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  • how to set environment variable in eric IDE

    - by ng0323
    I have no problem running a python script from the terminal, but in eric IDE, I am getting this error: ImportError libcudart.so.6.0: cannot open shared object file: No such file or directory Perhaps it's an enviroment variable that needs to be set. In eric, when I run script, I filled in the environment option as follows. I tried set PATH = usr/local/cuda-6.0/bin or PATH = /usr/local/cuda-6.0/bin or just /usr/local/cuda-6.0/bin and they all didn't work.

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  • Parent variable inheritance methods Unity3D/C#

    - by Timothy Williams
    I'm creating a system where there is a base "Hero" class and each hero inherits from that with their own stats and abilities. What I'm wondering is, how could I call a variable from one of the child scripts in the parent script (something like maxMP = MP) or call a function in a parent class that is specified in each child class (in the parent update is alarms() in the child classes alarms() is specified to do something.) Is this possible at all? Or not? Thanks.

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  • Handling deleted users - separate or same table?

    - by Alan Beats
    The scenario is that I've got an expanding set of users, and as time goes by, users will cancel their accounts which we currently mark as 'deleted' (with a flag) in the same table. If users with the same email address (that's how users log in) wish to create a new account, they can signup again, but a NEW account is created. (We have unique ids for every account, so email addresses can be duplicated amongst live and deleted ones). What I've noticed is that all across our system, in the normal course of things we constantly query the users table checking the user is not deleted, whereas what I'm thinking is that we dont need to do that at all...! [Clarification1: by 'constantly querying', I meant that we have queries which are like: '... FROM users WHERE isdeleted="0" AND ...'. For example, we may need to fetch all users registered for all meetings on a particular date, so in THAT query, we also have FROM users WHERE isdeleted="0" - does this make my point clearer?] (1) continue keeping deleted users in the 'main' users table (2) keep deleted users in a separate table (mostly required for historical book-keeping) What are the pros and cons of either approach?

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  • Dualboot Asus n56v (ubuntu / win 7 x64) - ubuntu doesn't detect partition table made by windows

    - by user76439
    I have an Asus n56v and I've got troubles installing Ubuntu 12.04 x64. I already have installed Windows 7 x64! The hard drive is: Hitachi HTS547575A9E384 My problem: The installation program doesn't recognize the already existing partitions and is offering only options where there are partitions. Can someone help me out? Is this an ACPI/IDE conflict, missing driver or conflict with Windows 7? (I'm not an expert on Linux, only working sometimes with it.) I now tried out some options concerning EFI with a GTP-table. Everything worked but I wasn't able to fix a dual boot (Windows boot loader) nor with GRUB2. The laptop is still having a BIOS, but is able to boot DVDs/CDs in EFI-mode. Now I try to avoid EFI and GTP using the old windows MBR style. I reinstalled Windows, so far no problem. When I want to try to install Ubuntu, it doesn't detect the already existing partition table. It is just showing me an empty space for the whole disk. Other threads like Ubuntu 12.04 does not see windows already install on my computer (dual installation) don't help me out. os-prober shows me a correct result. I don't know how to deal with gdisk as shown in Installer doesn't detect existing partition table/windows 7 partition. I have 750GB for the whole disk. I'm using: 90GB for Windows reserved partition + system partition, 500GB for data and the rest should be for SWAP and linux-system. How can I make Ubuntu detect the partition table?

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  • CONFIG_ATH_USER_REGD variable In Ununtu

    - by BigGenius
    There is a CONFIG_ATH_USER_REGD variable in OpenWrt that allows the user to override the default settings of the wireless NIC. Unfortunately grepping the Arch kernel config doesn't seem to have that, and since OpenWrt has its fair share of hacking and patches, I don't know if that's something they added or that's provided e.g. in compat-wireless. Does this setting exists for Ubuntu or BackTrack-Linux?

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  • Variable number of GUI Buttons

    - by Wakaka
    I have a generic HTML5 Canvas GUI Button class and a Scene class. The Scene class has a method called createButton(), which will create a new Button with onclick parameter and store it in a list of buttons. I call createButton() for all UI buttons when initializing the Scene. Because buttons can appear and disappear very often during rendering, Scene would first deactivate all buttons (temporarily remove their onclick, onmouseover etc property) before each render frame. During rendering, the renderer would then activate the required buttons for that frame. The problem is that part of the UI requires a variable number of buttons, and their onclick, onmouseover etc properties change frequently. An example is a buffs system. The UI will list all buffs as square sprites for the current unit selected, and mousing over each square will bring up a tooltip with some information on the buff. But the number of buffs is variable thus I won't know how many buttons to create at the start. What's the best way to solve this problem? P.S. My game is in Javascript, and I know I can use HTML buttons, but would like to make my game purely Canvas-based. Create buttons on-the-fly during rendering. Thus I will only have buttons when I require them. After the render frame these buttons would be useless and removed. Create a fixed set of buttons that I'm going to assume the number of buffs per unit won't exceed. During each render frame activate the buttons accordingly and set their onmouseover property. Assign a button to each Buff instance. This sounds wrong as the buff button is a part of the GUI which can only have one unit selected. Assigning a button to every single Buff in the game seems to be overkill. Also, I would need to change the button's position every render frame since its order in the unit's list of buffs matter. Any other solutions? I'm actually quite for idea (1) but am worried about the memory/time issues of creating a new Button() object every render frame. But this is in Javascript where object creation is oh-so-common ({} mainly) due to automatic garbage collection. What is your take on this? Thanks!

