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  • Why AutoResetEvent and ManualResetEvent does not support name in the constructor?

    - by Ikaso
    On .NET Framework 2.0 AutoResetEvent and ManualResetEvent inherit from EventWaitHandle. The EventWaitHandle class has 4 different constructors. 3 of the constructors support giving a name to the event. On the other hand both ManualResetEvent and AutoResetEvent do not support naming and provide a single constructor that receives the initialState. I can simply inherit from EventWaitHandle and write my own implementation of those classes that support all the constructor overloads, but I don't like to re-invent the wheel if I do not have to. My questions are: Is there a special problem in naming events? Do you have any idea why Microsoft did not support it? Do you have a proposal better than inheriting from the EventWaitHandle class and calling the appropriate constructor as in the following example? public class MyAutoResetEvent: EventWaitHandle { public MyAutoResetEvent(bool initialState) : base(initialState, EventResetMode.AutoReset) { } public MyAutoResetEvent(bool initialState, string name) : base(initialState, EventResetMode.AutoReset, name) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew) : base(initialState, EventResetMode.AutoReset, name, out createdNew) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew, EventWaitHandleSecurity eventSecurity) : base(initialState, EventResetMode.AutoReset, string.Empty, out createdNew, eventSecurity) { } }

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  • Performance of C# method polymorphism with generics

    - by zildjohn01
    I noticed in C#, unlike C++, you can combine virtual and generic methods. For example: using System.Diagnostics; class Base { public virtual void Concrete() {Debug.WriteLine("base concrete");} public virtual void Generic<T>() {Debug.WriteLine("base generic");} } class Derived : Base { public override void Concrete() {Debug.WriteLine("derived concrete");} public override void Generic<T>() {Debug.WriteLine("derived generic");} } class App { static void Main() { Base x = new Derived(); x.Concrete(); x.Generic<PerformanceCounter>(); } } Given that any number of versions of Generic<T> could be instantiated, it doesn't look like the standard vtbl approach could be used to resolve method calls, and in fact it's not. Here's the generated code: x.Concrete(); mov ecx,dword ptr [ebp-8] mov eax,dword ptr [ecx] call dword ptr [eax+38h] x.Generic<PerformanceCounter>(); push 989A38h mov ecx,dword ptr [ebp-8] mov edx,989914h call 76A874F1 mov dword ptr [ebp-4],eax mov ecx,dword ptr [ebp-8] call dword ptr [ebp-4] The extra code appears to be looking up a dynamic vtbl according to the generic parameters, and then calling into it. Has anyone written about the specifics of this implementation? How well does it perform compared to the non-generic case?

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  • Jquery mobile email form with php script

