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• In SQL, we can use "Union" to merge two tables. What are different ways to do "Intersection"?

  - by Jian Lin

  In SQL, there is an operator to "Union" two tables. In an interview, I was told that, say one table has just 1 field with 1, 2, 7, 8 in it, and another table also has just 1 field with 2, and 7 in it, how do I get the intersection. I was stunned at first, because I never saw it that way. Later on, I found that it is actually a "Join" (inner join), which is just select * from t1, t2 where t1.number = t2.number (although the name "join" feels more like "union" rather than "intersect") another solution seems to be select * from t1 INTERSECT select * from t2 but it is not supported in MySQL. Are there different ways to get the intersection besides these two methods?

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• How to handle Application_BeginRequest using a custom filter in asp.net mvc?

  - by denis_n

  How to handle Application_BeginRequest using a custom filter in asp.net mvc? I want to restore session only for one route (~/my-url). I would be cool, if I could create a custom filter and handle that. protected void Application_BeginRequest(object sender, EventArgs e) { var context = HttpContext.Current; if (string.Equals("~/my-url", context.Request.AppRelativeCurrentExecutionFilePath, StringComparison.OrdinalIgnoreCase)) { string sessionId = context.Request.Form["sessionId"]; if (sessionId != null) { HttpCookie cookie = context.Request.Cookies.Get("ASP.NET_SessionId"); if (cookie == null) { cookie = new HttpCookie("ASP.NET_SessionId"); } cookie.Value = sessionId; context.Request.Cookies.Set(cookie); } }

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• Matching of tuples

  - by Jack

  From what I understood I can use pattern-matching in a match ... with expression with tuples of values, so something like match b with ("<", val) -> if v < val then true else false | ("<=", val) -> if v <= val then true else false should be correct but it gives me a syntax error as if the parenthesis couldn't be used: File "ocaml.ml", line 41, characters 14-17: Error: Syntax error: ')' expected File "ocaml.ml", line 41, characters 8-9: Error: This '(' might be unmatched referring on first match clause.. Apart from that, can I avoid matching strings and applying comparisons using a sort of eval of the string? Or using directly the comparison operator as the first element of the tuple?

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• Prolog for beginners about logic and syntax

  - by lnotik

  Hello everybody. I have this question : I need to create a paradict "rightGuesses" which will get 3 arguments , each one of them is a list of letters : 1) The list of guessed letters 2) The word i have to guess 3) The letters that where guessed so far . for example : rightGuesses([n,o,p,q], [p,r,o,l,o,g], Ans). will give us Ans = [p, -, o, -, o, -]. i made: rightGuesses([],T2,[ANS]) rightGuesses([A|T1],T2,[ANS]):- (member(A,T2))=\=true , rightGuesses(T1,T2,[ _ |'-']). rightGuesses([A|T1],T2,[ANS]):- member(A,T2), rightGuesses(T1,T2,[ _ |A]). but i get : ERROR: c:/users/leonid/desktop/file3.pl:5:0: Syntax error: Operator expected Warning: c:/users/leonid/desktop/file3.pl:6: when i trying to compile it what is my problem , and is there is a better way to do it ? thanks in advance.

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• Dynamically set generic type argument

  - by fearofawhackplanet

  Following on from my question here, I'm trying to create a generic value equality comparer. I've never played with reflection before so not sure if I'm on the right track, but anyway I've got this idea so far: bool ContainSameValues<T>(T t1, T t2) { if (t1 is ValueType || t1 is string) { return t1.Equals(t2); } else { IEnumerable<PropertyInfo> properties = t1.GetType().GetProperties().Where(p => p.CanRead); foreach (var property in properties) { var p1 = property.GetValue(t1, null); var p2 = property.GetValue(t2, null); if( !ContainSameValues<p1.GetType()>(p1, p2) ) return false; } } return true; } This doesn't compile because I can't work out how to set the type of T in the recursive call. Is it possible to do this dynamically at all? There are a couple of related questions on here which I have read but I couldn't follow them enough to work out how they might apply in my situation.