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  • How do I access variable values from one view controller in another?

    - by Thomas
    Hello all, I have an integer variable (time) in one view controller whose value I need in another view controller. Here's the code: MediaMeterViewController // TRP - On Touch Down event, start the timer -(IBAction) startTimer { time = 0; // TRP - Start a timer timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateTimer) userInfo:nil repeats:YES]; [timer retain]; // TRP - Retain timer so it is not accidentally deallocated } // TRP - Method to update the timer display -(void)updateTimer { time++; // NSLog(@"Seconds: %i ", time); if (NUM_SECONDS == time) [timer invalidate]; } // TRP - On Touch Up Inside event, stop the timer, decide stress level, display results -(IBAction) btn_MediaMeterResults { [timer invalidate]; NSLog(@"Seconds: %i ", time); ResultsViewController *resultsView = [[ResultsViewController alloc] initWithNibName:@"ResultsViewController" bundle:nil]; [self.view addSubview:resultsView.view]; } And in ResultsViewController, I want to process time based on its value ResultsViewController - (void)viewDidLoad { if(time < 3) {// Do something} else if ((time > 3) && (time < 6)) {// Do something else} //etc... [super viewDidLoad]; } I'm kind of unclear on when @property and @synthesize is necessary. Is that the case in this situation? Any help would be greatly appreciated. Thanks! Thomas

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  • Variable length argument list - How to understand we retrieved the last argument?

    - by hkBattousai
    I have a Polynomial class which holds coefficients of a given polynomial. One of its overloaded constructors is supposed to receive these coefficients via variable argument list. template <class T> Polynomial<T>::Polynomial(T FirstCoefficient, ...) { va_list ArgumentPointer; va_start(ArgumentPointer, FirstCoefficient); T NextCoefficient = FirstCoefficient; std::vector<T> Coefficients; while (true) { Coefficients.push_back(NextCoefficient); NextCoefficient = va_arg(ArgumentPointer, T); if (/* did we retrieve all the arguments */) // How do I implement this? { break; } } m_Coefficients = Coefficients; } I know that we usually pass an extra parameter which tells the recipient method the total number of parameters, or we pass a sentimental ending parameter. But in order to keep thing short and clean, I don't prefer passing an extra parameter. Is there any way of doing this without modifying the method signature in the example?

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  • Improved technique to store a filename in a variable?

    - by SDGuero
    Greetings, I need to store the filename of a log into a variable so my script can perform some checks on the daily log files. These logs always have a different name because they have a timestamp in the name. Currently I'm using a hodge podged method that pipes an ls command to sed, sort, cut, and tail in order to get the name out. CRON_LOG=$(ls -1 $LOGS_DIR/fetch_cron_{true,false}_$CRON_DATE*.log 2> /dev/null | sed 's/^[^0-9][^0-9]*\([0-9][0-9]*\).*/\1 &/' | sort -n | cut -d ' ' -f2- | tail -1 ) UPDATE: $CRON_DATE is supplied as an argument to the script. It is the date (to the day) that the log was created on. Sometimes multiple logs will exist for the same day so I want this to get the most recent one. A typical filename is fetch_cron_false_031810090452.log I'm pretty sure I kluged this together from some stuff I found google a few months ago. it works now but I'm not really happy with the technique. I have some ideas about how to do this better but I have had great success on this site before and thought it might be best to refer to the stackoverflow gods first. All answers are greatly appreciated. Thanks, Ryan

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  • python - tkinter - update label from variable

