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  • SQL Query with computed column

    - by plotnick
    help me please with a query. Assume that we have a table with columns: Transaction StartTime EndTime Now, I need a query with computed column of (value = EndTime-Startime). Actually I need to group Users(Transaction has a FK for Users) and sort them by average time spent for transaction.

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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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  • Help naming a class that has a single public method called Execute()

    - by devoured elysium
    I have designed the following class that should work kind of like a method (usually the user will just run Execute()): public abstract class ??? { protected bool hasFailed = false; protected bool hasRun = false; public bool HasFailed { get { return hasFailed; } } public bool HasRun { get { return hasRun; } } private void Restart() { hasFailed = false; hasRun = false; } public bool Execute() { ExecuteImplementation(); bool returnValue = hasFailed; Restart(); return returnValue; } protected abstract void ExecuteImplementation(); } My question is: how should I name this class? Runnable? Method(sounds awkward)?

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  • SQL Count in View as column

    - by alex
    I'm trying to get the result of a COUNT as a column in my view. Please see the below query for a demo of the kind of thing I want (this is just for demo purposes) SELECT ProductID, Name, Description, Price, (SELECT COUNT(*) FROM ord WHERE ord.ProductID = prod.ProductID) AS TotalNumberOfOrders FROM tblProducts prod LEFT JOIN tblOrders ord ON prod.ProductID = ord.ProductID This obviously isn't working... but I was wondering what the correct way of doing this would be?

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  • Where do I put javaassist code?

    - by DutrowLLC
    I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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  • In what package should a "Settings" class be?

    - by Tom
    I've in the middle of building an application but found myself too easily creating new packages without keeping the project's structure in mind. Now, I'm trying to redo the whole project structure on paper first. I am using a Settings class with public properties, accessed as settings for several other classes around the project. Now, since this Settings class applies for the whole project, I am unsure if it should be packaged and if so, in what kind of package should it exist? Or should it be in the root (the default package) with the main application class? I've been thinking about putting it in my utils package, then again I don't think it really is an utlity. Any strategies on how to decide on such package structure for example for a Settings class?

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  • Does Javascript have classes?

    - by Glycerine
    A friend and I had an argument last week. He stated there were no such things as classes in Javascript. I said there was as you can say var object = new Object() he says "as there is no word class used. Its not a class. -- Whats your take on it guys? thanks.

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  • Which design is better (OO Design)?

    - by Tattat
    I have an "Enemy" object, that have many "gun" . Each "gun" can fire "bullet". Storing "gun" is using an array. when the "gun" is fired, the "bullet" will be created. And the enemy object will have an array to store the "bullet". So, I am thinking about the fire method. I am think making a firebulletFromGun in the "enemy". It need have a parameter: "gun". while this method is called. The "enemy" 's bullet will be added in the Array. Another design is writing the fire method in the "gun". The "enemy" use the "gun"'s fire method. And the "gun" will return a "bullet" object, and it will be added in the Array of "enemy". Both method can work, but which way is better? or they are similar the same? plx drop ur ideas/suggestions. thz.

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  • What is the best way to store site configuration data?

    - by DaveDev
    I have a question about storing site configuration data. We have a platform for web applications. The idea is that different clients can have their data hosted and displayed on their own site which sits on top of this platform. Each site has a configuration which determines which panels relevant to the client appear on which pages. The system was originally designed to keep all the configuration data for each site in a database. When the site is loaded all the configuration data is loaded into a SiteConfiguration object, and the clients panels are generated based on the content of this object. This works, but I find it very difficult to work with to apply change requests or add new sites because there is so much data to sift through and it's difficult maintain a mental model of the site and its configuration. Recently I've been tasked with developing a subset of some of the sites to be generated as PDF documents for printing. I decided to take a different approach to how I would define the configuration in that instead of storing configuration data in the database, I wrote XML files to contain the data. I find it much easier to work with because instead of reading meaningless rows of data which are related to other meaningless rows of data, I have meaningful documents with semantic, readable information with the relationships defined by visually understandable element nesting. So now with these 2 approaches to storing site configuration data, I'd like to get the opinions of people more experienced in dealing with this issue on dealing with these two approaches. What is the best way of storing site configuration data? Is there a better way than the two ways I outlined here? note: StackOverflow is telling me the question appears to be subjective and is likely to be closed. I'm not trying to be subjective. I'd like to know how best to approach this issue next time and if people with industry experience on this could provide some input.