    - by Pablo Marino
    i'm working in a mobile website and i'm having problems with my email form The problem is that when I receive the mail sent through the form, it contains no data. All the data entered by the user is missing. Here is the form code <form action="correo.php" method="post" data-ajax="false"> <div> <p><strong>You can contact us by filling the following form</strong></p> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="first_name">First Name</label> <input id="first_name" placeholder="" type="text" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="last_name">Last name</label> <input id="last_name" placeholder="" type="text" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="email">Email</label> <input id="email" placeholder="" type="email" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="telephone">Phone</label> <input id="telephone" placeholder="" type="tel" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="age">Age</label> <input id="age" placeholder="" type="number" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup" data-mini="true"> <label for="country">Country</label> <input id="country" placeholder="" type="text" /> </fieldset> </div> <div data-role="fieldcontain"> <fieldset data-role="controlgroup"> <label for="message">Your message</label> <textarea id="message" placeholder="" data-mini="true"></textarea> </fieldset> </div> <input data-inline="true" data-theme="e" value="Submit" data-mini="true" type="submit" /> </form> Here is the PHP code <? /* aqui se incializan variables de PHP */ if (phpversion() >= "4.2.0") { if ( ini_get('register_globals') != 1 ) { $supers = array('_REQUEST', '_ENV', '_SERVER', '_POST', '_GET', '_COOKIE', '_SESSION', '_FILES', '_GLOBALS' ); foreach( $supers as $__s) { if ( (isset($$__s) == true) && (is_array( $$__s ) == true) ) extract( $$__s, EXTR_OVERWRITE ); } unset($supers); } } else { if ( ini_get('register_globals') != 1 ) { $supers = array('HTTP_POST_VARS', 'HTTP_GET_VARS', 'HTTP_COOKIE_VARS', 'GLOBALS', 'HTTP_SESSION_VARS', 'HTTP_SERVER_VARS', 'HTTP_ENV_VARS' ); foreach( $supers as $__s) { if ( (isset($$__s) == true) && (is_array( $$__s ) == true) ) extract( $$__s, EXTR_OVERWRITE ); } unset($supers); } } /* DE AQUI EN ADELANTE PUEDES EDITAR EL ARCHIVO */ /* reclama si no se ha rellenado el campo email en el formulario */ /* aquí se especifica la pagina de respuesta en caso de envío exitoso */ $respuesta="index.html#respuesta"; // la respuesta puede ser otro archivo, en incluso estar en otro servidor /* AQUÍ ESPECIFICAS EL CORREO AL CUAL QUEIRES QUE SE ENVÍEN LOS DATOS DEL FORMULARIO, SI QUIERES ENVIAR LOS DATOS A MÁS DE UN CORREO, LOS PUEDES SEPARAR POR COMAS */ $para ="[email protected];" /* this is not my real email, of course */ /* AQUI ESPECIFICAS EL SUJETO (Asunto) DEL EMAIL */ $sujeto = "Mail de la página - Movil"; /* aquí se construye el encabezado del correo, en futuras versiones del script explicaré mejor esta parte */ $encabezado = "From: $first_name $last_name <$email>"; $encabezado .= "\nReply-To: $email"; $encabezado .= "\nX-Mailer: PHP/" . phpversion(); /* con esto se captura la IP del que envío el mensaje */ $ip=$REMOTE_ADDR; /* las siguientes líneas arman el mensaje */ $mensaje .= "NOMBRE: $first_name\n"; $mensaje .= "APELLIDO: $last_name\n"; $mensaje .= "EMAIL: $email\n"; $mensaje .= "TELEFONO: $telephone\n"; $mensaje .= "EDAD: $age\n"; $mensaje .= "PAIS: $country\n"; $mensaje .= "MENSAJE: $message\n"; /* aqui se intenta enviar el correo, si no se tiene éxito se da un mensaje de error */ if(!mail($para, $sujeto, $mensaje, $encabezado)) { echo "<h1>No se pudo enviar el Mensaje</h1>"; exit(); } else { /* aqui redireccionamos a la pagina de respuesta */ echo "<meta HTTP-EQUIV='refresh' content='1;url=$respuesta'>"; } ?> Any help please? Thanks in advance Pablo

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  • Virtual destructors for interfaces.

    - by wowus
    Do interfaces need a virtual destructor, or is the auto-generated one fine? For example, which of the following two code snippets is best, and why? class Base { public: virtual void foo() = 0; virtual ~Base() {} }; OR... class Base { public: virtual void foo() = 0; };

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  • sqlalchemy: what is the difference between declaring the cascade within the foreign key vs relation?

    - by steve
    what is the difference between declaring the cascade within a foreign key vs relations? class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id', onupdate="CASCADE", ondelete="CASCADE"))) vs class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact", cascade="all, delete-orphan") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id')) with the foreign key declaration, it seems like the cascade is enforced at the database level. how does the relations approach work? thanks!

