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  • Scheduling of jobs in the presence of constraints in Java

    - by Asgard
    I want to know how to implement a solution to this problem: A task is performed by running, by more people, some basic jobs with known duration in time units (days, months, etc..). The execution of the jobs could lead to the existence of time constraints: a job, for example, can not start if it is not over another (or others) and so on. I want to design and build an application to check the correctness of jobs activities and to propose a schedule of jobs, if any, which is respectful of the constraints. Input must provide the jobs and associated constraints. The expected output is the scheduling of jobs. The specification of an elementary job consists of the pair <jobs-id, duration> A constraint is expressed by means of a quintuple of the type <S/E, id-job1, B/A, S/E, id-job2> the beginning (S) or the end (E) of a jobs Id-job1, must take place before (B) / after (A) of the beginning (S) / end (E) of the Id-job2. If there are no dependencies between some jobs, then jobs can be done before, in parallel. As a simple example, consider the input: jobs jobs(0, 3) jobs(1, 4) jobs(2, 5) jobs(3, 3) jobs(4, 3) constraints constraints(S, 1, A, E, 0) constraints(S, 4, A, E, 2) Possible output: t 0 1 2 3 4 0 * - * * - 1 * - * * - 2 * - * * - 3 * - * * - 4 - * * - - 5 - * * - - 6 - * - - * 7 - * - - * 8 - * - - * 9 - - - - * How to code an efficient java scheduler(avoiding the intense backtracking if is possible) to manage the jobs with these constraints, as described??? I have seen a discussion on a thread in a forum where an user seems has solved the problem easily, but He haven't given enough details to the users to compile a working project(I'm noob), and I'm interested to know an effective implementation of the solution (without using external libraries). If someone help me, I'll give to him a very good feedback ;)

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  • Best way to enforce inter-table constraints inside database

    - by FerranB
    I looking for the best way to check for inter-table constraints an step forward of foreing keys. For instance, to check if a date child record value is between a range date on two parent rows columns. For instance: Parent table ID DATE_MIN DATE_MAX ----- ---------- ---------- 1 01/01/2009 01/03/2009 ... Child table PARENT_ID DATE ---------- ---------- 1 01/02/2009 1 01/12/2009 <--- HAVE TO FAIL! ... I see two approaches: Create materialized views on-commit as shown in this article (or other equivalent on other RDBMS). Use stored-procedures and triggers. Any other approach? Which is the best option? UPDATE: The motivation of this question is not about "putting the constraints on database or on application". I think this is a tired question and anyone does the way she loves. And, I'm sorry for detractors, I'm developing with constraints on database. From here, the question is "which is the best option to manage inter-table constraints on database?". I'm added "inside database" on the question title. UPDATE 2: Some one added the "oracle" tag. Of course materialized views are oracle-tools but I'm interested on any option regardless it's on oracle or others RDBMSs.

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  • How to program for constraints/rules

    - by Gaurav
    First the background, during interviews in the past, many times I have been asked to design some or other variation of card game as programming puzzle, and I have tried to design it in OO way, but I have never been satisfied with my solutions. However it was not until recently that I realized that I had been approaching the problem from the wrong direction. Specifically I was trying to solve the problem by modeling individual card as an object. Problem with this is individual cards don't have any non-trivial intrinsic behavior and therefore are not suitable (or primary) candidate as objects. What is interesting and important about cards are rules and constraints, such as there could be only four suits, or only thirteen cards in each suit. Of course, then there are any number of rules for games. So my questions are Are there any idioms/constructs/patterns to program for rules & constraints. How many in 1 can be applied in conjunction with OO paradigm.

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  • Should I specify both INDEX and UNIQUE INDEX?

    - by Matt Huggins
    On one of my PostgreSQL tables, I have a set of two fields that will be defined as being unique in the table, but will also both be used together when selecting data. Given this, do I only need to define a UNIQUE INDEX, or should I specify an INDEX in addition to the UNIQUE INDEX? This? CREATE UNIQUE INDEX mytable_col1_col2_idx ON mytable (col1, col2); Or this? CREATE UNIQUE INDEX mytable_col1_col2_uidx ON mytable (col1, col2); CREATE INDEX mytable_col1_col2_idx ON mytable (col1, col2);

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  • Hash of unique value = unique hash?