    - by Tom
    I wrote a python script that does some stuff to generate and then keep changing some text stored as a string variable. This works, and I can print the string each time it gets changed. Problems have arisen while trying to display that output in a GUI (just as a basic label) using tkinter. I can get the label to display the string for the first time... but it never updates. This is really the first time I have tried to use tkinter, so it's likely I'm making a foolish error. What I've got looks logical to me, but I'm evidently going wrong somewhere! from tkinter import * outputText = 'Ready' counter = int(0) root = Tk() root.maxsize(400, 400) var = StringVar() l = Label(root, textvariable=var, anchor=NW, justify=LEFT, wraplength=398) l.pack() var.set(outputText) while True: counter = counter + 1 #do some stuff that generates string as variable 'result' outputText = result #do some more stuff that generates new string as variable 'result' outputText = result #do some more stuff that generates new string as variable 'result' outputText = result if counter == 5: break root.mainloop() I also tried: from tkinter import * outputText = 'Ready' counter = int(0) root = Tk() root.maxsize(400, 400) var = StringVar() l = Label(root, textvariable=var, anchor=NW, justify=LEFT, wraplength=398) l.pack() var.set(outputText) while True: counter = counter + 1 #do some stuff that generates string as variable 'result' outputText = result var.set(outputText) #do some more stuff that generates new string as variable 'result' outputText = result var.set(outputText) #do some more stuff that generates new string as variable 'result' outputText = result var.set(outputText) if counter == 5: break root.mainloop() In both cases, the label will show 'Ready' but won't update to change that to the strings as they're generated later. After a fair bit of googling and looking through answers on this site, I thought the solution might be to use update_idletasks - I tried putting that in after each time the variable was changed, but it didn't help. It also seems possible I am meant to be using trace and callback somehow to make all this work...but I can't get my head around how that works (I tried, but didn't manage to make anything that even looked like it would do something, let alone actually worked). I'm still very new to both python and especially tkinter, so, any help much appreciated but please spell it out for me if you can :)

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  • Objective C, Linking Error with extern variable..

    - by LCYSoft
    I have a very simple java code like this. I don't have any idea how to do this in Objective C. Especially, the static part which calls the getLocalAddress() method and assign it into the static string variable. I know how to set a static variable and a static method in Objective but I dont know how to implement that static { } part in java. Thanks in advance... public class Address { public static String localIpAddress; static { localIpAddress = getLocalIpAddress(); } public Address() { } static String getLocalIpAddress() { //do something to get local ip address } } I added this in my .h file #import <Foundation/Foundation.h> extern NSString *localIpAddress; @class WifiAddrss; @interface Address : NSObject { } @end And my .m file looks like #import "Address.h" #import "WifiAddress.h" @implementation Address +(void)initialize{ if(self == [Address class]){ localIpAddress = [self getLocalIpAddress]; } } +(NSString *)getLocalIpAddress{ return address here } -(id)init{ self = [super init]; if (self == nil){ NSLog(@"init error"); } return self; } @end And Now I am getting a linking error and it complains about "extern NSString *localIpAddress" part. If I change the extern to static, it works fine. But what I wanted to do is that I want make the scope of "localIpAddress" variable as grobal. Since if I put "static" in front of a variable in Objective-C then the variable is only visible in the class. But this time, I want to make that as a grobal variable. So my question is how to make "localIpAddress" variable as a grobal variable which is initialized once when the first time Address class is created.. Thanks in advance...

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  • IE7 is making my life miserable! Getting gaps between html table columns (w/ colspan) with css togg

    - by Art Peterson
    Copy/paste this html code snippet and try it out in IE7. When you toggle the hidden columns it leaves a gap between the columns. In Firefox it works fine, the columns touch when minimized. Haven't tried IE8 yet, would be curious to hear how it works there. Any ideas? I've tried a bunch of things in the CSS like table-layout:fixed but no luck. Note: Not looking for a different toggling method because the table I'm really dealing with is 50+ columns wide and 4000+ rows so looping/jquery techniques are too slow. Here's the code - if someone can re-post a working version of it I'll instantly give them the check and be forever in your debt! <DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <script> function toggle() { var tableobj = document.getElementById("mytable"); if (tableobj.className == "") { tableobj.className = "hide1 hide2"; } else { tableobj.className = ""; } } </script> <style> table { border-collapse: collapse; } td, th { border: 1px solid silver; } .hide1 .col1 { display: none; } .hide2 .col2 { display: none; } </style> </head> <body> <input type="button" value="toggle" onclick="toggle();" /> <table id="mytable"> <tr> <th>A</th> <th colspan="2">B</th> <th colspan="2" class="col1">B1</th> <th colspan="2">C</th> <th colspan="2" class="col2">C1</th> </tr> <tr> <td>123</td> <td>456</td> <td>789</td> <td class="col1">123</td> <td class="col1">456</td> <td>789</td> <td>123</td> <td class="col2">456</td> <td class="col2">789</td> </tr> </table> </body> </html>

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  • Sorting the columns of an HTML table using JQuery