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  • c# - what approach can I use to extend a group of classes that include implemented methods? (see des

    - by Greg
    Hi, I want to create an extendible package I am writing that has Topology, Node & Relationship classes. The idea is these base classes would have the various methods in them necessary to base graph traversal methods etc. I would then like to be able to reuse this by extending the package. For example the base requirements might see Relationship with a parentNode & childNode. Topology would have a List of Nodes and List of Relationships. Topology would have methods like FindChildren(int depth). Then the usage would be to extend these such that additional attributes for Node and Relationships could be added etc. QUESTION - What would be the best approach to package & expose the base level classes/methods? (it's kind of like a custom collection but with multiple facets). Would the following concepts come into play: Interfaces - would this be a good idea to have ITopology, INode etc, or is this not required as the user would extend these classes anyway? Abstract Classes - would the base classes be abstract classes Custom Generic Collection - would some approach using this concept assist (but how would this work if there are the 3 different classes) thanks

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  • unable to install latest phpUnit in Ubuntu 10.04

    - by Dex Barrett
    I'm trying to install PHPUnit in Ubuntu 10.04 but I get these error messages sudo pear install -a pear.phpunit.de/PHPUnit Duplicate package channel://pear.phpunit.de/File_Iterator-1.3.3 found Duplicate package channel://pear.phpunit.de/File_Iterator-1.3.2 found install failed I tried reinstalling PEAR, upgrading it; updated the PEAR and PHPUnit channel; cleared the PEAR's cache but still no luck, I keep getting the same error. Does anyone have the same problem and know how to solve it? Thank you.

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  • Finding What You Need in R: function arguments/parameters from outside the function's package

    - by doug
    Often in R, there are a dozen functions scattered across as many packages--all of which have the same purpose but of course differ in accuracy, performance, theoretical rigor, and so on. How do you gather all of these in one place before you start your task? So for instance: the generic plot function. Setting secondary ticks is much easier (IMHO) using a function outside of the base package, minor.tick(nx=n, ny=n, tick.ratio=n), found in Hmisc. Of course, that doesn't show up in plot's docstring. Likewise, the data-input arguments to 'plot' can be supplied by an object returned from the function 'hexbin', again, from a library outside of the base installation (where 'plot' resides). What would be great obviously is a programmatic way to gather these function arguments from the various libraries and put them in a single namespace. edit: (trying to re-state my example just above more clearly:) the arguments to plot supplied in the base package for, e.g., setting the axis tick frequency are xaxp/yaxp; however, one can also set a/t/f via a function outside of the base package, again, as in the minor.tick function from the Hmisc package--but you wouldn't know that just from looking at the plot method signature. Is there a meta function in R for this? So far, as i come across them, i've been manually gathering them in a TextMate 'snippet' (along with the attendant library imports). This isn't that difficult or time consuming, but i can only update my snippet as i find out about these additional arguments/parameters. Is there a canonical R way to do this, or at least an easier way? Just in case that wasn't clear, i am not talking about the case where multiple packages provide functions directed to the same statistic or view (e.g., 'boxplot' in the base package; 'boxplot.matrix' in gplots; and 'bplots' in Rlab). What i am talking is the case in which the function name is the same across two or more packages.

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  • google maps api keys to be set webserver-wide, (as env var? inside apache?)

    - by ~knb
    I have a web site with many virtual hosts and each registered with several domain names (ending in .org, .de), site1.mysite.de, site2.mysite.org Then I have different templating systems based on several programming languages (perl and php) in use on the web server. The Google Maps Api requires a unique Google Maps api key for each vhost. I want to have something like a web-server wide variable $goomapkey that I can call from inside my code. In PHP code, Now I have a kludgy case-analysis solution like $domain = substr($_SERVER['SERVER_NAME'], -3); if (".de" == $domain){ //if ("xxxxxx" eq substr($ENV{SERVER_NAME}, 0, 5)){ // $gookey = "ABQIAAA..."; //} else { //site1.de $gookey = "ABQIAAAA1Js..."; //} } elseif ("dev" == substr($_SERVER['SERVER_NAME'], 0, 3)){ //dev.mysite.org $gookey = "ABQIAAAA1JsSb..."; } else { //www.mysite.org $gookey = "ABQIAAAA1JsS..."; //TODO: Add more keys for each virtual host, for my.machinename.de, IP-address based URL, ... } ... inside my php-based CMS. A non-ideal solution, because it is, php-only, and I still have to set it at several html templates inside the CMS, and there are too many cases. I want the google maps api key to be set by the apache web server who examines the request *early in the request loop before any php page template code is constructed and evaluated. is an environment variable a good solution? which technology should be used to set the $goomapkey variable? I'd prefer mod_perl2 Apache request handler, but the documentation is confusing (many API changes in the past ). Which Apache module could I use? Is there a built-in Apache module that does the same thing?