    - by Nebs
    Theoretically does hashing a unique value yield a unique value? Let's say I have a DB table with 2 columns: id and code. id is an auto-incrementing int and code is a varchar. If I do ... $code = sha1($id); ... and then store $code into the same row as $id. Will my code column be unique as well? What about if I append the current time? eg: $code = sha1($id . time()); Thanks.

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  • Unique Business Value vs. Unique IT

    - by barry.perkins
    When the age of computing started, technology was new, exciting, full of potential and had a long way to grow. Vendor architectures were proprietary, and limited in function at first, growing in capability and complexity over time. There were few if any "standards", let alone "open standards" and the concepts of "open systems", and "open architectures" were far in the future. Companies employed intelligent, talented and creative people to implement the best possible solutions for their company. At first, those solutions were "unique" to each company. As time progressed, standards emerged, companies shared knowledge, business capability supplied by technology grew, and companies continued to expand their use of technology. Taking advantage of change required companies to struggle through periodic "revolutionary" change cycles, struggling through costly changes that were fraught with risk, resulted in solutions with an increasingly shorter half-life, and frequently required altering existing business processes and retraining employees and partner businesses. The pace of technological invention and implementation grew at an ever increasing rate, making the "revolutionary" approach based upon "proprietary" or "closed" architectures or technologies no longer viable. Concurrent with the advancement of technology, the rate of change in business increased, leading us to the incredibly fast paced, highly charged, and competitive global economy that we have today, where the most successful companies are companies that are good at implementing, leveraging and exploiting change. Fast forward to today, a world where dramatic changes in business and technology happen continually, a world where "evolutionary" change is crucial. Companies can no longer afford to build "unique IT", nor can they afford regular intervals of "revolutionary" change, with the associated costs and risks. Human ingenuity was once again up to the task, turning technology into a platform supporting business through evolutionary change, by employing "open": open standards; open systems; open architectures; and open solutions. Employing "open", enables companies to implement systems based upon technology, capability and standards that will evolve over time, providing a solid platform upon which a company can drive business needs, requirements, functions, and processes down into the technology, rather than exposing technology to the business, allowing companies to focus on providing "unique business value" rather than "unique IT". The big question! Does moving from "older" technology that no longer meets the needs of today's business, to new "open" technology require yet another "revolutionary change"? A "revolutionary" change with a short half-life, camouflaging reality with great marketing? The answer is "perhaps". With the endless options available to choose from, it is entirely possible to implement a solution that may work well today, but in 5 years time will become yet another albatross for the company to bear. Some solutions may look good today, solving a budget challenge by reducing cost, or solving a specific tactical challenge, but result in highly complex environments, that may be difficult to manage and maintain and limit the future potential of your business. Put differently, some solutions might push today's challenge into the future, resulting in a more complex and expensive solution. There is no such thing as a "1 size fits all" IT solution for business. If all companies implemented business solutions based upon technology that required, or forced the same business processes across all businesses in an industry, it would be extremely difficult to show competitive advantage through "unique business value". It would be equally difficult to "evolve" to meet or exceed business needs and keep up with today's rapid pace of change. How does one ensure that they do not jump from one trap directly into another? Or to put it positively, there are solutions available today that can address these challenges and issues. How does one ensure that the buying decision of today will serve the business well for years into the future? Intelligent & Informed decisions - "buying right" In a previous blog entry, we discussed the value of linking tactical to strategic The key is driving the focus to what is best for your business, handling today's tactical issues while also aligning with a roadmap/strategy that is tightly aligned with your strategic business objectives. When considering the plethora of possible options that provide various approaches to solving today's complex business problems, it is extremely important to ensure that vendors supplying those options, focus on what is best for your business, supplying sufficient information, providing adequate answers to questions, addressing challenges, issues, concerns and objections honestly and openly, and focus on supplying solutions that are tailored for, and deliver the most business value possible for your business. Here are a few questions to consider relative to the proposed options that should help ensure that today's solution doesn't become tomorrow's problem. Do the proposed solutions: Solve the problem(s) you are trying to address? Provide a solid foundation upon which to grow/enhance your business? Provide tactical gains that align with and enable your strategic business goals/objectives? Provide an infrastructure that can be leveraged with subsequent projects? Solve problems for the business overall, the lines of business, or just IT? Simplify your current environment Provide the basis for business: Efficiency Agility Clarity governance, risk, compliance real time business visibility and trend analysis Does your IT staff have the knowledge/experience to successfully manage the proposed systems once they are deployed in production? Done well, you will be presented with options tailored to your business, that enable you to drive the "unique business value" necessary to help your business stand out from others, creating a distinct competitive advantage, delivering what your customers need, when they need it, so you can attract new customers, new business, and grow top line revenue, all at a cost that provides a strong Return on Investment/Return on Assets. The net result is growth with managed cost providing significantly improved profit margin and shareholder value.