    - by nikolaosk
    In this post I will show you how easy is to sort the columns of an HTML table. I will use an external library,called Tablesorter which makes life so much easier for developers. ?here are other posts in my blog regarding JQuery.You can find them all here. You can find another post regarding HTML tables and JQuery here. We will demonstrate this with a step by step example. I will use Visual Studio 2012 Ultimate. You can also use Visual Studio 2012 Express Edition. You can also use VS 2010 editions.   1) Launch Visual Studio. Create an ASP.Net Empty Web application. Choose an appropriate name for your application. 2) Add a web form, default.aspx page to the application. 3) Add a table from the HTML controls tab control (from the Toolbox) on the default.aspx page 4) Now we need to download the JQuery library. Please visit the http://jquery.com/ and download the minified version.Then we need to download the Tablesorter JQuery plugin. Please donwload it, here. 5) We need to reference the JQuery library and the external JQuery Plugin. In the head section ? add the following lines.   <script src="jquery-1_8_2_min.js" type="text/javascript"></script>  <script src="jquery.tablesorter.js" type="text/javascript"></script>6) We need to type the HTML markup, the HTML table and its columns <body>    <form id="form1" runat="server">    <div>        <h1>Liverpool Legends</h1>        <table style="width: 50%;" border="1" cellpadding="10" cellspacing ="10" class="liverpool">            <thead>                <tr><th>Defenders</th><th>MidFielders</th><th>Strikers</th></tr>            </thead>            <tbody>            <tr>                <td>Alan Hansen</td>                <td>Graeme Souness</td>                <td>Ian Rush</td>            </tr>            <tr>                <td>Alan Kennedy</td>                <td>Steven Gerrard</td>                <td>Michael Owen</td>            </tr>            <tr>                <td>Jamie Garragher</td>                <td>Kenny Dalglish</td>                <td>Robbie Fowler</td>            </tr>            <tr>                <td>Rob Jones</td>                <td>Xabi Alonso</td>                <td>Dirk Kuyt</td>            </tr>                </tbody>        </table>            </div>    </form></body> 7) Inside the head section we also write the simple JQuery code.   <script type="text/javascript"> $(document).ready(function() { $('.liverpool').tablesorter(); }); </script> 8) Run your application.This is how the HTML table looks before the table is sorted on the basis of the selected column.   9) Now I will click on the Midfielders header.Have a look at the picture below  Tablesorter is an excellent JQuery plugin that makes sorting HTML tables a piece of cake. Hope it helps!!!

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  • How to Plug a Small Hole in NetBeans JSF (Join Table) Code Generation

    - by MarkH
    I was asked recently to provide an assist with designing and building a small-but-vital application that had at its heart some basic CRUD (Create, Read, Update, & Delete) functionality, built upon an Oracle database, to be accessible from various locations. Working from the stated requirements, I fleshed out the basic application and database designs and, once validated, set out to complete the first iteration for review. Using SQL Developer, I created the requisite tables, indices, and sequences for our first run. One of the tables was a many-to-many join table with three fields: one a primary key for that table, the other two being primary keys for the other tables, represented as foreign keys in the join table. Here is a simplified example of the trio of tables: Once the database was in decent shape, I fired up NetBeans to let it have first shot at the code. NetBeans does a great job of generating a mountain of essential code, saving developers what must be millions of hours of effort each year by building a basic foundation with a few clicks and keystrokes. Lest you think it (or any tool) can do everything for you, however, occasionally something tosses a paper clip into the delicate machinery and makes you open things up to fix them. Join tables apparently qualify.  :-) In the case above, the entity class generated for the join table (New Entity Classes from Database) included an embedded object consisting solely of the two foreign key fields as attributes, in addition to an object referencing each one of the "component" tables. The Create page generated (New JSF Pages from Entity Classes) worked well to a point, but when trying to save, we were greeted with an error: Transaction aborted. Hmm. A quick debugger session later and I'd identified the issue: when trying to persist the new join-table object, the embedded "foreign-keys-only" object still had null values for its two (required value) attributes...even though the embedded table objects had populated key attributes. Here's the simple fix: In the join-table controller class, find the public String create() method. It will look something like this:     public String create() {        try {            getFacade().create(current);            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("JoinEntityCreated"));            return prepareCreate();        } catch (Exception e) {            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));            return null;        }    } To restore balance to the force, modify the create() method as follows (changes in red):     public String create() {         try {            // Add the next two lines to resolve:            current.getJoinEntityPK().setTbl1id(current.getTbl1().getId().toBigInteger());            current.getJoinEntityPK().setTbl2id(current.getTbl2().getId().toBigInteger());            getFacade().create(current);            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("JoinEntityCreated"));            return prepareCreate();        } catch (Exception e) {            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));            return null;        }    } I'll be refactoring this code shortly, but for now, it works. Iteration one is complete and being reviewed, and we've met the milestone. Here's to happy endings (and customers)! All the best,Mark

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  • Strange behavior with Powershell scriptblock variable scope and modules, any suggestions?