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  • (this == null) in C#!

    - by SLaks
    Due to a bug that was fixed in C# 4, the following program prints true. (Try it in LINQPad) void Main() { new Derived(); } class Base { public Base(Func<string> valueMaker) { Console.WriteLine(valueMaker()); } } class Derived : Base { string CheckNull() { return "Am I null? " + (this == null); } public Derived() : base(() => CheckNull()) { } } In VS2008 in Release mode, in throws an InvalidProgramException. (In Debug mode, it works fine) In VS2010 Beta 2, it doesn't compile (I didn't try Beta 1); I learned that the hard way Is there any other way to make this == null in pure C#?

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  • Rails: url_for to be available in a isolated class that must be instanced

    - by Totty
    Rails: url_for to be available in a isolated class that must be instanced: class ProfilePresenter < ActionController::Base attr_reader :profile def initialize(profile) super @a = url_for(:controller => 'profiles', :action => 'view', :profile_url => 'dd') @a @profile = profile end end How to make the url_for work? i tried to extend the ActionController::Base and the ActionView::Base and i cant :s

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  • Behavior of virtual function in C++

    - by Summer_More_More_Tea
    Hi everyone: I have a question, here are two class below: class Base{ public: virtual void toString(); // generic implementation } class Derive : public Base{ public: ( virtual ) void toString(); // specific implementation } The question is: If I wanna subclass of class Derive perform polymophism using a pointer of type Base, is keyword virtual in the bracket necessary? If the answer is no, what's the difference between member function toString of class Derive with and without virtual?

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  • 1 bug to kill... Letting PHP Generate The Canonical.

    - by Sam
    Hi folks, for building a clean canonical url, that always returns 1 base URL, im stuck in following case: <?php # every page $extensions = $_SERVER['REQUEST_URI']; # path like: /en/home.ast?ln=ja $qsIndex = strpos($extensions, '?'); # removes the ?ln=de part $pageclean = $qsIndex !== FALSE ? substr($extensions, 0, $qsIndex) : $extensions; $canonical = "http://website.com" . $pageclean; # basic canonical url ?> <html><head><link rel="canonical" href="<?=$canonical?>"></head> when URL : http://website.com/de/home.ext?ln=de canonical: http://website.com/de/home.ext BUT I want to remove the file extension aswell, whether its .php, .ext .inc or whatever two or three char extension .[xx] or .[xxx] so the base url becomes: http://website.com/en/home Aaah much nicer! but How do i achieve that in current code? Any hints are much appreciated +! (other advices for proper canonical usage in this multi-lingual environment are welcome as well)

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  • make VIEW of SHOW TABLE query

    - by cneeds
    Is there a way to make a VIEW of this SHOW TABLE query? SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table" When I save this as a view (using phpMyAdmin) I get #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table"' at line 4 when phpMyAdmin tries to execute this CREATE ALGORITHM = UNDEFINED VIEW `Tables` AS SHOW FULL TABLES FROM `db_name` WHERE `Table_type` = "Base table"

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  • Whats wrong with the following code, its not compiling

    - by Ganesh Kundapur
    #include <iostream> #include <vector> using namespace std; class Base { public: void Display( void ) { cout<<"Base display"<<endl; } int Display( int a ) { cout<<"Base int display"<<endl; return 0; } }; class Derived : public Base { public: void Display( void ) { cout<<"Derived display"<<endl; } }; void main() { Derived obj; obj.Display(); obj.Display( 10 ); } $test1.cpp: In function ‘int main()’: test1.cpp:35: error: no matching function for call to ‘Derived::Display(int)’ test1.cpp:24: note: candidates are: void Derived::Display() On commenting obj.Display(10), it works.