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  • SQL Server Constraints Across Tables

    - by chama
    I have a SQL Server database with an Apartment table (which has columns FloorNum and BuildingID) and an ApartmentBuilding table (with column NumFloors). Is there any way to set up a constraint (using the SQL Server UI) to check that Apartment.FloorNum is greater than ApartmentBuilding.NumFloors? I tried this: FloorNum > ApartmentBuilding.NumFloors but now I realize that I somehow have to join the columns on the BuildingID, but I have no idea how to do that within a constraint. Thanks for your help!

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  • T-SQL Unique constraint locked the SQL server

    - by PaN1C_Showt1Me
    HI ! This is my table: CREATE TABLE [ORG].[MyTable]( .. [my_column2] UNIQUEIDENTIFIER NOT NULL CONSTRAINT FK_C1 REFERENCES ORG.MyTable2 (my_column2), [my_column3] INT NOT NULL CONSTRAINT FK_C2 REFERENCES ORG.MyTable3 (my_column3) .. ) I've written this constraint to assure that combination my_column2 and my_column3 is always unique. ALTER TABLE [ORG].[MyTable] ADD CONSTRAINT UQ_MyConstraint UNIQUE NONCLUSTERED ( my_column2, my_column3 ) But then suddenly.. The DB stopped responding.. there is a lock or something.. Do you have any idea why? What is bad with the constraint?

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  • UNIQUE CONSTRAINT on a column from foreign table in SQL Server 2008

    - by bodziec
    I have two tables: create table [dbo].[Main] ( [ID] [int] identity(1,1) primary key not null, [Sign] [char](1) not null ) create table [dbo].[Names] ( [ID_Main][int] primary key not null, [Name][nvarchar](128) not null, constraint [FK_Main_Users] foreign key ([ID_Main]) references [dbo].[Main]([ID]), constraint [CK_Name] unique ([Name], [Sign]) ) The problem is with the second constraint CK_Name Is there a way to make a constraint target column from a foreign table?

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  • UNIQUE CONSTRAINT on a column from foreign table in MSSQL2008

    - by bodziec
    Hi, I have two tables: create table [dbo].[Main] ( [ID] [int] identity(1,1) primary key not null, [Sign] [char](1) not null ) create table [dbo].[Names] ( [ID_Main][int] primary key not null, [Name][nvarchar](128) not null, constraint [FK_Main_Users] foreign key ([ID_Main]) references [dbo].[Main]([ID]), constraint [CK_Name] unique ([Name], [Sign]) ) The problem is with the second constraint CK_Name Is there a way to make a constraint target column from a foreign table?