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  • Show all data in column

    - by user342391
    I am trying to show all of the data in the 'status' column of my table but am having troubles. What am I doing wrong: <?php $query1 = "SELECT id, status FROM alerts WHERE customerid='".$_SESSION['customerid']."' ORDER BY id LIMIT $start, $limit "; $result = mysql_query($query1); while ($row = mysql_fetch_array($result)) { echo $row['status'] ; } ?>

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  • Difference in Django object creation call

    - by PhilGo20
    I'd like to know if there's a difference between the following two calls to create an object in Django Animal.objects.create(name="cat", sound="meow") and Animal(name="cat", sound="meow") I see both in test cases and I want to make sure I am not missing something. thanks

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  • how to sort JTable by providing column index externally.

    - by user345940
    I would like to implement sorting on JTable by providing column index externally in program. Here is my sample code in which i have initialize JTable, Add one Column and 30 rows to JTable. After rows has been added i am sorting JTable by providing column index 0 but i could not get sorted data. how can i get my first column in sorted order? what's wrong with my code. **Why sortCTableonColumnIndex() method could not sort data for specify column index? ` public class Test { private JTable oCTable; private DefaultTableModel oDefaultTableModel; private JScrollPane oPane; private JTableHeader oTableHeader; private TableRowSorter sorter; public void adddata() { for (int i = 0; i < 30; i++) { Object[] row = new Object[1]; String sValueA = "A"; String sValueB = "A"; row[0] = ""; if (i % 2 == 0) { if (i < 15) { sValueA = sValueA + sValueA; row[1] = sValueA; } else { if (i == 16) { sValueB = "D"; row[1] = sValueA; } else { sValueB = sValueB + sValueB; row[1] = sValueA; } } } else { if (i < 15) { sValueB = sValueB + sValueB; row[1] = sValueB; } else { if (i == 17) { sValueB = "C"; row[1] = sValueB; } else { sValueB = sValueB + sValueB; row[1] = sValueB; } } } } } public void createTable() { oCTable = new JTable(); oDefaultTableModel = new DefaultTableModel(); oCTable.setModel(oDefaultTableModel); oTableHeader = oCTable.getTableHeader(); oCTable.setAutoResizeMode(oCTable.AUTO_RESIZE_OFF); oCTable.setFillsViewportHeight(true); JTable oTable = new LineNumberTable(oCTable); oPane = new JScrollPane(oCTable); oPane.setRowHeaderView(oTable); JPanel oJPanel = new JPanel(); oJPanel.setLayout(new BorderLayout()); oJPanel.add(oPane, BorderLayout.CENTER); JDialog oDialog = new JDialog(); oDialog.add(oJPanel); oDialog.setPreferredSize(new Dimension(500, 300)); oDialog.pack(); oDialog.setVisible(true); } public void insert() { oDefaultTableModel.addColumn("Name"); int iColumnPlace = ((DefaultTableModel) oCTable.getModel()).findColumn("Name"); CellRendererForRowHeader oCellRendererForRowHeader = new CellRendererForRowHeader(); TableColumn Column = oCTable.getColumn(oTableHeader.getColumnModel().getColumn(iColumnPlace).getHeaderValue()); Column.setPreferredWidth(300); Column.setMaxWidth(300); Column.setMinWidth(250); Column.setCellRenderer(oCellRendererForRowHeader); for (int i = 0; i < 30; i++) { Object[] row = new Object[1]; String sValueA = "A"; if (i % 2 == 0) { if (i < 15) { sValueA = sValueA + "a"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { if (i == 16) { sValueA = sValueA + "b"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { sValueA = sValueA + "c"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } } } else { if (i < 15) { sValueA = sValueA + "d"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { if (i == 17) { sValueA = sValueA + "e"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } else { sValueA = sValueA + "f"; oDefaultTableModel.insertRow(oCTable.getRowCount(), new Object[]{""}); oDefaultTableModel.setValueAt(sValueA, i, 0); } } } } } public void showTable() { createTable(); insert(); sortCTableonColumnIndex(0, true); } public void sortCTableonColumnIndex(int iColumnIndex, boolean bIsAsc) { sorter = new TableRowSorter(oDefaultTableModel); List<RowSorter.SortKey> sortKeys = new ArrayList<RowSorter.SortKey>(); if (bIsAsc) { sortKeys.add(new RowSorter.SortKey(iColumnIndex, SortOrder.ASCENDING)); } else { sortKeys.add(new RowSorter.SortKey(iColumnIndex, SortOrder.DESCENDING)); } sorter.setSortKeys(sortKeys); oDefaultTableModel.fireTableStructureChanged(); oCTable.updateUI(); } public static void main(String[] argu) { Test oTest = new Test(); oTest.showTable(); } class CellRendererForRowHeader extends DefaultTableCellRenderer { public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) { JLabel label = null; try { label = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column); if (column == 0) { label.setBackground(new JLabel().getBackground()); label.setForeground(Color.BLACK); } } catch (RuntimeException ex) { } return label; } } class LineNumberTable extends JTable { private JTable mainTable; public LineNumberTable(JTable table) { super(); mainTable = table; setAutoCreateColumnsFromModel(false); setModel(mainTable.getModel()); setAutoscrolls(false); addColumn(new TableColumn()); getColumnModel().getColumn(0).setCellRenderer(mainTable.getTableHeader().getDefaultRenderer()); getColumnModel().getColumn(0).setPreferredWidth(40); setPreferredScrollableViewportSize(getPreferredSize()); } @Override public boolean isCellEditable(int row, int column) { return false; } @Override public Object getValueAt(int row, int column) { return Integer.valueOf(row + 1); } @Override public int getRowHeight(int row) { return mainTable.getRowHeight(); } } } `

