have a single World object. If I later decide to instantiate multiple World objects, the lookup tables would need to be world-specific. I am sure there's a better solution... EDIT: I added a few lines to the code to show how agent_locations is used. Note that it's only used from inside Agent objects, but I don't know if that would remain the case forever.

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  • Problem inserting Pygames on a wxPython panel using Boa Constructor

    - by Kohwalter
    Hello, im new in Python so im hoping to to get some help to figure out what is going wrong. Im trying to run a Pygames from within wxPython panel (made on Boa Constructor). To do that i followed the instructions on the http://wiki.wxpython.org/IntegratingPyGame but still it isn't working. Here is the Panel code that was used to make the integration: class PG_panel(wx.Panel): def __init__(self, ID, name, parent, mypos, mysize): # pygame is imported in this class # make it globally available global pygame #self.Fit() wx.Panel.__init__(self, id=wxID_FRMMAINPANELTABULEIRO, name='panelTabuleiro', parent=self, pos=(16, 96), size=mysize) # pygame uses SDL, set the environment variables os.environ['SDL_WINDOWID'] = str(self.GetHandle()) os.environ['SDL_VIDEODRIVER'] = 'windib' # do the pygame stuff after setting the environment variables import pygame pygame.display.init() # create the pygame window/screen screen = pygame.display.set_mode(464, 464) #(424,450) # start the thread instance self.thread = PG_thread(screen) self.thread.start() def __del__(self): self.thread.stop() And im trying to use that panel on an interface from Boa Constructor, here is the code: class frmMain(wx.Frame): def _init_ctrls(self, prnt): # generated method, don't edit wx.Frame.__init__(self, id=wxID_FRMMAIN, name='frmMain', parent=prnt, pos=wx.Point(660, 239), size=wx.Size(815, 661), style=wx.DEFAULT_FRAME_STYLE, title='Grupo 1 - Jogo de Damas') self._init_utils() self.SetClientSize(wx.Size(799, 623)) self.SetBackgroundColour(wx.Colour(225, 225, 225)) self.SetMinSize(wx.Size(784, 650)) self.Center(wx.BOTH) self.SetMenuBar(self.menuBar1) #here begins my code mysize = (464, 464) mypos = (16, 96) self.panelTabuleiro = PG_panel(wxID_FRMMAINPANELTABULEIRO, 'panelTabuleiro', self, mypos, mysize) The original that was auto-made by the Boa Constructor is the following: self.panelTabuleiro = wx.Panel(id=wxID_FRMMAINPANELTABULEIRO, name='panelTabuleiro', parent=self, pos=wx.Point(16, 96), size=wx.Size(464, 464), style=wx.TAB_TRAVERSAL) self.panelTabuleiro.SetBackgroundColour(wx.Colour(232, 249, 240)) self.panelTabuleiro.SetThemeEnabled(True) self.panelTabuleiro.SetHelpText('Tabuleiro') The error that it gives is: Type error: in method 'new_Panel', expected argument 1 of type 'wxWindow*1 Exception AttributeError: "'PG_panel' object has no attribute 'thread' in ignored Any thoughts ? I appreciate any help. Thank you.

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  • how to use listctrl in notebook wxPython

