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• SQL query select from table and group on other column...

  - by scaryjones

  I'm phrasing the question title poorly as I'm not sure what to call what I'm trying to do but it really should be simple. I've a link / join table with two ID columns. I want to run a check before saving new rows to the table. The user can save attributes through a webpage but I need to check that the same combination doesn't exist before saving it. With one record it's easy as obviously you just check if that attributeId is already in the table, if it is don't allow them to save it again. However, if the user chooses a combination of that attribute and another one then they should be allowed to save it. Here's an image of what I mean: So if a user now tried to save an attribute with ID of 1 it will stop them, but I need it to also stop them if they tried ID's of 1, 10 so long as both 1 and 10 had the same productAttributeId. I'm confusing this in my explanation but I'm hoping the image will clarify what I need to do. This should be simple so I presume I'm missing something.

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• Lucene Search Returning Extra, Undesired Records

  - by Brandon

  I have a Lucene index that contains a field called 'Name'. I escape all special characters before inserting a value into my index using QueryParser.Escape(value). In my example I have 2 documents with the following names respectively: Test Test (Test) They get inserted into my index as such (I can confirm this using Luke): [test] [test] [\(test\)] I insert these values as TOKENIZED and using the StandardAnalyzer. When I perform a search, I use the QueryParser.Escape(searchString) against my search string input to escape special characters and then use the QueryParser with my 'Name' field and the StandardAnalyzer to perform my search. When I perform a search for 'Test', I get back both documents in my index (as expected). However, when I perform a search for 'Test (Test)', I am getting back both documents still. I realize that in both examples it matches on the 'test' term in the index, but I am confused in my 2nd example why it would not just pull back the document with the value of 'Test (Test)' because my search should create two terms: [test] and [\(test\)] I would imagine it would perform some sort of boolean operator where BOTH terms must match in that situation so I would get back just one record. Is there something I am missing or a trick to make the search behave as desired?

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• Is there a way to identify that a file has been modified and moved?

  - by Eric

  I'm writing an application that catalogs files, and attributes them with extra meta data through separate "side-car" files. If changes to the files are made through my program then it is able to keep everything in sync between them and their corresponding meta data files. However, I'm trying to figure out a way to deal with someone modifying the files manually while my program is not running. When my program starts up it scans the file system and compares the files it finds to it's previous record of what files it remembers being there. It's fairly straight forward to update after a file has been deleted or added. However, if a file was moved or renamed then my program sees that as the old file being deleted, and the new file being added. Yet I don't want to loose the association between the file and its metadata. I was thinking I could store a hash from each file so I could check to see if newly found files were really previously known files that had been moved or renamed. However, if the file is both moved/renamed and modified then the hash would not match either. So is there some other unique identifier of a file that I can track which stays with it even after it is renamed, moved, or modified?

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• How do you create a generic method in a class?

  - by Seth Spearman

  Hello, I am really trying to follow the DRY principle. I have a sub that looks like this? Private Sub DoSupplyModel OutputLine("ITEM SUMMARIES") Dim ItemSumms As New SupplyModel.ItemSummaries(_currentSupplyModel, _excelRows) ItemSumms.FillRows() OutputLine("") OutputLine("NUMBERED INVENTORIES") Dim numInvs As New SupplyModel.NumberedInventories(_currentSupplyModel, _excelRows) numInvs.FillRows() OutputLine("") End Sub I would like to collapse these into a single method using generics. For the record, ItemSummaries and NumberedInventories are both derived from the same base class DataBuilderBase. I can't figure out the syntax that will allow me to do ItemSumms.FillRows and numInvs.FillRows in the method. FillRows is declared as Public Overridable Sub FillRows in the base class. Thanks in advance. EDIT Here is my end result Private Sub DoSupplyModels() DoSupplyModelType("ITEM SUMMARIES",New DataBlocks(_currentSupplyModel,_excelRows) DoSupplyModelType("DATA BLOCKS",New DataBlocks(_currentSupplyModel,_excelRows) End Sub Private Sub DoSupplyModelType(ByVal outputDescription As String, ByVal type As DataBuilderBase) OutputLine(outputDescription) type.FillRows() OutputLine("") End Sub But to answer my own question...I could have done this... Private Sub DoSupplyModels() DoSupplyModelType(Of Projections)("ITEM SUMMARIES") DoSupplyModelType(Of DataBlocks)("DATA BLOCKS") End Sub Private Sub DoSupplyModelType(Of T as DataBuilderBase)(ByVal outputDescription As String, ByVal type As T) OutputLine(outputDescription) dim type as New T(_currentSupplyModel,_excelRows) type.FillRows() OutputLine("") End Sub Is that right? Does the New T() work? Seth

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• Return the Column Name for row with last non-null value "Ms Access 2007"