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• java.io in debian

  - by Stig

  Hello, i try to compile a java program but in the import section of the code fails: import java.net.; import java.io.; import java.util.; import java.text.; import java.awt.; //import java.awt.image.; import java.awt.event.; //import java.awt.image.renderable.; import javax.swing.; import javax.swing.border.; //import javax.swing.border.EtchedBorder; //import javax.media.jai.; //import javax.media.jai.operator.; //import com.sun.media.jai.codec.; //import java.lang.reflect.; how can i fix the problem in a linux debian machine?. Thanks

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• Put logic behind generated LinqToSql fields

  - by boris callens

  In a database I use throughout several projects, there is a field that should actually be a boolean but is for reasons nobody can explain to me a field duplicated over two tables where one time it is a char ('Y'/'N') and one time an int (1/0). When I generate a datacontext with LinqToSql the fields off course gets these datatypes. It would be nice if I don't have to drag this stupid choice of datatype throughout the rest of my application. Is there a way to give the generated classes a little bit of logic that just return me return this.equals('Y'); and return this==1; Preferably without having to make an EXTRA field in my partial class. It would be a solution to give the generated field a totally different name that can only be accessed through the partial class and then generate the extra field with the original name with my custom logic in the partial class. I don't know how to alter the accesibility level in my generated class though.. Any suggestions?

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• Decorator for determining HTTP response from a view

  - by polera

  I want to create a decorator that will allow me to return a raw or "string" representation of a view if a GET parameter "raw" equals "1". The concept works, but I'm stuck on how to pass context to my renderer. Here's what I have so far: from django.shortcuts import render_to_response from django.http import HttpResponse from django.template.loader import render_to_string def raw_response(template): def wrap(view): def response(request,*args,**kwargs): if request.method == "GET": try: if request.GET['raw'] == "1": render = HttpResponse(render_to_string(template,{}),content_type="text/plain") return render except Exception: render = render_to_response(template,{}) return render return response return wrap Currently, the {} is there just as a place holder. Ultimately, I'd like to be able to pass a dict like this: @raw_response('my_template_name.html') def view_name(request): render({"x":42}) Any assistance is appreciated.

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• C# : Number Conversion Problem

  - by Sayem Ahmed

  Today I faced a strange problem in C#. I have an ASP.NET page where user can enter certain price, quantity etc. I get the price value, convert it to double, then multiply it with 100 and then typecast it to an integer. When the price is "33.30", after converting it to double it remains 33.3 (obviously...), but after multiplying it with 100, it becomes 3329.9999999999995, and when I cast it to integer by applying simple cast operator "(int) (price * 100) ", it becomes 3329. Right now I have no idea why this is happening. So I thought may be you guys can help :) .

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• Sort CMap Key by String Length

  - by Yan Cheng CHEOK

  Previously, I am using STL map to perform the mentioned task. struct ltstr { bool operator()(std::string s1, std::string s2) const { const int l1 = s1.length(); const int l2 = s2.length(); if (l1 == l2) { // In alphabetical order. return s1.compare(s2) < 0; } // From longest length to shortest length. return l1 > l2; } }; std::map<std::string, int, ltstr> m; How can I perform the same task using CMap? // How to make key sorted by string length? CMap<CString, LPCTSTR, int, int> m;

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• When using Query Syntax in C# "Enumeration yielded no results". How to retrieve output

  - by Shantanu Gupta

  I have created this query to fetch some result from database. Here is my table structure. What exaclty is happening. DtMapGuestDepartment as Table 1 DtDepartment as Table 2 Are being used var dept_list= from map in DtMapGuestDepartment.AsEnumerable() where map.Field<Nullable<long>>("GUEST_ID") == DRowGuestPI.Field<Nullable<long>>("PK_GUEST_ID") join dept in DtDepartment.AsEnumerable() on map.Field<Nullable<long>>("DEPARTMENT_ID") equals dept.Field<Nullable<long>>("DEPARTMENT_ID") select dept.Field<string>("DEPARTMENT_ID"); I am performing this query on DataTables and expect it to return me a datatable. Here I want to select distinct department from Table 1 as well which will be my next quest. Please answer to that also if possible.

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• SoundPool.load() and FileDescriptor from file

  - by Hans

  I tried using the load function of the SoundPool that takes a FileDescriptor, because I wanted to be able to set the offset and length. The File is not stored in the Ressources but a file on the storage card. Even though neither the load nor the play function of the SoundPool throw any Exception or print anything to the console, the sound is not played. Using the same code, but use the file path string in the SoundPool constructor works perfectly. This is how I have tried the loading (start equals 0 and length is the length of the file in miliseconds): FileInputStream fileIS = new FileInputStream(new File(mFile)); mStreamID = mSoundPool.load(fileIS.getFD(), start, length, 0); mPlayingStreamID = mSoundPool.play(mStreamID, 1f, 1f, 1, 0, 1f); If I would use this, it works: mStreamID = mSoundPool.load(mFile, 0); mPlayingStreamID = mSoundPool.play(mStreamID, 1f, 1f, 1, 0, 1f); Any ideas anyone? Thanks