    - by ???
    I have one question.. wxPython listctrl in notebook I created 2 tab use notebook. I added button in first tab and added Listctrl in second tab. If i click the button, Add value in Listctrl to second tab. how to solve this problem? import wx class PageOne(wx.Panel): def __init__(self, parent): wx.Panel.__init__(self, parent) self.query_find_btn = wx.Button(self, 4, "BTN", (40,40)) self.Bind(wx.EVT_BUTTON, self.AddList, id = 4) def AddList(self, evt): self.list1.InsertStringItem(0,'Hello') class PageTwo(wx.Panel): def __init__(self, parent): wx.Panel.__init__(self, parent) self.list1 = wx.ListCtrl(self,-1,wx.Point(0,0),wx.Size(400,400),style=wx.LC_REPORT | wx.SUNKEN_BORDER) self.list1.InsertColumn(0,'values') class MyFrame(wx.Frame): def __init__(self, parent, id, title): wx.Frame.__init__(self,parent,id,title,size=(400,400),pos=wx.Point(100,100), style=wx.SYSTEM_MENU |wx.CAPTION ) p = wx.Panel(self) nb = wx.Notebook(p) MainFrame = PageOne(nb) SecondFrame = PageTwo(nb) nb.AddPage(MainFrame, "One") nb.AddPage(SecondFrame, "Two") sizer = wx.BoxSizer() sizer.Add(nb, 1, wx.EXPAND) p.SetSizer(sizer) class MyApp(wx.App): def OnInit(self): self.frame=MyFrame(None,-1,'Unknown.py') self.frame.Centre() self.frame.Show() return True if __name__ == '__main__': app = MyApp(False) app.MainLoop()

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  • Can't remove first node in linked list

    - by carlmonday
    I'm trying to make a linked list class in python (pointless I know, but it's a learning exercise), and the method I have written to remove a node doesn't work if I try to remove the first element of the linked list. If the node to be removed is anywhere else in the linked list the method works fine. Can someone give me some insight as to where I've gone wrong? Here's my code thus far: class Node: def __init__(self, data=None, next=None): self.data = data self.next = next def __repr__(self): return repr(self.data) def printNodes(self): while self: print self.data self = self.next def removeNode(self, datum): """removes node from linked list""" if self.data == datum: return self.next while self.next: if self.next.data == datum: self.next = self.next.next return self self = self.next

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  • sybase - values from one table that aren't on another, on opposite ends of a 3-table join

    - by Lazy Bob
    Hypothetical situation: I work for a custom sign-making company, and some of our clients have submitted more sign designs than they're currently using. I want to know what signs have never been used. 3 tables involved: table A - signs for a company sign_pk(unique) | company_pk | sign_description 1 --------------------1 ---------------- small 2 --------------------1 ---------------- large 3 --------------------2 ---------------- medium 4 --------------------2 ---------------- jumbo 5 --------------------3 ---------------- banner table B - company locations company_pk | company_location(unique) 1 ------|------ 987 1 ------|------ 876 2 ------|------ 456 2 ------|------ 123 table C - signs at locations (it's a bit of a stretch, but each row can have 2 signs, and it's a one to many relationship from company location to signs at locations) company_location | front_sign | back_sign 987 ------------ 1 ------------ 2 987 ------------ 2 ------------ 1 876 ------------ 2 ------------ 1 456 ------------ 3 ------------ 4 123 ------------ 4 ------------ 3 So, a.company_pk = b.company_pk and b.company_location = c.company_location. What I want to try and find is how to query and get back that sign_pk 5 isn't at any location. Querying each sign_pk against all of the front_sign and back_sign values is a little impractical, since all the tables have millions of rows. Table a is indexed on sign_pk and company_pk, table b on both fields, and table c only on company locations. The way I'm trying to write it is along the lines of "each sign belongs to a company, so find the signs that are not the front or back sign at any of the locations that belong to the company tied to that sign." My original plan was: Select a.sign_pk from a, b, c where a.company_pk = b.company_pk and b.company_location = c.company_location and a.sign_pk *= c.front_sign group by a.sign_pk having count(c.front_sign) = 0 just to do the front sign, and then repeat for the back, but that won't run because c is an inner member of an outer join, and also in an inner join. This whole thing is fairly convoluted, but if anyone can make sense of it, I'll be your best friend.

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  • Self-healing Cloud vs Failover Boxes

    - by IMB
    Now that self-healing cloud servers are becoming more and more popular, I am currently torn between the decision if I should setup a HAproxy failover for my VPS or if should save myself the trouble and just put my sites on a self-healing cloud server. Does it still make sense to setup your own failover system (HAproxy + 2 or more servers for example) when self healing cloud seems like a practical solution? They seem to do the same job or am I missing something?