    - by DanMan
    NOTE: I'm using PowerShell 2.0 on Windows Vista. I'm trying to add support for specifying build arguments to psake, but I've run into some strange PowerShell variable scoping behavior dealing specifically with calling functions that have been exported using Export-ModuleMember (which is how psake exposes it's main method). Following is a simple PowerShell module to illustrate (named repoCase.psm1): function Test { param( [Parameter(Position=0,Mandatory=0)] [scriptblock]$properties = {} ) $defaults = {$message = "Hello, world!"} Write-Host "Before running defaults, message is: $message" . $defaults #At this point, $message is correctly set to "Hellow, world!" Write-Host "Aftering running defaults, message is: $message" . $properties #At this point, I would expect $message to be set to whatever is passed in, #which in this case is "Hello from poperties!", but it isn't. Write-Host "Aftering running properties, message is: $message" } Export-ModuleMember -Function "Test" To test the module, run the following sequence of commands (be sure you're in the same directory as the repoCase.psm1): Import-Module .\repoCase.psm1 #Note that $message should be null Write-Host "Before execution - In global scope, message is: $message" Test -properties { "Executing properties, message is $message"; $message = "Hello from properties!"; } #Now $message is set to the value from the script block. The script block affected only the global scope. Write-Host "After execution - In global scope, message is: $message" Remove-Module repoCase The behavior I expected was for the script block I passed to Test to affect the local scope of Test. It is being 'dotsourced' in, so any changes it makes should be within the scope of the caller. However, that's not what's happening, it seems to be affecting the scope of where it was declared. Here's the output: Before execution - In global scope, message is: Before running defaults, message is: Aftering running defaults, message is: Hello, world! Executing properties, message is Aftering running properties, message is: Hello, world! After execution - In global scope, message is: Hello from properties! Interestingly, if I don't export Test as a module and instead just declare the function and invoke it, everything works just like I would expect it to. The script block affects only Test's scope, and does not modify the global scope. I'm not a PowerShell guru, but can someone explain this behavior to me?

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  • c# - How do you get a variable's name as it was physically typed in its declaration?

    - by Petras
    The class below contains the field city. I need to dynamically determine the field's name as it is typed in the class declaration i.e. I need to get the string "city" from an instance of the object city. I have tried to do this by examining its Type in DoSomething() but can't find it when examining the contents of the Type in the debugger. Is it possible? public class Person { public string city = "New York"; public Person() { } public void DoSomething() { Type t = city.GetType(); string field_name = t.SomeUnkownFunction(); //would return the string "city" if it existed! } } Some people in their answers below have asked me why I want to do this. Here's why. In my real world situation, there is a custom attribute above city. [MyCustomAttribute("param1", "param2", etc)] public string city = "New York"; I need this attribute in other code. To get the attribute, I use reflection. And in the reflection code I need to type the string "city" MyCustomAttribute attr; Type t = typeof(Person); foreach (FieldInfo field in t.GetFields()) { if (field.Name == "city") { //do stuff when we find the field that has the attribute we need } } Now this isn't type safe. If I changed the variable "city" to "workCity" in my field declaration in Person this line would fail unless I knew to update the string if (field.Name == "workCity") //I have to make this change in another file for this to still work, yuk! { } So I am trying to find some way to pass the string to this code without physically typing it. Yes, I could declare it as a string constant in Person (or something like that) but that would still be typing it twice. Phew! That was tough to explain!! Thanks Thanks to all who answered this * a lot*. It sent me on a new path to better understand lambda expressions. And it created a new question.

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  • tcpdf table header in each page

    - by DragoN
    i am using tcpdf to create pdf files with rows of table in the first page of pdf i display some info like : List of table .... and header of table after that i display the rows in table if there much rows it contiunes in the next page without the info [List of table... and header of table] i want to display the header of table only in the next pages here is my code $pdf->SetFont('aefurat', '', 15); $pdf->AddPage('P', 'A4'); $pdf->SetFontSize(17); $pdf->Cell(0, 13, 'List of the Byan Table,'C'); $pdf->SetFont('dejavusans', '', 14); $htmlpersian = 'In / Out List'; $pdf->WriteHTML($htmlpersian, true, 0, true, 0); $pdf->setRTL(false); $pdf->SetFontSize(11); $pdf->setRTL(true); Connect(); $resultsc = mysql_query("SELECT * FROM byan Order By Date "); while($r = mysql_fetch_array($resultsc)) { $printresult .= ' <tr> <td ><center>'.$r['Date'].'</center></td> <td ><center>'.$r['In'].'</center></td> <td ><center>'.$r['Out'].'</center></td> <td ><center>'.$r['Balance'].'</center></td> <td ><center>'.$r['Info'].'</center></td> <td ><center>'.$r['Number'].'</center></td> </tr>'; } $tbl = ' <table cellspacing="0" cellpadding="1" border="1" align="center"> <tr> <td style="width: 13%; background-color:black; color:white;"><center>Date</center></td> <td style="width: 11%; background-color:black; color:white;"><center>In</center></td> <td style="width: 11%; background-color:black; color:white;"><center>Out</center></td> <td style="width: 12%; background-color:black; color:white;"><center>Balance</center></td> <td style="width: 45%; background-color:black; color:white;"><center>Info</center></td> <td style="width: 11%; background-color:black; color:white;"><center>Number</center></td> </tr> '.$printresult.' </table> '; $pdf->writeHTML($tbl, true, false, true, false, ''); the output is First Page: List of the Byan Table In / Out List Table Header rows Second Page: Rows Third Page: Rows i want the output to be like that First Page: List of the Byan Table In / Out List Table Header Rows Second Page: Table Header Rows Third Page: Table Header Rows