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• Showing ImageView next to TextView in a ListView

  - by KDEx

  So I have a listview that is displaying correctly. When the item is "turned on" the text is white and when it's turned off it's grey. That part all functions great. However when I add the ImageView into the mix I get a null pointer exception. I don't understand why. I've tried using bitmaps as well and get the same problem. Here is some code: @Override public void bindView(View view, Context context, Cursor cursor) { TextView rRule = (TextView) view.findViewById(R.id.rule_text); TextView rType = (TextView) view.findViewById(R.id.rule_type); ImageView iChecked = (ImageView) view.findViewById(R.id.checkBox); String ruleName = cursor.getString(1); int ruleType = cursor.getInt(2); String ruleEnabled = cursor.getString(3); switch (ruleType) { /*...some irrelevant code */ } if (ruleEnabled.equals("true")) { rRule.setTypeface(null, Typeface.BOLD); rRule.setTextColor(Color.WHITE); iChecked.setVisibility(View.VISIBLE); //line 271 } else if (ruleEnabled.equals("false")) { rRule.setTypeface(null, Typeface.NORMAL); rRule.setTextColor(Color.GRAY); iChecked.setVisibility(View.GONE); } rRule.setText(ruleName); } Per request the error log: (Sorry was under the impression null pointers dont say anything helpful..I know the error is the imageview) 06-29 10:29:02.777: E/AndroidRuntime(29516): FATAL EXCEPTION: main 06-29 10:29:02.777: E/AndroidRuntime(29516): java.lang.NullPointerException 06-29 10:29:02.777: E/AndroidRuntime(29516): at com.company.app.DefaultRulesList$RulesAdapter.bindView(DefaultRulesList.java:271) 06-29 10:29:02.777: E/AndroidRuntime(29516): at com.company.app.DefaultRulesList$RulesAdapter.newView(DefaultRulesList.java:284) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.CursorAdapter.getView(CursorAdapter.java:246) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.AbsListView.obtainView(AbsListView.java:2033) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.ListView.makeAndAddView(ListView.java:1772) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.ListView.fillDown(ListView.java:672) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.ListView.fillFromTop(ListView.java:732) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.ListView.layoutChildren(ListView.java:1625) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.AbsListView.onLayout(AbsListView.java:1863) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.View.layout(View.java:11278) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewGroup.layout(ViewGroup.java:4224) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1628) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1486) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.onLayout(LinearLayout.java:1399) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.View.layout(View.java:11278) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewGroup.layout(ViewGroup.java:4224) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.FrameLayout.onLayout(FrameLayout.java:431) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.View.layout(View.java:11278) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewGroup.layout(ViewGroup.java:4224) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1628) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1486) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.LinearLayout.onLayout(LinearLayout.java:1399) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.View.layout(View.java:11278) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewGroup.layout(ViewGroup.java:4224) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.widget.FrameLayout.onLayout(FrameLayout.java:431) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.View.layout(View.java:11278) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewGroup.layout(ViewGroup.java:4224) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1489) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.os.Handler.dispatchMessage(Handler.java:99) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.os.Looper.loop(Looper.java:137) 06-29 10:29:02.777: E/AndroidRuntime(29516): at android.app.ActivityThread.main(ActivityThread.java:4424) 06-29 10:29:02.777: E/AndroidRuntime(29516): at java.lang.reflect.Method.invokeNative(Native Method) 06-29 10:29:02.777: E/AndroidRuntime(29516): at java.lang.reflect.Method.invoke(Method.java:511) 06-29 10:29:02.777: E/AndroidRuntime(29516): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 06-29 10:29:02.777: E/AndroidRuntime(29516): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 06-29 10:29:02.777: E/AndroidRuntime(29516): at dalvik.system.NativeStart.main(Native Method) Code for iChecked (where the id is called) <ImageView android:id="@+id/checkBox" android:padding="2dip" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@android:drawable/checkbox_on_background"/>

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• visual studio intellisense error

  - by rakkarage

  template <typename T> class Test { friend Test<T> & operator * (T lhs, const Test<T> & rhs) { Test<T> r(rhs); // return r *= lhs; } } 4 IntelliSense: identifier "T" is undefined why is T defined on line 3 but not line 4? i mean i guess its not a real error just an intellisense error... it works anyway but is there something wrong? can i fix it? or remove the red squiggles somehow? thanks i am using visual studio 2010... i wonder if this happens in other versions as well?