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  • join condition depends on the parameter

    - by sunglim
    Hi. I'm a sql newbie, I use mssql2005 I like to do join Action depnding on input parameter. CREATE PROCEDURE SelectPeriodicLargeCategoryData @CATEGORY_LEVEL CHAR(1), @CATEGORY_CODE VARCHAR(9) AS ... JOIN CATEGORY_AD_SYS CAS WITH(NOLOCK) ON CA.CATEGORY_ID = [[[[[ HERE ]]]] above the sql. if @CATEGORY_LEVEL = 'L' then I like to join on CAS.LCATEGORY else if @CATEGORY_LEVEL = 'M' then I like to join on CAS.MCATEGORY else if @CATEGORY_LEVEL = 'S' then I like to join on CAS.SCATEGORY ... how can I do this?

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  • Help With LINQ: Mixed Joins and Specifying Default Values

    - by Corey O.
    I am trying to figure out how to do a mixed-join in LINQ with specific access to 2 LINQ objects. Here is an example of how the actual TSQL query might look: SELECT * FROM [User] AS [a] INNER JOIN [GroupUser] AS [b] ON [a].[UserID] = [b].[UserID] INNER JOIN [Group] AS [c] ON [b].[GroupID] = [c].[GroupID] LEFT JOIN [GroupEntries] AS [d] ON [a].[GroupID] = [d].[GroupID] WHERE [a].[UserID] = @UserID At the end, basically what I would like is an enumerable object full of GroupEntry objects. What am interested is the last two tables/objects in this query. I will be displaying Groups as a group header, and all of the Entries underneath their group heading. If there are no entries for a group, I still want to see that group as a header without any entries. Here's what I have so far: So from that I'd like to make a function: public void DisplayEntriesByUser(int user_id) { MyDataContext db = new MyDataContext(); IEnumberable<GroupEntries> entries = ( from user in db.Users where user.UserID == user_id join group_user in db.GroupUsers on user.UserID = group_user.UserID into a from join1 in a join group in db.Groups on join1.GroupID equals group.GroupID into b from join2 in b join entry in db.Entries.DefaultIfEmpty() on join2.GroupID equals entry.GroupID select entry ); Group last_group_id = 0; foreach(GroupEntry entry in entries) { if (last_group_id == 0 || entry.GroupID != last_group_id) { last_group_id = entry.GroupID; System.Console.WriteLine("---{0}---", entry.Group.GroupName.ToString().ToUpper()); } if (entry.EntryID) { System.Console.WriteLine(" {0}: {1}", entry.Title, entry.Text); } } } The example above does not work quite as expected. There are 2 problems that I have not been able to solve: I still seem to be getting an INNER JOIN instead of a LEFT JOIN on the last join. I am not getting any empty results, so groups without entries do not appear. I need to figure out a way so that I can fill in the default values for blank sets of entries. That is, if there is a group without an entry, I would like to have a mostly blank entry returned, except that I'd want the EntryID to be null or 0, the GroupID to be that of of the empty group that it represents, and I'd need a handle on the entry.Group object (i.e. it's parent, empty Group object). Any help on this would be greatly appreciated. Note: Table names and real-world representation were derived purely for this example, but their relations simplify what I'm trying to do.

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  • left join on linq

    - by ognjenb
    SQL: FROM `order` o LEFT JOIN person d ON o.`DistributorId` = d.`Id` LEFT JOIN person c ON o.`CustomerId` = c.Id LEFT JOIN Transporter t ON o.`TransporterId` = t.Id LEFT JOIN IbekoEngineer e ON o.OrderEnteredBy = e.Id In any way to translate this 4 left join to LINQ query

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  • Self referencing userdata and garbage collection