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  • Java JTextPane JScrollPane Display Issue

    - by ikurtz
    The following class implements a chatGUI. When it runs okay the screen looks like this: Fine ChatGUI The problem is very often when i enter text of large length ie. 50 - 100 chars the gui goes crazy. the chat history box shrinks as shown in this image. Any ideas regarding what is causing this? Thank you. package Sartre.Connect4; import javax.swing.*; import java.net.*; import java.awt.*; import java.awt.event.*; import javax.swing.text.StyledDocument; import javax.swing.text.Style; import javax.swing.text.StyleConstants; import javax.swing.text.BadLocationException; import java.io.BufferedOutputStream; import javax.swing.text.html.HTMLEditorKit; import java.io.FileOutputStream; import java.io.IOException; import java.io.FileNotFoundException; import javax.swing.filechooser.FileNameExtensionFilter; import javax.swing.JFileChooser; /** * Chat form class * @author iAmjad */ public class ChatGUI extends JDialog implements ActionListener { /** * Used to hold chat history data */ private JTextPane textPaneHistory = new JTextPane(); /** * provides scrolling to chat history pane */ private JScrollPane scrollPaneHistory = new JScrollPane(textPaneHistory); /** * used to input local message to chat history */ private JTextPane textPaneHome = new JTextPane(); /** * Provides scrolling to local chat pane */ private JScrollPane scrollPaneHomeText = new JScrollPane(textPaneHome); /** * JLabel acting as a statusbar */ private JLabel statusBar = new JLabel("Ready"); /** * Button to clear chat history pane */ private JButton JBClear = new JButton("Clear"); /** * Button to save chat history pane */ private JButton JBSave = new JButton("Save"); /** * Holds contentPane */ private Container containerPane; /** * Layout GridBagLayout manager */ private GridBagLayout gridBagLayout = new GridBagLayout(); /** * GridBagConstraints */ private GridBagConstraints constraints = new GridBagConstraints(); /** * Constructor for ChatGUI */ public ChatGUI(){ setTitle("Chat"); // set up dialog icon URL url = getClass().getResource("Resources/SartreIcon.jpg"); ImageIcon imageIcon = new ImageIcon(url); Image image = imageIcon.getImage(); this.setIconImage(image); this.setAlwaysOnTop(true); setLocationRelativeTo(this.getParent()); //////////////// End icon and placement ///////////////////////// // Get pane and set layout manager containerPane = getContentPane(); containerPane.setLayout(gridBagLayout); ///////////////////////////////////////////////////////////// //////////////// Begin Chat History ////////////////////////////// textPaneHistory.setToolTipText("Chat History Window"); textPaneHistory.setEditable(false); textPaneHistory.setPreferredSize(new Dimension(350,250)); scrollPaneHistory.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); scrollPaneHistory.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER); // fill Chat History GridBagConstraints constraints.gridx = 0; constraints.gridy = 0; constraints.gridwidth = 10; constraints.gridheight = 10; constraints.weightx = 100; constraints.weighty = 100; constraints.fill = GridBagConstraints.BOTH; constraints.anchor = GridBagConstraints.CENTER; constraints.insets = new Insets(10,10,10,10); constraints.ipadx = 0; constraints.ipady = 0; gridBagLayout.setConstraints(scrollPaneHistory, constraints); // add to the pane containerPane.add(scrollPaneHistory); /////////////////////////////// End Chat History /////////////////////// ///////////////////////// Begin Home Chat ////////////////////////////// textPaneHome.setToolTipText("Home Chat Message Window"); textPaneHome.setPreferredSize(new Dimension(200,50)); textPaneHome.addKeyListener(new MyKeyAdapter()); scrollPaneHomeText.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS); scrollPaneHomeText.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER); // fill Chat History GridBagConstraints constraints.gridx = 0; constraints.gridy = 10; constraints.gridwidth = 6; constraints.gridheight = 1; constraints.weightx = 100; constraints.weighty = 100; constraints.fill = GridBagConstraints.BOTH; constraints.anchor = GridBagConstraints.CENTER; constraints.insets = new Insets(10,10,10,10); constraints.ipadx = 0; constraints.ipady = 0; gridBagLayout.setConstraints(scrollPaneHomeText, constraints); // add to the pane containerPane.add(scrollPaneHomeText); ////////////////////////// End Home Chat ///////////////////////// ///////////////////////Begin Clear Chat History //////////////////////// JBClear.setToolTipText("Clear Chat History"); // fill Chat History GridBagConstraints constraints.gridx = 6; constraints.gridy = 10; constraints.gridwidth = 2; constraints.gridheight = 1; constraints.weightx = 100; constraints.weighty = 100; constraints.fill = GridBagConstraints.BOTH; constraints.anchor = GridBagConstraints.CENTER; constraints.insets = new Insets(10,10,10,10); constraints.ipadx = 0; constraints.ipady = 0; gridBagLayout.setConstraints(JBClear, constraints); JBClear.addActionListener(this); // add to the pane containerPane.add(JBClear); ///////////////// End Clear Chat History //////////////////////// /////////////// Begin Save Chat History ////////////////////////// JBSave.setToolTipText("Save Chat History"); constraints.gridx = 8; constraints.gridy = 10; constraints.gridwidth = 2; constraints.gridheight = 1; constraints.weightx = 100; constraints.weighty = 100; constraints.fill = GridBagConstraints.BOTH; constraints.anchor = GridBagConstraints.CENTER; constraints.insets = new Insets(10,10,10,10); constraints.ipadx = 0; constraints.ipady = 0; gridBagLayout.setConstraints(JBSave, constraints); JBSave.addActionListener(this); // add to the pane containerPane.add(JBSave); ///////////////////// End Save Chat History ///////////////////// /////////////////// Begin Status Bar ///////////////////////////// constraints.gridx = 0; constraints.gridy = 11; constraints.gridwidth = 10; constraints.gridheight = 1; constraints.weightx = 100; constraints.weighty = 50; constraints.fill = GridBagConstraints.BOTH; constraints.anchor = GridBagConstraints.CENTER; constraints.insets = new Insets(0,10,5,0); constraints.ipadx = 0; constraints.ipady = 0; gridBagLayout.setConstraints(statusBar, constraints); // add to the pane containerPane.add(statusBar); ////////////// End Status Bar //////////////////////////// // set resizable to false this.setResizable(false); // pack the GUI pack(); } /** * Deals with necessary menu click events * @param event */ public void actionPerformed(ActionEvent event) { Object source = event.getSource(); // Process Clear button event if (source == JBClear){ textPaneHistory.setText(null); statusBar.setText("Chat History Cleared"); } // Process Save button event if (source == JBSave){ // process only if there is data in history pane if (textPaneHistory.getText().length() > 0){ // process location where to save the chat history file JFileChooser chooser = new JFileChooser(); chooser.setMultiSelectionEnabled(false); chooser.setAcceptAllFileFilterUsed(false); FileNameExtensionFilter filter = new FileNameExtensionFilter("HTML Documents", "htm", "html"); chooser.setFileFilter(filter); int option = chooser.showSaveDialog(ChatGUI.this); if (option == JFileChooser.APPROVE_OPTION) { // Set up document to be parsed as HTML StyledDocument doc = (StyledDocument)textPaneHistory.getDocument(); HTMLEditorKit kit = new HTMLEditorKit(); BufferedOutputStream out; try { // add final file name and extension String filePath = chooser.getSelectedFile().getAbsoluteFile() + ".html"; out = new BufferedOutputStream(new FileOutputStream(filePath)); // write out the HTML document kit.write(out, doc, doc.getStartPosition().getOffset(), doc.getLength()); } catch (FileNotFoundException e) { JOptionPane.showMessageDialog(ChatGUI.this, "Application will now close. \n A restart may cure the error!\n\n" + e.getMessage(), "Fatal Error", JOptionPane.WARNING_MESSAGE, null); System.exit(2); } catch (IOException e){ JOptionPane.showMessageDialog(ChatGUI.this, "Application will now close. \n A restart may cure the error!\n\n" + e.getMessage(), "Fatal Error", JOptionPane.WARNING_MESSAGE, null); System.exit(3); } catch (BadLocationException e){ JOptionPane.showMessageDialog(ChatGUI.this, "Application will now close. \n A restart may cure the error!\n\n" + e.getMessage(), "Fatal Error", JOptionPane.WARNING_MESSAGE, null); System.exit(4); } statusBar.setText("Chat History Saved"); } } } } /** * Process return key for sending the message */ private class MyKeyAdapter extends KeyAdapter { @Override @SuppressWarnings("static-access") public void keyPressed(KeyEvent ke) { DateTime dateTime = new DateTime(); String nowdateTime = dateTime.getDateTime(); int kc = ke.getKeyCode(); if (kc == ke.VK_ENTER) { try { // Process only if there is data if (textPaneHome.getText().length() > 0){ // Add message origin formatting StyledDocument doc = (StyledDocument)textPaneHistory.getDocument(); Style style = doc.addStyle("HomeStyle", null); StyleConstants.setBold(style, true); String home = "Home [" + nowdateTime + "]: "; doc.insertString(doc.getLength(), home, style); StyleConstants.setBold(style, false); doc.insertString(doc.getLength(), textPaneHome.getText() + "\n", style); // update caret location textPaneHistory.setCaretPosition(doc.getLength()); textPaneHome.setText(null); statusBar.setText("Message Sent"); } } catch (BadLocationException e) { JOptionPane.showMessageDialog(ChatGUI.this, "Application will now close. \n A restart may cure the error!\n\n" + e.getMessage(), "Fatal Error", JOptionPane.WARNING_MESSAGE, null); System.exit(1); } ke.consume(); } } } }