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• Boost::Container::Vector with Enum Template Argument - Not Legal Base Class

  - by CuppM

  Hi, I'm using Visual Studio 2008 with the Boost v1.42.0 library. If I use an enum as the template argument, I get a compile error when adding a value using push_back(). The compiler error is: 'T': is not a legal base class and the location of the error is move.hpp line 79. #include <boost/interprocess/containers/vector.hpp> class Test { public: enum Types { Unknown = 0, First = 1, Second = 2, Third = 3 }; typedef boost::container::vector<Types> TypesVector; }; int main() { Test::TypesVector o; o.push_back(Test::First); return 0; } If I use a std::vector instead it works. And if I resize the Boost version first and then set the values using the [] operator it also works. Is there some way to make this work using push_back()?

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• Is this call to a function object inlined?

  - by dehmann

  In the following code, Foo::add calls a function via a function object: struct Plus { inline int operator()(int x, int y) const { return x + y; } }; template<class Fct> struct Foo { Fct fct; Foo(Fct f) : fct(f) {} inline int add(int x, int y) { return fct(x,y); // same efficiency adding directly? } }; Is this the same efficiency as calling x+y directly in Foo::add? In other words, does the compiler typically directly replace fct(x,y) with the actual call, inlining the code, when compiling with optimizations enabled?

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• When does ref($variable) return 'IO'?

  - by Zaid

  Here's the relevant excerpt from the documentation of the ref function: The value returned depends on the type of thing the reference is a reference to. Builtin types include: SCALAR ARRAY HASH CODE REF GLOB LVALUE FORMAT IO VSTRING Regexp Based on this, I imagined that calling ref on a filehandle would return 'IO'. Surprisingly, it doesn't: use strict; use warnings; open my $fileHandle, '<', 'aValidFile'; close $fileHandle; print ref $fileHandle; # prints 'GLOB', not 'IO' perlref tries to explain why: It isn't possible to create a true reference to an IO handle (filehandle or dirhandle) using the backslash operator. The most you can get is a reference to a typeglob, which is actually a complete symbol table entry [...] However, you can still use type globs and globrefs as though they were IO handles. In what circumstances would ref return 'IO' then?

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• How to find duplicate values in SQL Server

  - by hgulyan

  Hi, I'm using SQL Server 2008. I have a table Customers customer_number int field1 varchar field2 varchar field3 varchar field4 varchar ... and a lot more columns, that doesn't matter for my queries. Column *customer_number* is pk. I'm trying to find duplicate values and some differences between them. Please, help me to find all rows that have same 1) field1, field2, field3, field4 2) only 3 columns are equal and one of them isn't (except rows from list 1) 3) only 2 columns equal and two of them aren't (except rows from list 1 and list 2) In the end, I'll have 3 tables with this results and additional groupId, which will be same for a group of similars (For example, for 3 column equals, rows that have 3 same columns equal will be a seperate group) Thank you.

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• Appending an element to a collection using LINQ

  - by SRKX

  I am trying to process some list with a functional approach in C#. The idea is that I have a collection of Tuple<T,double> and I want to change the Item 2 of some element T. The functional way to do so, as data is immutable, is to take the list, filter for all elements where the element is different from the one to change, and the append a new tuple with the new values. My problem is that I do not know how to append the element at the end. I would like to do: public List<Tuple<T,double>> Replace(List<Tuple<T,double>> collection, T term,double value) { return collection.Where(x=>!x.Item1.Equals(term)).Append(Tuple.Create(term,value)); } But there is no Append method. Is there something else?

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

  - by user1889765

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

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• Collections not read from hibernate/ehcache second-level-cache

