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  • Speeding up inner joins between a large table and a small table

    - by Zaid
    This may be a silly question, but it may shed some light on how joins work internally. Let's say I have a large table L and a small table S (100K rows vs. 100 rows). Would there be any difference in terms of speed between the following two options?: OPTION 1: OPTION 2: --------- --------- SELECT * SELECT * FROM L INNER JOIN S FROM S INNER JOIN L ON L.id = S.id; ON L.id = S.id; Notice that the only difference is the order in which the tables are joined. I realize performance may vary between different SQL languages. If so, how would MySQL compare to Access?

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  • Symbols taking very, very long time to load when hosting ASP.NET app in IIS

    - by joshcomley
    Hi, I'm hosting my project using IIS, running from Visual Studio. Whenever I recompile, on the first run it takes several minutes (on a not awful machine) to load all the symbols. Please see http://joshz.com/so/symbols.html for a list of the symbols that are loaded. At the bottom there is a ThreadAbortException, I'm not sure if this is playing a role. Any advice would be greatly appreciated; it's slowing my day down enormously! As a note: the project has never run quickly since I joined the company and started working with it.

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  • Casting array of pointers to objects

    - by ritmbo
    If B is subclass of A. And I have in main(): B** b = new B*[10]; ... some algorithm that do b[i] = new B(..); ... So I have an array of pointers to objets B. Then I have a function: void f(A** foo); If in main, I do: f(b); I get a warning, but obviously if I do: f((A**)b);, i dont. The (A**) its a bit nasty. I was wondering if there's a more elegant way in C++ that at least do type checking as dynamic_cast.

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  • Join a single row in one table to n random rows in another

    - by Einar Egilsson
    Is it possible to make a join in SQL server that joins each row from table A to n random rows in another? For example, say I have a Customer table, a Product table and an Order table. I want to join each customer to 5 random products and insert these rows into the order table. (And each customer should be joined to 5 random rows of his own, I don't want all customers joining to the same 5 rows). Is this possible? I'm using SQL Server 2005 and it's fine if the solution is specific to that. This is a weird requirement but I'm basically making a small data generator to generate some random data.

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  • Java generics: Illegal forward reference

    - by Arian
    Given a generic interface interface Foo<A, B> { } I want to write an implementation that requires A to be a subclass of B. So I want to do class Bar<A, B super A> implements Foo<A, B> { } // --> Syntax error or class Bar<A extends B, B> implements Foo<A, B> { } // --> illegal forward reference But the only solution that seems to work is this: class Bar<B, A extends B> implements Foo<A, B> { } which is kind of ugly, because it reverses the order of the generic parameters. Are there any solutions or workarounds to this problem?

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  • More strict query yields more results?

    - by Mark
    I've got a query that looks like this affiliates = User.objects.annotate(referral_count=Count('referrals')).filter(referral_count__gt=0) But when I restrict it more by adding referrals__user__date_joined__gt=start_date to the filter, I get even higher referral counts. I'm trying to count the number of people a user has referred within a time period. The relevant model looks like this: class Profile(models.Model): user = models.ForeignKey(User, unique=True, related_name='profile') referred_by = models.ForeignKey(User, null=True, blank=True, related_name='referrals') In contrast, when I try it like this: affiliates = User.objects \ .exclude(referrals__user__date_joined__lte=sd, referrals__user__date_joined__gt=ed) \ .annotate(referral_count=Count('referrals')) \ .filter(referral_count__gt=0) The exclude statement seems to do nothing... the counts don't change (should be 0 if no referred users have joined within that time period, but it isn't).

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  • Extract Generic types from extended Generic

    - by Brigham
    I'm trying to refactor a class and set of subclasses where the M type does extend anything, even though we know it has to be a subclass of a certain type. That type is parametrized and I would like its parametrized types to be available to subclasses that already have values for M. Is there any way to define this class without having to include the redundant K and V generic types in the parameter list. I'd like to be able to have the compiler infer them from whatever M is mapped to by subclasses. public abstract class NewParametrized<K, V, M extends SomeParametrized<K, V>> { public void someMethodThatTakesKAndV(K k1, V v1) { } } In other words, I'd like the class declaration to look something like: public class NewParametrized<M extends SomeParametrized<K, V>> { And K and V's types would be inferred from the definition of M.