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  • Poll Results: Foreign Key Constraints

    - by Darren Gosbell
    A few weeks ago I did the following post asking people – if they used foreign key constraints in their star schemas. The poll is still open if you are interested in adding to it, but here is what the chart looks like as of today. (at the bottom of the poll itself there is a link to the live results, unfortunately I cannot link the live results in here as the blogging platform blocks the required javascript)   Interestingly the results are fairly even. Of the 78 respondents, fractionally over half at least aim to start with referential integrity in their star schemas. I did not want to influence the results by sharing my opinion, but my personal preference is to always aim to have foreign key constraints. But at the same time, I am pragmatic about it, I do have projects where for various reasons some constraints are not defined. And I also have other designs that I have inherited, where it would just be too much work to go back and add foreign key constraints. If you are going to implement foreign keys in your star schema, they really need to be there at the start. In fact this poll was was the result of a feature request for BIDSHelper asking for a feature to check for null/missing foreign keys and I am entirely convinced that BIDS is the wrong place for this sort of functionality. BIDS is a design tool, your data needs to be constantly checked for consistency. It's not that I think that it's impossible to get a design working without foreign key constraints, but I like the idea of failing as soon as possible if there is an error and enforcing foreign key constraints lets me "fail early" if there are constancy issues with my data. By far the biggest concern with foreign keys is performance and I suppose I'm curious as to how often people actually measure and quantify this. I worked on a project a number of years ago that had very large data volumes and we did find that foreign key constraints did have a measurable impact, but what we did was to disable the constraints before loading the data, then enabled and checked them afterwards. This saved as time (although not as much as not having constraints at all), but still let us know early in the process if there were any consistency issues. For the people that do not have consistent data, if you have ETL processes that you control that are building your star schema which you also control, then to be blunt you only have yourself to blame. It is the job of the ETL process to make the data consistent. There are techniques for handling situations like missing data as well as  early and late arriving data. Ralph Kimball's book – The Data Warehouse Toolkit goes through some design patterns for handling data consistency. Having foreign key relationships can also help the relational engine to optimize queries as noted in this recent blog post by Boyan Penev

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  • How to set two column unique in SQL.

    - by sxingfeng
    I am creating a table ,in the table two column is unique, I mean columnA and columnB do not have same value: such as : Table X A B 1 2(RIGHT,unique) 2 2(RIGHT, unique) 1 3(RIGHT, not unique) 2 3(RIGHT, not unique) 1 2 (WRONG, not unique) How to create such a table? many thanks!