    - by drtwox
    Because my userdata objects reference themselves, I need to delete and nil a variable for the garbage collector to work. Lua code: obj = object:new() -- -- Some time later obj:delete() -- Removes the self reference obj = nil -- Ready for collection C Code: typedef struct { int self; // Reference to the object // Other members and function references removed } Object; // Called from Lua to create a new object static int object_new( lua_State *L ) { Object *obj = lua_newuserdata( L, sizeof( Object ) ); // Create the 'self' reference, userdata is on the stack top obj->self = luaL_ref( L, LUA_REGISTRYINDEX ); // Put the userdata back on the stack before returning lua_rawgeti( L, LUA_REGISTRYINDEX, obj->self ); // The object pointer is also stored outside of Lua for processing in C return 1; } // Called by Lua to delete an object static int object_delete( lua_State *L ) { Object *obj = lua_touserdata( L, 1 ); // Remove the objects self reference luaL_unref( L, LUA_REGISTRYINDEX, obj->self ); return 0; } Is there some way I can set the object to nil in Lua, and have the delete() method called automatically? Alternatively, can the delete method nil all variables that reference the object? Can the self reference be made 'weak'?

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  • Changing pointer of self

    - by rob5408
    I have an object that I alloc/init like normal just to get a instance. Later in my application I want to load state from disk for that object. I figure I could unarchive my class (which conforms to NSCoding) and just swap where my instance points to. To this end I use this code... NSString* pathForDataFile = [self pathForDataFile]; if([[NSFileManager defaultManager] fileExistsAtPath:pathForDataFile] == YES) { NSLog(@"Save file exists"); NSData *data = [[NSMutableData alloc] initWithContentsOfFile:pathForDataFile]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; [data release]; Person *tempPerson = [unarchiver decodeObjectForKey:@"Person"]; [unarchiver finishDecoding]; [unarchiver release]; if (tempPerson) { [self release]; self = [tempPerson retain]; } } Now when I sprinkled some NSLogs throughout my application I noticed self.person: <Person: 0x3d01a10> (After I create the object with alloc/init) self: <Person: 0x3d01a10> (At the start of this method) tempPerson: <Person: 0x3b1b880> (When I create the tempPerson) self: <Person: 0x3b1b880> (after i point self to the location of the tempPerson) self.person: <Person: 0x3d01a10> (After the method back in the main program) What am I missing?

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  • How do I avoid a repetitive subquery JOIN in SQL?

    - by Karl
    Hi In SQL Server 2008: I have one table, and I want to do something along the following lines: SELECT T1.stuff, T2.morestuff from ( SELECT code, date1, date2 from Table ) as T1 INNER JOIN ( SELECT code, date1, date2 from Table ) as T2 ON T1.code = T2.code and T1.date1 = T2.date2 The two subqueries are exactly identical. Is there any way I can do this without repeating the subquery script? Thanks Karl

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  • Why does this Grails/HQL query with a JOIN return Lists of pairs of domain classes?

    - by ?????
    I'm having trouble figuring out how to do a "join" in Groovy/Grails and the return values I get person = User.get(user.id) def latestPhotosForUser = PhotoOwner.findAll("FROM PhotoOwner AS a, PhotoStorage AS b WHERE (a.owner=:person AND a.photo = b)", [person:person], [max:3]) latestPhotosForUser isn't a list of PhotoOwners. It's a list of [PhotoOwner, PhotoStorage] pairs. Since I'm doing a PhotoOwner.findAll, I would have expected to see only PhotoOwners. Am I doing something wrong, or is this the proper behavior?

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  • Is this Where condition in Linq-to-sql join correct?

    - by Pandiya Chendur
    I have the following Iqueryable method to show details of a singl material, public IQueryable<Materials> GetMaterial(int id) { return from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id where m.Mat_id equals id select new Materials() { Id = Convert.ToInt64(m.Mat_id), Mat_Name = m.Mat_Name, Mes_Name = Mt.Name, }; } Any suggestion....

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  • Cannot have a qualifier in the select list while performing a JOIN w/ USING keyword.