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  • How to perform a non-polymorphic HQL query in Hibernate?

    - by Eli Acherkan
    Hi all, I'm using Hibernate 3.1.1, and in particular, I'm using HQL queries. According to the documentation, Hibernate's queries are polymorphic: A query like: from Cat as cat returns instances not only of Cat, but also of subclasses like DomesticCat. How can I query for instances of Cat, but not of any of its subclasses? I'd like to be able to do it without having to explicitly mention each subclass. I'm aware of the following options, and don't find them satisfactory: Manually filtering the instances after the query, OR: Manually adding a WHERE clause on the discriminator column. It would make sense for Hibernate to allow the user to decide whether a query should be polymorphic or not, but I can't find such an option. Thanks in advance!

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  • What is the typical method to separate connected letters in a word using OCR

    - by Maysam
    I am very new to OCR and almost know nothing about the algorithms used to recognize words. I am just getting familiar to that. Could anybody please advise on the typical method used to recognize and separate individual characters in connected form (I mean in a word where all letters are linked together)? Forget about handwriting, supposing the letters are connected together using a known font, what is the best method to determine each individual character in a word? When characters are written separately there is no problem, but when they are joined together, we should know where every single character starts and ends in order to go to the next step and match them individually with a letter. Is there any known algorithm for that?

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  • SQL join to grab data from same table via intermediate table

    - by Sergio
    Hi Could someone help me with building the following query. I have a table called Sites, and one called Site_H. The two are joined by a foreign key relationship on page_id. So the Sites table contains pages, and the Site_H table shows which pages any given page is a child of by having another foreign key relation back to the site table with a column called ParentOf. So, a page can be have another page as a parent. Other data is stored in the Site_H table such as position etc, hence why it is separated out. I would like a query that returns the details of a page along with the details of its parent page. I just cant quite think about how to structure the SQL. Thanks

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  • Python New-style Classes and the Super Function

    - by sfjedi
    This is not the result I expect to see: class A(dict): def __init__(self, *args, **kwargs): self['args'] = args self['kwargs'] = kwargs class B(A): def __init__(self, *args, **kwargs): super(B, self).__init__(args, kwargs) print 'Instance A:', A('monkey', banana=True) #Instance A: {'args': ('monkey',), 'kwargs': {'banana': True}} print 'Instance B:', B('monkey', banana=True) #Instance B: {'args': (('monkey',), {'banana': True}), 'kwargs': {}} I'm just trying to get classes A and B to have consistent values set. I'm not sure why the kwargs are being inserted into the args, but I'm to presume I am either calling init() wrong from the subclass or I'm trying to do something that you just can't do. Any tips?

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  • Constructor invocation returned null: what to do?

    - by strager
    I have code which looks like: private static DirectiveNode CreateInstance(Type nodeType, DirectiveInfo info) { var ctor = nodeType.GetConstructor(new[] { typeof(DirectiveInfo) }); if(ctor == null) { throw new MissingMethodException(nodeType.FullName, "ctor"); } var node = ctor.Invoke(new[] { info }) as DirectiveNode; if(node == null) { // ???; } return node; } I am looking for what to do (e.g. what type of exception to throw) when the Invoke method returns something which isn't a DirectiveNode or when it returns null (indicated by // ??? above). (By the method's contract, nodeType will always describe a subclass of DirectiveNode.) I am not sure when calling a constructor would return null, so I am not sure if I should handle anything at all, but I still want to be on the safe side and throw an exception if something goes wrong.

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  • In an Android test, how to check that a View is shown?