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  • AWT Textfield behaves weird with MicroSoft JVM

    - by AKh
    Hi, I am facing a weird problem when using MicroSoft JVM to run my Applet. I have an AWT panel with 4 textfields which is added to a dialog box. Everything goes fine until I enter a decimal value into the textfield and close the dialog box. When i reopen the dialog box the textfield inside the panel with all the decimal digits (entered in the previous step) behaves weird. The decimal values along with the WHITE area inside the textfield moves to the left and hides the digits. When I click inside the textfield it becomes normal. The Panel earlier had gridlayout and I even tried changing it to gridbaylayout and still the problem persist. NOTE: All Development are pertained to JRE1.1 to compatibility with MS JVM If any can help me with this it would be a great help. Thanks in advance. . . . . public MyPanel(Dialog myDialog) { Panel panel = new Panel(); this.dialog = myDialog; //Previous code with grid layout /* panel.setLayout(new GridLayout2(4,2,2,2)); panel.add(new Label("Symbol:")); panel.add(symbolField = new TextField("",20)); panel.add(new Label("Quantity:")); panel.add( qtyField = new TextField()); panel.add(new Label("Price per Share:")); panel.add( costField = new TextField()); panel.add(new Label("Date Acquired:")); panel.add( purchaseDate = new TextField() );*/ GridBagLayout gridbag = new GridBagLayout(); System.out.println("######## Created New GridBagLayout"); GridBagConstraints constraints = new GridBagConstraints(); panel.setLayout( gridbag ); constraints = buildConstraints( constraints, 0, 0, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( new Label("Symbol:"), constraints); constraints = buildConstraints( constraints, 1, 0, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( symbolField = new TextField("",20), constraints); constraints = buildConstraints( constraints, 0, 1, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( new Label("Quantity:"), constraints); constraints = buildConstraints( constraints, 1, 1, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( qtyField = new TextField(), constraints); constraints = buildConstraints( constraints, 0, 2, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( new Label("Price per Share:"), constraints); constraints = buildConstraints( constraints, 1, 2, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( costField = new TextField(), constraints); constraints = buildConstraints( constraints, 0, 3, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( new Label("Date Acquired:"), constraints); constraints = buildConstraints( constraints, 1, 3, 1, 1, 1.5, 1 ); constraints.anchor = GridBagConstraints.WEST; constraints.fill = GridBagConstraints.HORIZONTAL; panel.add( purchaseDate = new TextField(), constraints); .............. ......... }

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  • Combining the UNIQUE and CHECK constraints

    - by Bobby
    I have a table with columns a b and c, and if c is false then I only want to allow insertions if columns a and b are unique, but if c is true then a and b do not need to be unique. Example: There can only be one (foo, bar, false) in the table, but no limit on how many (foo, bar, true) there can be. I tried something like CONSTRAINT blah UNIQUE (a,b) AND CHECK (C is TRUE) but I can't figure out the correct syntax.

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  • UNIQUE Constraints in SQL (MS-SQL)

    - by rockbala
    Why are UNIQUE Constraints needed in database ? Can you provide any examples ? Primary Key is UNIQUE by default... Understandable as they are referred in other tables as Foreign keys... relation is needed to connect them for rdbms platform... but why would one refer to other columns as UNIQUE, what is benefit of doing so ?)

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  • UNIQUE Constraints in SQL (SQL Server)

    - by rockbala
    Why are UNIQUE Constraints needed in database ? Can you provide any examples ? Primary Key is UNIQUE by default... Understandable as they are referred in other tables as Foreign keys... relation is needed to connect them for rdbms platform... but why would one refer to other columns as UNIQUE, what is benefit of doing so ?)

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  • unique constraint (w/o Trigger) on "one-to-many" relation

    - by elgcom
    To illustrate the problem, I make an example: A tag_bundle consists of one or more than one tags. A unique tag combination can map to a unique tag_bundle, vice versa. tag_bundle tag tag_bundle_relation +---------------+ +--------+ +---------------+--------+ | tag_bundle_id | | tag_id | | tag_bundle_id | tag_id | +---------------+ +--------+ +---------------+--------+ | 1 | | 100 | | 1 | 100 | +---------------+ +--------+ +---------------+--------+ | 101 | | 1 | 101 | +--------+ +---------------+--------+ There can't be another tag_bundle having the combination from tag 100 and tag 101. How can I ensure such unique constraint when executing SQL "concurrently"!! that is, to prevent concurrently adding two bundles with the same tag combination Adding a simple unique constraint on any table does not work, Is there any solution other than Trigger or explicit lock. I come to only this simple way: make tag combination into string, and let it be unique. tag_bundle (unique on tags) tag tag_bundle_relation +---------------+--------+ +--------+ +---------------+--------+ | tag_bundle_id | tags | | tag_id | | tag_bundle_id | tag_id | +---------------+--------+ +--------+ +---------------+--------+ | 1 | 100,101| | 100 | | 1 | 100 | +---------------+--------+ +--------+ +---------------+--------+ | 101 | | 1 | 101 | +--------+ +---------------+--------+ but it seems not a good way :(