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  • Joins in single-table queries

    - by Rob Farley
    Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Meine (@sqlity), who has a whole series on joins this month. Good for him – it’s a great topic. In that last post I discussed the fact that we write queries against tables, but that the engine turns it into a plan against indexes. My point wasn’t simply that a table is actually just a Clustered Index (or heap, which I consider just a special type of index), but that data access always happens against indexes – never tables – and we should be thinking about the indexes (specifically the non-clustered ones) when we write our queries. I described the scenario of looking up phone numbers, and how it never really occurs to us that there is a master list of phone numbers, because we think in terms of the useful non-clustered indexes that the phone companies provide us, but anyway – that’s not the point of this post. So a table is metadata. It stores information about the names of columns and their data types. Nullability, default values, constraints, triggers – these are all things that define the table, but the data isn’t stored in the table. The data that a table describes is stored in a heap or clustered index, but it goes further than this. All the useful data is going to live in non-clustered indexes. Remember this. It’s important. Stop thinking about tables, and start thinking about indexes. So let’s think about tables as indexes. This applies even in a world created by someone else, who doesn’t have the best indexes in mind for you. I’m sure you don’t need me to explain Covering Index bit – the fact that if you don’t have sufficient columns “included” in your index, your query plan will either have to do a Lookup, or else it’ll give up using your index and use one that does have everything it needs (even if that means scanning it). If you haven’t seen that before, drop me a line and I’ll run through it with you. Or go and read a post I did a long while ago about the maths involved in that decision. So – what I’m going to tell you is that a Lookup is a join. When I run SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 285; against the AdventureWorks2012 get the following plan: I’m sure you can see the join. Don’t look in the query, it’s not there. But you should be able to see the join in the plan. It’s an Inner Join, implemented by a Nested Loop. It’s pulling data in from the Index Seek, and joining that to the results of a Key Lookup. It clearly is – the QO wouldn’t call it that if it wasn’t really one. It behaves exactly like any other Nested Loop (Inner Join) operator, pulling rows from one side and putting a request in from the other. You wouldn’t have a problem accepting it as a join if the query were slightly different, such as SELECT sod.OrderQty FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail as sod on sod.SalesOrderID = soh.SalesOrderID WHERE soh.SalesPersonID = 285; Amazingly similar, of course. This one is an explicit join, the first example was just as much a join, even thought you didn’t actually ask for one. You need to consider this when you’re thinking about your queries. But it gets more interesting. Consider this query: SELECT SalesOrderID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276 AND CustomerID = 29522; It doesn’t look like there’s a join here either, but look at the plan. That’s not some Lookup in action – that’s a proper Merge Join. The Query Optimizer has worked out that it can get the data it needs by looking in two separate indexes and then doing a Merge Join on the data that it gets. Both indexes used are ordered by the column that’s indexed (one on SalesPersonID, one on CustomerID), and then by the CIX key SalesOrderID. Just like when you seek in the phone book to Farley, the Farleys you have are ordered by FirstName, these seek operations return the data ordered by the next field. This order is SalesOrderID, even though you didn’t explicitly put that column in the index definition. The result is two datasets that are ordered by SalesOrderID, making them very mergeable. Another example is the simple query SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276; This one prefers a Hash Match to a standard lookup even! This isn’t just ordinary index intersection, this is something else again! Just like before, we could imagine it better with two whole tables, but we shouldn’t try to distinguish between joining two tables and joining two indexes. The Query Optimizer can see (using basic maths) that it’s worth doing these particular operations using these two less-than-ideal indexes (because of course, the best indexese would be on both columns – a composite such as (SalesPersonID, CustomerID – and it would have the SalesOrderID column as part of it as the CIX key still). You need to think like this too. Not in terms of excusing single-column indexes like the ones in AdventureWorks2012, but in terms of having a picture about how you’d like your queries to run. If you start to think about what data you need, where it’s coming from, and how it’s going to be used, then you will almost certainly write better queries. …and yes, this would include when you’re dealing with regular joins across multiples, not just against joins within single table queries.