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  • PHP Show all data in column

    - by user342391
    I am trying to show all of the data in the 'status' column of my table but am having troubles. What am I doing wrong: <?php $query1 = "SELECT id, status FROM alerts WHERE customerid='".$_SESSION['customerid']."' ORDER BY id LIMIT $start, $limit "; $result = mysql_query($query1); while ($row = mysql_fetch_array($result)) { echo $row['status'] ; } ?>

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  • How to extend this design for a generic converter in java?

    - by Jay
    Here is a small currency converter piece of code: public enum CurrencyType { DOLLAR(1), POUND(1.2), RUPEE(.25); private CurrencyType(double factor) { this.factor = factor; } private double factor; public double getFactor() { return factor; } } public class Currency { public Currency(double value, CurrencyType type) { this.value = value; this.type = type; } private CurrencyType type; private double value; public CurrencyType getCurrencyType() { return type; } public double getCurrencyValue() { return value; } public void setCurrenctyValue(double value){ this.value = value; } } public class CurrencyConversion { public static Currency convert(Currency c1, Currency c2) throws Exception { if (c1 != null && c2 != null) { c2.setCurrenctyValue(c1.getCurrencyValue() * c1.getCurrencyType().getFactor() * c2.getCurrencyType().getFactor()); return c2; } else throw new Exception(); } } I would like to improve this code to make it work for different units of conversion, for example: kgs to pounds, miles to kms, etc etc. Something that looks like this: public class ConversionManager<T extends Convertible> { public T convert(T c1, T c2) { //return null; } } Appreciate your ideas and suggestions.

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  • Circular dependency with generics

    - by devoured elysium
    I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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  • Designing different Factory classes (and what to use as argument to the factories!)

    - by devoured elysium
    Let's say we have the following piece of code: public class Event { } public class SportEvent1 : Event { } public class SportEvent2 : Event { } public class MedicalEvent1 : Event { } public class MedicalEvent2 : Event { } public interface IEventFactory { bool AcceptsInputString(string inputString); Event CreateEvent(string inputString); } public class EventFactory { private List<IEventFactory> factories = new List<IEventFactory>(); public void AddFactory(IEventFactory factory) { factories.Add(factory); } //I don't see a point in defining a RemoveFactory() so I won't. public Event CreateEvent(string inputString) { try { //iterate through all factories. If one and only one of them accepts //the string, generate the event. Otherwise, throw an exception. return factories.Single(factory => factory.AcceptsInputString(inputString)).CreateEvent(inputString); } catch (InvalidOperationException e) { throw new InvalidOperationException("No valid factory found to generate this kind of Event!", e); } } } public class SportEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("SportEvent1"); } public Event CreateEvent(string inputString) { return new SportEvent1(); } } public class MedicalEvent1Factory : IEventFactory { public bool AcceptsInputString(string inputString) { return inputString.StartsWith("MedicalEvent1"); } public Event CreateEvent(string inputString) { return new MedicalEvent1(); } } And here is the code that runs it: static void Main(string[] args) { EventFactory medicalEventFactory = new EventFactory(); medicalEventFactory.AddFactory(new MedicalEvent1Factory()); medicalEventFactory.AddFactory(new MedicalEvent2Factory()); EventFactory sportsEventFactory = new EventFactory(); sportsEventFactory.AddFactory(new SportEvent1Factory()); sportsEventFactory.AddFactory(new SportEvent2Factory()); } I have a couple of questions: Instead of having to add factories here in the main method of my application, should I try to redesign my EventFactory class so it is an abstract factory? It'd be better if I had a way of not having to manually add EventFactories every time I want to use them. So I could just instantiate MedicalFactory and SportsFactory. Should I make a Factory of factories? Maybe that'd be over-engineering? As you have probably noticed, I am using a inputString string as argument to feed the factories. I have an application that lets the user create his own events but also to load/save them from text files. Later, I might want to add other kinds of files, XML, sql connections, whatever. The only way I can think of that would allow me to make this work is having an internal format (I choose a string, as it's easy to understand). How would you make this? I assume this is a recurrent situation, probably most of you know of any other more intelligent approach to this. I am then only looping in the EventFactory for all the factories in its list to check if any of them accepts the input string. If one does, then it asks it to generate the Event. If you find there is something wrong or awkward with the method I'm using to make this happen, I'd be happy to hear about different implementations. Thanks! PS: Although I don't show it in here, all the different kind of events have different properties, so I have to generate them with different arguments (SportEvent1 might have SportName and Duration properties, that have to be put in the inputString as argument).