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  • Inheritance - initialization problem

    - by dumbquestion
    I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

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  • How do I execute queries upon DB connection in Rails?

    - by sycobuny
    I have certain initializing functions that I use to set up audit logging on the DB server side (ie, not rails) in PostgreSQL. At least one has to be issued (setting the current user) before inserting data into or updating any of the audited tables, or else the whole query will fail spectacularly. I can easily call these every time before running any save operation in the code, but DRY makes me think I should have the code repeated in as few places as possible, particularly since this diverges greatly from the ideal of database agnosticism. Currently I'm attempting to override ActiveRecord::Base.establish_connection in an initializer to set it up so that the queries are run as soon as I connect automatically, but it doesn't behave as I expect it to. Here is the code in the initializer: class ActiveRecord::Base # extend the class methods, not the instance methods class << self alias :old_establish_connection :establish_connection # hide the default def establish_connection(*args) ret = old_establish_connection(*args) # call the default # set up necessary session variables for audit logging # call these after calling default, to make sure conn is established 1st db = self.class.connection db.execute("SELECT SV.set('current_user', 'test@localhost')") db.execute("SELECT SV.set('audit_notes', NULL)") # end "empty variable" err ret # return the default's original value end end end puts "Loaded custom establish_connection into ActiveRecord::Base" sycobuny:~/rails$ ruby script/server = Booting WEBrick = Rails 2.3.5 application starting on http://0.0.0.0:3000 Loaded custom establish_connection into ActiveRecord::Base This doesn't give me any errors, and unfortunately I can't check what the method looks like internally (I was using ActiveRecord::Base.method(:establish_connection), but apparently that creates a new Method object each time it's called, which is seemingly worthless cause I can't check object_id for any worthwhile information and I also can't reverse the compilation). However, the code never seems to get called, because any attempt to run a save or an update on a database object fails as I predicted earlier. If this isn't a proper way to execute code immediately on connection to the database, then what is?

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  • Getting a type for a template instantiation?

    - by ebo
    I have the following situation: I have a object of type MyClass, which has a method to cast itself to it's base class. The class includes a typedef for it's base class and a method to do the downcast. template <class T, class B> class BaseClass; template <class T> class NoAccess; template <class T> class MyClass : public BaseClass<T, NoAccess<T> > { private: typedef BaseClass<T, NoAccess<T> > base; public: base &to_base(); }; I need to pass the result of a base call to a functor Operator: template <class Y> class Operator { Operator(Y &x); }; Operator<???> op(myobject.to_base()); Is there a easy way to fill the ??? provided that I do not want to use NoAccess?

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  • Figuring out what makes a C++ class abstract in VS2008

    - by suszterpatt
    I'm using VS2008 to build a plain old C++ program (not C++/CLI). I have an abstract base class and a non-abstract derived class, and building this: Base* obj; obj = new Derived(); fails with the error "'Derived': cannot instantiate abstract class". (It may be worth noting, however, that if I hover over Base with the cursor, VS will pop up a tooltip saying "class Base abstract", but hovering over Derived will only say "class Derived" (no "abstract")). The definitions of these classes are fairly large and I'd like to avoid manually checking if each method has been overridden. Can VS do this for me somehow? Any general tips on pinpointing the exact parts of the class' definition that make it abstract?

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  • Why doesn't C++ allow you to request a pointer to the most derived class?

    - by Matthew Lowe
    (This question should probably be answered with a reference to Stroustrup.) It seems extremely useful to be able to request a pointer to the most derived class, as in the following: class Base { ... }; class DerivedA { ... }; class DerivedB { ... }; class Processor { public: void Do(Base* b) {...} void Do(DerivedA* d) {...} void Do(DerivedB* d) {...} }; list<Base*> things; Processor p; for(list<Base*>::iterator i=things.begin(), e=things.end(); i!=e; ++i) { p.Do(CAST_TO_MOST_DERIVED_CLASS(*i)); } But this mechanism isn't provided in c++. Why?

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  • Rails 3 HABTM Strange Association: Project and Employee in a tree.