  - by Mark van Venrooij

  I'm trying to cache lazy loaded collections with ehcache/hibernate in a Spring project. When I execute a session.get(Parent.class, 123) and browse through the children multiple times a query is executed every time to fetch the children. The parent is only queried the first time and then resolved from the cache. Probably I'm missing something, but I can't find the solution. Please see the relevant code below. I'm using Spring (3.2.4.RELEASE) Hibernate(4.2.1.Final) and ehcache(2.6.6) The parent class: @Entity @Table(name = "PARENT") @Cacheable @Cache(usage = CacheConcurrencyStrategy.READ_WRITE, include = "all") public class ServiceSubscriptionGroup implements Serializable { /** The Id. */ @Id @Column(name = "ID") private int id; @OneToMany(fetch = FetchType.LAZY, mappedBy = "parent") @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) private List<Child> children; public List<Child> getChildren() { return children; } public void setChildren(List<Child> children) { this.children = children; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Parent that = (Parent) o; if (id != that.id) return false; return true; } @Override public int hashCode() { return id; } } The child class: @Entity @Table(name = "CHILD") @Cacheable @Cache(usage = CacheConcurrencyStrategy.READ_WRITE, include = "all") public class Child { @Id @Column(name = "ID") private int id; @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL) @JoinColumn(name = "PARENT_ID") @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) private Parent parent; public int getId() { return id; } public void setId(final int id) { this.id = id; } private Parent getParent(){ return parent; } private void setParent(Parent parent) { this.parent = parent; } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } final Child that = (Child) o; return id == that.id; } @Override public int hashCode() { return id; } } The application context: <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="annotatedClasses"> <list> <value>Parent</value> <value>Child</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.SQLServer2008Dialect</prop> <prop key="hibernate.hbm2ddl.auto">validate</prop> <prop key="hibernate.ejb.naming_strategy">org.hibernate.cfg.ImprovedNamingStrategy</prop> <prop key="hibernate.connection.charSet">UTF-8</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.use_sql_comments">true</prop> <!-- cache settings ehcache--> <prop key="hibernate.cache.use_second_level_cache">true</prop> <prop key="hibernate.cache.use_query_cache">true</prop> <prop key="hibernate.cache.region.factory_class"> org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory</prop> <prop key="hibernate.generate_statistics">true</prop> <prop key="hibernate.cache.use_structured_entries">true</prop> <prop key="hibernate.cache.use_query_cache">true</prop> <prop key="hibernate.transaction.factory_class"> org.hibernate.engine.transaction.internal.jta.JtaTransactionFactory</prop> <prop key="hibernate.transaction.jta.platform"> org.hibernate.service.jta.platform.internal.JBossStandAloneJtaPlatform</prop> </props> </property> </bean> The testcase I'm running: @Test public void testGetParentFromCache() { for (int i = 0; i <3 ; i++ ) { getEntity(); } } private void getEntity() { Session sess = sessionFactory.openSession() sess.setCacheMode(CacheMode.NORMAL); Transaction t = sess.beginTransaction(); Parent p = (Parent) s.get(Parent.class, 123); Assert.assertNotNull(p); Assert.assertNotNull(p.getChildren().size()); t.commit(); sess.flush(); sess.clear(); sess.close(); } In the logging I can see that the first time 2 queries are executed getting the parent and getting the children. Furthermore the logging shows that the child entities as well as the collection are stored in the 2nd level cache. However when reading the collection a query is executed to fetch the children on second and third attempt.

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• is this a simple monad example?

  - by zcaudate

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

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• Problem of using cin twice.

  - by gc

  Here is the code: string str; cinstr; cout<<"first input:"<<str<<endl; getline(cin, str); cout<<"line input:"<<str<<endl; The result is that getline never pauses for user input, therefore the second output is always empty. After spending some time on it, I realized after the first call "cinstr", it seems '\n' is still stored in cin (using cin.peek() to check), which ends getline immediately. The solution will be adding one more line between the first usage and the second one: cin.ignore(numeric_limits::max(), '\n'); However, I still don't understand, why is '\n' left there after the first call? What does istream& operator really do?

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• passing values to pages

  - by Indranil Mutsuddy

  Hello friends, What i am trying here is to pass values to other pages. When i include the following code private void Button1_Click(object sender, System.EventArgs e) { // Value sent using HttpResponse Response.Redirect("WebForm5.aspx?Name="+txtName.Text); } if (Request.QueryString["Name"]!= null) Response.write( Request.QueryString["Name"]); everything works fine the name gets displayed. Now if use MemberId instead, though i can see the Id in the Url, but while checking for Null in other page, its true. Whats wrong?? Now I tried the same thing using session i.e. Session["MemberId"] = this.TxtEnterMemberId.Text; if (MemberSex.Equals("M")) Response.Redirect("PatientDetailsMale.aspx",false ); Page_load event of the other page if (Session["MemberId"] != null) mid = Session["MemberId"].ToString(); IT Works..Could u guys explain the behaviour please? P.S. Can anyone give a breif in layman words about SessionId and its usage. Thanking you, Indranil

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• Is there alternative way to write this query?

  - by Kugel

  I have tables A, B, C, where A represents items which can have zero or more sub-items stored in C. B table only has 2 foreign keys to connect A and C. I have this sql query: select * from A where not exists (select * from B natural join C where B.id = A.id and C.value > 10); Which says: "Give me every item from table A where all sub-items have value less than 10. Is there a way to optimize this? And is there a way to write this not using exists operator?

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