    - by Jan Zankowski
    Hello, I'm writing a UI test case (using ActivityUnitTestCase) and would like to check if at a given time a View subclass is visible to the user. I've found the View#isShown() method, which claims to do exactly this - checking the visibility field of this element and all its parents - but somehow it always returns "false" for all the elements. I'll be grateful for some help. If it makes it easier, I can paste some code. Also, I found ViewAsserts#assertOnScreen(View origin, View view) but it doesn't seem to do the right thing either - always returns true. Am I perhaps calling it wrong: assertOnScreen(viewImTesting.getRootView(), viewImTesting)? Thanks, Jan

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  • Constructor invokation returned null: what to do?

    - by strager
    I have code which looks like: private static DirectiveNode CreateInstance(Type nodeType, DirectiveInfo info) { var ctor = nodeType.GetConstructor(new[] { typeof(DirectiveInfo) }); if(ctor == null) { throw new MissingMethodException(nodeType.FullName, "ctor"); } var node = ctor.Invoke(new[] { info }) as DirectiveNode; if(node == null) { // ???; } return node; } I am looking for what to do (e.g. what type of exception to throw) when the Invoke method returns something which isn't a DirectiveNode or when it returns null (indicated by // ??? above). (By the method's contract, nodeType will always describe a subclass of DirectiveNode.) I am not sure when calling a constructor would return null, so I am not sure if I should handle anything at all, but I still want to be on the safe side and throw an exception if something goes wrong.

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  • PHP or C# script to parse CSV table values to fill in one-to-many table

    - by Yaaqov
    I'm looking for an example of how to split-out comma-delimited data in a field of one table, and fill in a second table with those individual elements, in order to make a one-to-many relational database schema. This is probably really simple, but let me give an example: I'll start with everything in one table, Widgets, which has a "state" field to contain states that have that widget: Table: WIDGET =============================== | id | unit | states | =============================== |1 | abc | AL,AK,CA | ------------------------------- |2 | lmn | VA,NC,SC,GA,FL | ------------------------------- |3 | xyz | KY | =============================== Now, what I'd like to create via code is a second table to be joined to WIDGET called *Widget_ST* that has widget id, widget state id, and widget state name fields, for example Table: WIDGET_ST ============================== | w_id | w_st_id | w_st_name | ------------------------------ |1 | 1 | AL | |1 | 2 | AK | |1 | 3 | CA | |2 | 1 | VA | |2 | 2 | NC | |2 | 1 | SC | |2 | 2 | GA | |2 | 1 | FL | |3 | 1 | KY | ============================== I am learning C# and PHP, so responses in either language would be great. Thanks.

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  • OWL inferencing question

    - by user439170
    I am using the Jena semantic web framework version 2.6.3. I have code that creates a model with owl inferencing and then adds the following triples: [:bnode-3 rdf:type owl:Restriction] [:bnode-3 owl:onProperty :offspringOf] [:bnode-3 owl:someValuesFrom :Person] [:bnode-3 rdfs:subClassOf :Person] bnode-3 is supposed to be a restriction class which, for example, would contain :joe if :bob is a :Person and the following triple were asserted: [:joe :offspringOf :bob]. Then, since the restriction class is a subclass of Person, :joe would also be a person. And, in fact, this works. Whats confusing to me is that after I assert just the 4 triples at the top of this post, the inferencer creates a blank node which is a Person. In other words, the following triple is now in the model: [_:b0 rdf:type :Person] I don't understand why it would do this. Any help in understanding this would be greatly appreciated. Thanks. Kent.