    - by JuiceBerry123
    I am looking at a practice test that doesn't have explanations about the correct answers. The question I'm confused about basically asks why the following SQL statement can never work: SELECT oi.order_id, product_jd, order_date FROM order_items oi JOIN orders o USING(order_id); The answer it gave was: "The statement would not execute because the column part of the USING clause cannot have a qualifier in the SELECT list" Can someone elaborate on this? I am pretty stumped.

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  • SQL Server CTE referred in self joins slow

    - by Kharlos Dominguez
    Hello, I have written a table-valued UDF that starts by a CTE to return a subset of the rows from a large table. There are several joins in the CTE. A couple of inner and one left join to other tables, which don't contain a lot of rows. The CTE has a where clause that returns the rows within a date range, in order to return only the rows needed. I'm then referencing this CTE in 4 self left joins, in order to build subtotals using different criterias. The query is quite complex but here is a simplified pseudo-version of it WITH DataCTE as ( SELECT [columns] FROM table INNER JOIN table2 ON [...] INNER JOIN table3 ON [...] LEFT JOIN table3 ON [...] ) SELECT [aggregates_columns of each subset] FROM DataCTE Main LEFT JOIN DataCTE BananasSubset ON [...] AND Product = 'Bananas' AND Quality = 100 LEFT JOIN DataCTE DamagedBananasSubset ON [...] AND Product = 'Bananas' AND Quality < 20 LEFT JOIN DataCTE MangosSubset ON [...] GROUP BY [ I have the feeling that SQL Server gets confused and calls the CTE for each self join, which seems confirmed by looking at the execution plan, although I confess not being an expert at reading those. I would have assumed SQL Server to be smart enough to only perform the data retrieval from the CTE only once, rather than do it several times. I have tried the same approach but rather than using a CTE to get the subset of the data, I used the same select query as in the CTE, but made it output to a temp table instead. The version referring the CTE version takes 40 seconds. The version referring the temp table takes between 1 and 2 seconds. Why isn't SQL Server smart enough to keep the CTE results in memory? I like CTEs, especially in this case as my UDF is a table-valued one, so it allowed me to keep everything in a single statement. To use a temp table, I would need to write a multi-statement table valued UDF, which I find a slightly less elegant solution. Did some of you had this kind of performance issues with CTE, and if so, how did you get them sorted? Thanks, Kharlos

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  • Does clustered index on foreign key column increase join performance vs non-clustered ?

    - by alpav
    In many places it's recommended that clustered indexes are better utilized when used to select range of rows using BETWEEN statement. When I select joining by foreign key field in such a way that this clustered index is used, I guess, that clusterization should help too because range of rows is being selected even though they all have same clustered key value and BETWEEN is not used. Considering that I care only about that one select with join and nothing else, am I wrong with my guess ?

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  • How can I use "FOR UPDATE" with a JOIN on Oracle?

    - by tangens
    The answer to another SO question was to use this SQL query: SELECT o.Id, o.attrib1, o.attrib2 FROM table1 o JOIN ( SELECT DISTINCT Id FROM table1, table2, table3 WHERE ... ) T1 ON o.id = T1.Id Now I wonder how I can use this statement together with the keyword FOR UPDATE. If I simply append it to the query, Oracle will tell me: ORA-02014: cannot select FOR UPDATE from view Do I have to modify the query or is there a trick to do this with Oracle? With MySql the statement works fine.

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  • Is a JOIN more/less efficient than EXISTS IN when no data is needed from the second table?

    - by twpc
    I need to look up all households with orders. I don't care about the data of the order at all, just that it exists. Is it more efficient to say something like this: SELECT HouseholdID, LastName, FirstName, Phone FROM Households INNER JOIN Orders ON Orders.HouseholdID = Households.HouseholdID or this: SELECT HouseholdID, LastName, FirstName, Phone FROM Households WHERE EXISTS (SELECT HouseholdID FROM Orders WHERE Orders.HouseholdID = Households.HouseholdID)

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