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  • Model login constraints based on time

    - by DaDaDom
    Good morning, for an existing web application I need to implement "time based login constraints". It means that for each user, later maybe each group, I can define timeslots when they are (not) allowed to log in into the system. As all data for the application is stored in database tables, I need to somehow create a way to model this idea in that way. My first approach, I will try to explain it here: Create a tree of login constraints (called "timeslots") with the main "categories", like "workday", "weekend", "public holiday", etc. on the top level, which are in a "sorted" order (meaning "public holiday" has a higher priority than "weekday") for each top level node create subnodes, which have a finer timespan, like "monday", "tuesday", ... below that, create an "hour" level: 0, 1, 2, ..., 23. No further details are necessary. set every member to "allowed" by default For every member of the system create a 1:n relationship member:timeslots which defines constraints, e.g. a member A may have A:monday-forbidden and A:tuesday-forbidden Do a depth-first search at every login and check if the member has a constraint. Why a depth first search? Well, I thought that it may be that a member has the rules: A:monday->forbidden, A:monday-10->allowed, A:mondey-11->allowed So a login on monday at 12:30 would fail, but one at 10:30 succeed. For performance reasons I could break the relational database paradigm and set a flag for every entry in the member-to-timeslots-table which is set to true if the member has information set for "finer" timeslots, but that's a second step. Is this model in principle a good idea? Are there existing models? Thanks.

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  • One check constraint or multiple check constraints?

    - by RenderIn
    Any suggestions on whether fewer check constraints are better, or more? How should they be grouped if at all? Suppose I have 3 columns which are VARCHAR2(1 BYTE), each of which is a 'T'/'F' flag. I want to add a check constraint to each column specifying that only characters IN ('T', 'F') are allowed. Should I have 3 separate check constraints, one for each column: COL_1 IN ('T', 'F') COL_2 IN ('T', 'F') COL_3 IN ('T', 'F') Or a single check constraint: COL_1 IN ('T', 'F') AND COL_2 IN ('T', 'F') AND COL_3 IN ('T', 'F') My thoughts are it is best to keep these three separate, as the columns are logically unrelated to each other. The only case I would have a check constraint that examines more than one column is if there was some relationship between the value in one and the value in another, e.g.: (PARENT_CNT > 0 AND PRIMARY_PARENT IS NOT NULL) OR (PARENT_CNT = 0 AND PRIMARY_PARENT IS NULL)

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  • MVC ActionLink generating NON-Restul URL AFTER adding constraints

    - by brianstewey
    Hello I have a custom route that without constraints generates a Restful URL with an ActionLink. Route - routes.MapRoute( "Blog", // Route name "Blog/{d}/{m}/{y}", // URL with parameters, new { controller = "Blog", action = "Retrieve" } Generates - http://localhost:2875/Blog/12/1/2010 From - <%=Html.ActionLink("Blog Entry - 12/01/2010", "Retrieve", "Blog", new { d = 12, m = 01, y = 2010 }, null)%> If I add constraints like so. routes.MapRoute( "Blog", // Route name "Blog/{d}/{m}/{y}", // URL with parameters, new { controller = "Blog", action = "Retrieve" }, new { d = @"\d{2}", m = @"\d{2}", y = @"\d{4}" } It generates - http://localhost:2875/Blog/Retrieve?d=12&m=1&y=2010 Extra information: it is added before the custom route. Any ideas? Cheers

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  • Mysterious constraints problem with SQL Server 2000

    - by Ramon
    Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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