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  • Table not Echoing out if another Table has a Zero value

    - by John
    Hello, The table below with mysql_query($sqlStr3) (the one with the word "Joined" in its row) does not echo if the result associated with mysql_query($sqlStr1) has a value of zero. This happens even if mysql_query($sqlStr3) returns a result. In other words, if a given loginid has an entry in the table "login", but not one in the table "submission", then the table associated with mysql_query($sqlStr3) does not echo. I don't understand why the "submission" table would have any effect on mysql_query($sqlStr3), since the $sqlStr3 only deals with another table, called "login", as seen below. Any ideas why this is happening? Thanks in advance, John W. <?php echo '<div class="profilename">User Profile for </div>'; echo '<div class="profilename2">'.$profile.'</div>'; $tzFrom = new DateTimeZone('America/New_York'); $tzTo = new DateTimeZone('America/Phoenix'); $profile = mysql_real_escape_string($_GET['profile']); $sqlStr = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl FROM submission AS s INNER JOIN login AS l ON s.loginid = l.loginid WHERE l.username = '$profile' ORDER BY s.datesubmitted DESC"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec1\">"; while ($row = mysql_fetch_array($result)) { $dt = new DateTime($row["datesubmitted"], $tzFrom); $dt->setTimezone($tzTo); echo '<tr>'; echo '<td class="sitename3">'.$dt->format('F j, Y &\nb\sp &\nb\sp g:i a').'</a></td>'; echo '<td class="sitename1"><a href="http://www.'.$row["url"].'">'.$row["title"].'</a></td>'; echo '</tr>'; } echo "</table>"; $sqlStr1 = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl, l.created, count(s.submissionid) countSubmissions FROM submission AS s INNER JOIN login AS l ON s.loginid = l.loginid WHERE l.username = '$profile'"; $result1 = mysql_query($sqlStr1); $arr1 = array(); echo "<table class=\"samplesrec2\">"; while ($row1 = mysql_fetch_array($result1)) { echo '<tr>'; echo '<td class="sitename5">Submissions: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$row1["countSubmissions"].'</td>'; echo '</tr>'; } echo "</table>"; $sqlStr2 = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented, l.created, count(c.commentid) countComments FROM comment AS c INNER JOIN login AS l ON c.loginid = l.loginid WHERE l.username = '$profile'"; $result2 = mysql_query($sqlStr2); $arr2 = array(); echo "<table class=\"samplesrec3\">"; while ($row2 = mysql_fetch_array($result2)) { echo '<tr>'; echo '<td class="sitename5">Comments: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$row2["countComments"].'</td>'; echo '</tr>'; } echo "</table>"; $tzFrom3 = new DateTimeZone('America/New_York'); $tzTo3 = new DateTimeZone('America/Phoenix'); $sqlStr3 = "SELECT created, username FROM login WHERE username = '$profile'"; $result3 = mysql_query($sqlStr3); $arr3 = array(); echo "<table class=\"samplesrec4\">"; while ($row3 = mysql_fetch_array($result3)) { $dt3 = new DateTime($row3["created"], $tzFrom3); $dt3->setTimezone($tzTo3); echo '<tr>'; echo '<td class="sitename5">Joined: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'.$dt->format('F j, Y').'</td>'; echo '</tr>'; } echo "</table>"; ?> </body> </html>

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  • Create custom component based on LinearLayout, declaring layout in XML

    - by pheelicks
    I've been trying to create a Compound Control in Android 1.5 (as described here) but havn't been able to find any good examples on how to do this using an XML file to specify a layout. I'm fine with creating an Activity and then loading an xml file using the following in the constructor: setContentView(R.layout.main); However, I want to do this in subclass of LinearLayout - so I can use this compound component in other XML layouts. Something along the lines of: public class CustomView extends LinearLayout { public CustomView(Context context) { super(context); setupView(); } public CustomView(Context context, AttributeSet attrs) { super(context, attrs); setupView(); } public void setupView() { setContentView(R.layout.custom); // Not possible } } What is the correct way of going about doing this?

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  • Python: Why Does a Method Behave Differently with an Added Parameter?

    - by SteveStifler
    I have a method in a Pygame Sprite subclass, defined as such: def walk(self): """move across screen""" displacement = self.rect.move((self.move, 0)) if self.rect.left < self.area.left or self.rect.right > self.area.right: self.move = -self.move displacement = self.rect.move((self.move, 0)) self.rect = displacement I modified it, adding a parameter speed_x, and now the program is broken. def walk(self, speed_x): """move across screen""" displacement = self.rect.move((speed_x, 0)) if self.rect.left < self.area.left or self.rect.right > self.area.right: speed_x = -speed_x displacement = self.rect.move((speed_x, 0)) self.rect = displacement Before I called the method like this: def update(self): self.walk() Now I do: def update(self): self.walk(self.move) Why doesn't this work?