    - by Mauricio
    Hi guys I have to adapt an existing model to a new relation. I have this: A Project has many Employees. the Employees of a Project are organized in some kind of hierarchy (nothing fancy, I resolved this adding a parent_id for each employee to build the 'tree') class Employee < AR:Base belongs_to :project belongs_to :parent, :class_name => 'Employee' has_many :childs, :class_name => 'Employee', :foreign_column => 'parent_id' end class Project < AR:Base has_many :employees, end That worked like a charm, now the new requirement is: The Employees can belong to many Projects at the same time, and the hierarchy will be different according to the project. So I though I will need a new table to build the HABTM, and a new class to access the parent_id to build the tree. Something like class ProjectEmployee < AR:Base belongs_to :project belongs_to :employee belongs_to :parent, :class_name => 'Employee' # <--- ?????? end class Project < AR:Base has_many :project_employee has_many :employees, :through => :project_employee end class Employee < AR:Base has_many :project_employee has_many :projects, :through => :project_employee end How can I access the parent and the childs of an employee for a given project? I need to add and remove childs as wish from the employees of a project. Thank you!

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  • multiple models in Rails with a shared interface

    - by dfondente
    I'm not sure of the best structure for a particular situation in Rails. We have several types of workshops. The administration of the workshops is the same regardless of workshop type, so the data for the workshops is in a single model. We collect feedback from participants about the workshops, and the questionnaire is different for each type of workshop. I want to access the feedback about the workshop from the workshop model, but the class of the associated model will depend on the type of workshop. If I was doing this in something other than Rails, I would set up an abstract class for WorkshopFeedback, and then have subclasses for each type of workshop: WorkshopFeedbackOne, WorkshopFeedbackTwo, WorkshopFeedbackThree. I'm unsure how to best handle this with Rails. I currently have: class Workshop < ActiveRecord::Base has_many :workshop_feedbacks end class Feedback < ActiveRecord::Base belongs_to :workshop has_many :feedback_ones has_many :feedback_twos has_many :feedback_threes end class FeedbackOne < ActiveRecord::Base belongs_to :feedback end class FeedbackTwo < ActiveRecord::Base belongs_to :feedback end class FeedbackThree < ActiveRecord::Base belongs_to :feedback end This doesn't seem like to the cleanest way to access the feedback from the workshop model, as accessing the correct feedback will require logic investigating the Workshop type and then choosing, for instance, @workshop.feedback.feedback_one. Is there a better way to handle this situation? Would it be better to use a polymorphic association for feedback? Or maybe using a Module or Mixin for the shared Feedback interface? Note: I am avoiding using Single Table Inheritance here because the FeedbackOne, FeedbackTwo, FeedbackThree models do not share much common data, so I would end up with a large sparsely populated table with STI.

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  • How to implement a private virtual function within derived classes?

    - by Dane
    Hi, I know why I want to use private virtual functions, but how exactly can I implement them? For example: class Base{ [...] private: virtual void func() = 0; [...] } class Derived1: puplic Base{ void func() { //short implementation is ok here } } class Derived2: puplic Base{ void func(); //long implementation elsewhere (in cpp file) } [...] void Derived2::func() { //long implementation } The first version is ok but not always possible. Isn't the second version simply name hiding? How do you define the Base::func() of Derived2, if you cannot do it within the class declaration of Dereived2? Thanks

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  • Retrieve value of one column in a table

    - by user327094
    Here is my problem: I have 2 tables Accounts and Transaction Logs. in Accounts table, it has column "Amount" which is a base amount of an account. and in Trans Logs table, it also has column "Amount" which is additional (add or minus to the base amount) amount of the account. and I don't know how to retrieve that base amount to edit it, then save it back to the table. That means I need to get a value of the right column by using Acc_No to find. I'm using DataSet, by the way. i think it should go like this: Dim Amount as Decimal Amount = *the code to retrieve the base amount* Amount = Amount + txtAmount.Text *the code to save the new amount back to Accounts table* Thank you!

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