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  • Reverse mapping from a table to a model in SQLAlchemy

    - by Jace
    To provide an activity log in my SQLAlchemy-based app, I have a model like this: class ActivityLog(Base): __tablename__ = 'activitylog' id = Column(Integer, primary_key=True) activity_by_id = Column(Integer, ForeignKey('users.id'), nullable=False) activity_by = relation(User, primaryjoin=activity_by_id == User.id) activity_at = Column(DateTime, default=datetime.utcnow, nullable=False) activity_type = Column(SmallInteger, nullable=False) target_table = Column(Unicode(20), nullable=False) target_id = Column(Integer, nullable=False) target_title = Column(Unicode(255), nullable=False) The log contains entries for multiple tables, so I can't use ForeignKey relations. Log entries are made like this: doc = Document(name=u'mydoc', title=u'My Test Document', created_by=user, edited_by=user) session.add(doc) session.flush() # See note below log = ActivityLog(activity_by=user, activity_type=ACTIVITY_ADD, target_table=Document.__table__.name, target_id=doc.id, target_title=doc.title) session.add(log) This leaves me with three problems: I have to flush the session before my doc object gets an id. If I had used a ForeignKey column and a relation mapper, I could have simply called ActivityLog(target=doc) and let SQLAlchemy do the work. Is there any way to work around needing to flush by hand? The target_table parameter is too verbose. I suppose I could solve this with a target property setter in ActivityLog that automatically retrieves the table name and id from a given instance. Biggest of all, I'm not sure how to retrieve a model instance from the database. Given an ActivityLog instance log, calling self.session.query(log.target_table).get(log.target_id) does not work, as query() expects a model as parameter. One workaround appears to be to use polymorphism and derive all my models from a base model which ActivityLog recognises. Something like this: class Entity(Base): __tablename__ = 'entities' id = Column(Integer, primary_key=True) title = Column(Unicode(255), nullable=False) edited_at = Column(DateTime, onupdate=datetime.utcnow, nullable=False) entity_type = Column(Unicode(20), nullable=False) __mapper_args__ = {'polymorphic_on': entity_type} class Document(Entity): __tablename__ = 'documents' __mapper_args__ = {'polymorphic_identity': 'document'} body = Column(UnicodeText, nullable=False) class ActivityLog(Base): __tablename__ = 'activitylog' id = Column(Integer, primary_key=True) ... target_id = Column(Integer, ForeignKey('entities.id'), nullable=False) target = relation(Entity) If I do this, ActivityLog(...).target will give me a Document instance when it refers to a Document, but I'm not sure it's worth the overhead of having two tables for everything. Should I go ahead and do it this way?

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  • how to invisible a column in gridview

    - by Joby Kurian
    how to invisible a column in gridview.I tried to use this---dataGridView.Columns(0).Visible = False.But its getting an error "Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index".How to do that?

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  • NSTableView with columns bound to different NSArrayControllers

    - by Vyacheslav Karpukhin
    i have NSTableView and two columns in it: NSTableColumn *column = [[[NSTableColumn alloc] initWithIdentifier:@"custId"] autorelease]; [column bind:@"value" toObject:arrC2 withKeyPath:@"arrangedObjects.custId" options:nil]; [table addTableColumn:column]; column = [[[NSTableColumn alloc] initWithIdentifier:@"totalGrams"] autorelease]; [column bind:@"value" toObject:valuationArrC withKeyPath:@"arrangedObjects.totalGrams_double" options:nil]; [table addTableColumn:column]; as you can see, columns bound to different NSArrayControllers. first column shows correct values, but second just shows "(" symbol. but if i swap columns like this: NSTableColumn *column = [[[NSTableColumn alloc] initWithIdentifier:@"totalGrams"] autorelease]; [column bind:@"value" toObject:valuationArrC withKeyPath:@"arrangedObjects.totalGrams_double" options:nil]; [table addTableColumn:column]; column = [[[NSTableColumn alloc] initWithIdentifier:@"custId"] autorelease]; [column bind:@"value" toObject:arrC2 withKeyPath:@"arrangedObjects.custId" options:nil]; [table addTableColumn:column]; then i see values of first column (which was second in the first example) and again "(" in the second column. i don't understand that behaviour. how can i bound two array controllers to one table?

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