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  • How to string multiple TextReaders together?

    - by Ken
    I have 3 TextReaders -- a combination of StreamReaders and StringReaders. Conceptually, the concatenation of them is a single text document. I want to call a method (not under my control) that takes a single TextReader. Is there any built-in or easy way to make a concatenating TextReader from multiple TextReaders? (I could write my own TextReader subclass, but it looks like a fair amount of work. In that case, I'd just write them all out to a temp file and then open it with a single StreamReader.) Is there an easy solution to this that I'm missing?

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  • Where to put conditionals in ANSI-syntax SQL queries

    - by RenderIn
    What's the difference between these two queries? I've been resistant to jumping on the ANSI-syntax bandwagon because I have not been able to unravel various syntactical ambiguities. Is 1) returning the product of the join and only then filtering out those joined records which have weight = 500? And is 2) filtering out those prior to the join? Is 2 bad syntax? Why might I use that? 1: SELECT SOMETHING FROM FOO INNER JOIN BAR ON FOO.NAME = BAR.NAME WHERE BAR.WEIGHT < 500 2: SELECT SOMETHING FROM FOO INNER JOIN BAR ON FOO.NAME = BAR.NAME AND BAR.WEIGHT < 500

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  • How to observe NSScroller changes?

    - by Paperflyer
    I have an NSScrollView subclass and I would like to update another NSView based on the current scroll position. I tried KVC-observing the value of [self horizontalScroller] but that never gets called. // In awakeFromNib [[self horizontalScroller] addObserver:self forKeyPath:@"value" options:NSKeyValueObservingOptionNew context:NULL]; // Later in the file - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (object == [self horizontalScroller] && [keyPath isEqualToString:@"value"]) { // This never gets called } } Do you see an error in my reasoning or know a better method of how to observe the scrolling of an NSScrollview?

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  • correct way to store an exception in a variable

    - by Evan Teran
    I have an API which internally has some exceptions for error reporting. The basic structure is that it has a root exception object which inherits from std::exception, then it will throw some subclass of that. Since catching an exception thrown in one library and catching it in another can lead to undefined behavior (at least Qt complains about it and disallows it in many contexts). I would like to wrap the library calls in functions which will return a status code, and if an exception occurred, a copy of the exception object. What is the best way to store an exception (with it's polymorphic behavior) for later use? I believe that the c++0x futures API makes use of something like this. So what is the best approach? The best I can think of is to have a clone() method in each exception class which will return a pointer to an exception of the same type. But that's not very generic and doesn't deal with standard exceptions at all. Any thoughts?

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  • Clickable links in UILabel?

    - by lope
    Hi there, I have been searching for this for hours but I failed. I probably don't even know what should I be looking for. Many applications have text and in this text are web hyperlinks in rounded rect, when I click them UIWebView opens. What puzzles me is that they often have custom links, for example if words starts with # it is also clickable and aplication responds by opening another view. How can I do that? Is it possible with UILabel or do I need UITextView or something else? I really hope it is standard functionality and i don't need to subclass anything :/

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  • How can open source projects obtain license for commercial software without spending a lot of money?

    - by Ikaso
    I just joined an open source project on codeplex. The project is based on the .NET compact framework. So the development tool is Visual Studio. Currently I am using some trial version of Visual Studio which is going to end and I wondered how can I obtain a valid license to work on the project without spending a lot of money. Please pay attention that the Express edition does not help me since my application is running on Windows Mobile 6.5 which is not supported on the Express edition (and the 2010 Express edition supports only Windows Mobile Phone 7 series development). In the general sense, are there some organizations that donate software licenses for open source projects?

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