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  • Configuration data: single-row table vs. name-value-pair table

    - by Heinzi
    Let's say you write an application that can be configured by the user. For storing this "configuration data" into a database, two patterns are commonly used. The single-row table CompanyName | StartFullScreen | RefreshSeconds | ... ---------------+-------------------+------------------+-------- ACME Inc. | true | 20 | ... The name-value-pair table ConfigOption | Value -----------------+------------- CompanyName | ACME Inc. StartFullScreen | true (or 1, or Y, ...) RefreshSeconds | 20 ... | ... I've seen both options in the wild, and both have obvious advantages and disadvantages, for example: The single-row tables limits the number of configuration options you can have (since the number of columns in a row is usually limited). Every additional configuration option requires a DB schema change. In a name-value-pair table everything is "stringly typed" (you have to encode/decode your Boolean/Date/etc. parameters). (many more) Is there some consensus within the development community about which option is preferable?

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  • Learning PostgreSql: old versions of rows are stored right in the table

    - by Alexander Kuznetsov
    PostgreSql features multi-version concurrency control aka MVCC. To implement MVCC, old versions of rows are stored right in the same table, and this is very different from what SQL Server does, and it leads to some very interesting consequences. Let us play with this thing a little bit, but first we need to set up some test data. Setting up. First of all, let us create a numbers table. Any production database must have it anyway: CREATE TABLE Numbers ( i INTEGER ); INSERT INTO Numbers ( i ) VALUES...(read more)

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  • Use alpha or opacity on a table row using CSS [migrated]

    - by mserin
    I have a CSS stylesheet for a webpage. The webpage has a table with a background color of white (set in the rows, not the table). I would like to set the opacity or alpha to 50%. I have tried so many variations, but come up with no luck. A typical row in the HTML file is: <tr> <td>&nbsp;</td> <td>Twitter</td> </tr> The CSS settings for table rows (which works perfectly) is: tr { font-family: Arial, Helvetica, sans-serif; background:rgb(255,255,255); } To get the alpha, I tried tr { font-family: Arial, Helvetica, sans-serif; background-color:rgba(255,255,255,0.5); } I have also tried background-color-opacity: 0.5; Any other suggestions?

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  • What happened to HTML table tags?

    - by John
    I started to code HTML in 1998, and in that time I was used to code a lot table tags, playing with tr and td, I learned many things analysing the source code of many portals on the internet with notepad and Microsoft FrontPage, the latter, aw, how many tables overlapping others, it was fun, I loved that time. However, I abandoned web programming for almost seven years and this year I decided to see what's the web programming today likes. Completely different, there are not table tags anymore, it's full of div and span tags. Why happened ? What are these new tags and why nobody codes in table tags anymore ?

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  • SQL SERVER – Check If Column Exists in SQL Server Table

    - by Pinal Dave
    A very frequent task among SQL developers is to check if any specific column exists in the database table or not. Based on the output developers perform various tasks. Here are couple of simple tricks which you can use to check if column exists in your database table or not. Method 1 IF EXISTS(SELECT * FROM sys.columns WHERE Name = N'columnName' AND OBJECT_ID = OBJECT_ID(N'tableName')) BEGIN PRINT 'Your Column Exists' END   For AdventureWorks sample database IF EXISTS(SELECT * FROM sys.columns WHERE Name = N'Name' AND OBJECT_ID = OBJECT_ID(N'[HumanResources].[Department]')) BEGIN PRINT 'Your Column Exists' END   Method 2 IF COL_LENGTH('table_name','column_name') IS NOT NULL BEGIN PRINT 'Your Column Exists' END For AdventureWorks sample database IF COL_LENGTH('[HumanResources].[Department]','Name') IS NOT NULL BEGIN PRINT 'Your Column Exists' END Method 3 IF EXISTS( SELECT TOP 1 * FROM INFORMATION_SCHEMA.COLUMNS WHERE [TABLE_NAME] = 'TableName' AND [COLUMN_NAME] = 'ColumnName' AND [TABLE_SCHEMA] = 'SchemaName') BEGIN PRINT 'Your Column Exists' END For AdventureWorks sample database IF EXISTS( SELECT TOP 1 * FROM INFORMATION_SCHEMA.COLUMNS WHERE [TABLE_NAME] = 'Department' AND [COLUMN_NAME] = 'Name' AND [TABLE_SCHEMA] = 'HumanResources') BEGIN PRINT 'Your Column Exists' END Let me know if you know any other method to find if Column Exists in SQL Server Table. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • sorting dynamic table created by form inputs [migrated]

    - by mille
    i am having problems with sorting can someone help to sort this table not just by its form entry id but onclick with some other columns i tried a lot of plugins but cant get anything to work and i dont know what to do i am new at this i sorry for my english thanks. here is the js: var Animals ={ index: window.localStorage.getItem("Animals:index"), $table: document.getElementById("animals-table"), $form: document.getElementById("animals-form"), $button_save: document.getElementById("animals-save"), $button_discard: document.getElementById("animals-discard"), init: function() { if (!Animals.index) { window.localStorage.setItem("Animals:index", Animals.index = 1); } Animals.$form.reset(); Animals.$button_discard.addEventListener("click", function(event) { Animals.$form.reset(); Animals.$form.id_entry.value = 0; }, true); Animals.$form.addEventListener("submit", function(event) { var entry = { id: parseInt(this.id_entry.value), animal_id:this.animal_id.value, animal_name: this.animal_name.value, animal_type: this.animal_type.value, bday: this.bday.value, animal_sex: this.animal_sex.value, mother_name: this.mother_name.value, farm_name: this.farm_name.value, money: this.money.value, weight: this.weight.value, purchase_partner: this.purchase_partner.value }; if (entry.id === 0) { Animals.storeAdd(entry); Animals.tableAdd(entry); } else { // edit Animals.storeEdit(entry); Animals.tableEdit(entry); } this.reset(); this.id_entry.value = 0; event.preventDefault(); }, true); if (window.localStorage.length - 1) { var animals_list = [], i, key; for (i = 0; i < window.localStorage.length; i++) { key = window.localStorage.key(i); if (/Animals:\d+/.test(key)) { animals_list.push(JSON.parse(window.localStorage.getItem(key))); } } if (animals_list.length) { animals_list.sort(function(a, b) {return a.id < b.id ? -1 : (a.id > b.id ? 1 : 0);}) .forEach(Animals.tableAdd);} Animals.$table.addEventListener("click", function(event) { var op = event.target.getAttribute("data-op"); if (/edit|remove/.test(op)) { var entry = JSON.parse(window.localStorage.getItem("Animals:"+ event.target.getAttribute("data- id"))); if (op == "edit") { Animals.$form.id_entry.value = entry.id; Animals.$form.animal_id.value = entry.animal_id; Animals.$form.animal_name.value = entry.animal_name; Animals.$form.animal_type.value = entry.animal_type; Animals.$form.bday.value = entry.bday; Animals.$form.animal_sex.value = entry.animal_sex; Animals.$form.mother_name.value = entry.mother_name; Animals.$form.farm_name.value = entry.farm_name; Animals.$form.money.value = entry.money; Animals.$form.weight.value = entry.weight; Animals.$form.purchase_partner.value = entry.purchase_partner; } else if (op == "remove") { if (confirm('Are you sure you want to remove this animal from your list?' )) { Animals.storeRemove(entry); Animals.tableRemove(entry); } } event.preventDefault(); } }, true); }, storeAdd: function(entry) { entry.id = Animals.index; window.localStorage.setItem("Animals:index", ++Animals.index); window.localStorage.setItem("Animals:"+ entry.id, JSON.stringify(entry)); }, storeEdit: function(entry) { window.localStorage.setItem("Animals:"+ entry.id, JSON.stringify(entry)); }, storeRemove: function(entry) { window.localStorage.removeItem("Animals:"+ entry.id); }, tableAdd: function(entry) { var $tr = document.createElement("tr"), $td, key; for (key in entry) { if (entry.hasOwnProperty(key)) { $td = document.createElement("td"); $td.appendChild(document.createTextNode(entry[key])); $tr.appendChild($td); } } $td = document.createElement("td"); $td.innerHTML = '<a data-op="edit" data-id="'+ entry.id +'">Edit</a> | <a data-op="remove" data-id="'+ entry.id +'">Remove</a>'; $tr.appendChild($td); $tr.setAttribute("id", "entry-"+ entry.id); Animals.$table.appendChild($tr); }, tableEdit: function(entry) { var $tr = document.getElementById("entry-"+ entry.id), $td, key; $tr.innerHTML = ""; for (key in entry) { if (entry.hasOwnProperty(key)) { $td = document.createElement("td"); $td.appendChild(document.createTextNode(entry[key])); $tr.appendChild($td); } } $td = document.createElement("td"); $td.innerHTML = '<a data-op="edit" data-id="'+ entry.id +'">Edit</a> | <a data-op="remove" data-id="'+ entry.id +'">Remove</a>'; $tr.appendChild($td); }, tableRemove: function(entry) { Animals.$table.removeChild(document.getElementById("entry-"+ entry.id)); } }; Animals.init();

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