  - by bri1969

  I have a Table, which contains a list of league players. Each season, we record their Points per Dart. Their total PPD for that season is stored in other tables and extracted through other queries, which in turn are imported to the master table "Player History" at the end of the season for use as historical data. The current query retrieves each players PPD for each season they played, when they played last, and how many seasons played. The code for Last season Played has become too long and unstable to use. it was originally created, and split into two separate columns because a single SQL was to long. (LSP1) and LSP2) which work, but as I add seasons, Access does not like the length of code. In short, i need to find a more simple code that will look at each row, and look in that row for the last non null cell and report which column that last non null value is in. So if a player played seasons 30 & 31, but did not play 32..but did play 33, the Column with the code should be titled Last Season Played, and for that Player, it would state "33" in that cell, indicating that this player last played season "33" I will provide both tables and the query.. Please help

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• Difficulty Inserting from HTML form into MySQL (created in Workbench)

  - by Chaya Cooper

  I created a MySQL database in Workbench 5.2.35 for purposes of storing and using information submitted in html forms but I'm having difficulty inserting records from the html form. The relevant SQL script was saved as Demo2.sql, the schema is C2F, and the table is customer_info. I wasn't sure if that was the problem, so I tried replacing the database name (Demo2) with the schema name, but that didn't work either. My html file includes: form action="insert.php" method="post" The insert.php file states: ?php $con = mysql_connect("localhost","root","****"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("Demo2", $con); $sql="INSERT INTO customer_info(fname, lname, user, password, reminder, answer) VALUES ('$_POST[fname]','$_POST[lname]','$_POST[user]','$_POST[password]','$_POST[reminder]','$_POST[answer]')"; if (!mysql_query($sql,$con)) { die('Error: ' . mysql_error()); } echo "1 record added"; mysql_close($con) ? I've also tried INSERT INTO c2f.customer_info(fname, lname, etc. and INSERT INTO 'c2f'.'customer_info'

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• Mysql query, need suggestion or solution

  - by Xi Kam

  Can anyone help me, i have two tables and i need records from both the table //////////////////////////////++ Query 1 ++//////////////////////////////////// SELECT SUM(rec_issued) AS issed, regen_id, YEAR(issue_date) AS iYear, MONTH(issue_date) AS iMonth FROM `view_rec_issued` WHERE `regen_id` = 2 GROUP BY YEAR(issue_date) DESC, MONTH(issue_date) DESC ORDER BY issue_date ASC issed regen_id iYear iMonth 424 2 2011 3 4340 2 2011 4 4235 2 2011 5 10570 2 2012 2 4761 2 2012 3 5000 2 2012 4 3700 2 2012 5 3414 2 2012 6 3700 2 2012 7 2992 2 2012 8 995 2 2012 10 ![Result from Query 1][1] //////////////////////////////++ Query 2 ++//////////////////////////////////// SELECT SUM(total_redem) AS redemed, regen_id, YEAR(redemption_date) AS rYear, MONTH(redemption_date) AS rMonth FROM `recredem_month_wise` WHERE `regen_id` = 2 GROUP BY YEAR(redemption_date) DESC, MONTH(redemption_date) DESC order by redemption_date ASC redemed regen_id rYear rMonth 424 2 2011 3 260 2 2011 4 6523 2 2011 5 1070 2 2011 6 200 2 2011 10 500 2 2011 11 9750 2 2012 2 5000 2 2012 3 5500 2 2012 4 3803 2 2012 5 3700 2 2012 7 3000 2 2012 8 ![Result from Query 2][2] But i want it as - issed regen_id iYear iMonth redemed regen_id rYear rMonth 424 2 2011 3 424 2 2011 3 4340 2 2011 4 260 2 2011 4 4235 2 2011 5 6523 2 2011 5 NULL NULL NULL NULL 1070 2 2011 6 NULL NULL NULL NULL 200 2 2011 10 NULL NULL NULL NULL 500 2 2011 11 10570 2 2012 2 9750 2 2012 2 4761 2 2012 3 5000 2 2012 3 5000 2 2012 4 5500 2 2012 4 3700 2 2012 5 3803 2 2012 5 3414 2 2012 6 NULL NULL NULL NULL 3700 2 2012 7 3700 2 2012 7 2992 2 2012 8 3000 2 2012 8 995 2 2012 10 NULL NULL NULL NULL ![I want this output][3] In these table regen_id is unique and i need data as YEAR and MONTH, if in any table not have the records in perticular month and year it should retrieve zero or null. But in every record year and month should equal like this - iYear = rYear and iMonth = rMonth So we can merge both the fields - No need to show year and month twice iYear and rYear = year iMonth and rMonth = month Thank You Please look at this problem.

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• An Array returned by a model association is not an Array?

  - by Warren

  We have a model association that looks something like this: class Example < ActiveRecord::Base has_many :others, :order => 'others.rank' end The rank column is an integer type. The details of these particular models are not really important though as we have found the same problem with other has_many associations between other models. We have also added to the Enumerable module: module Enumerable def method_missing(name) super unless name.to_s[0..7] == 'collect_' method = name.to_s[8..-1] collect{|element| element.send(method)} end end This adds a collect_id method that we can use to get an array of record ids from an array of ActiveRecord objects. So if we use a normal ActiveRecord find :all, we get a nice array which we can then use collect_id on but if we use Example.others.collect_id, we get NoMethodError: undefined method `collect_id' for #<Class:0x2aaaac0060a0> Example.others.class returns "Array" so is it lying or confused? Our solution thus far has been to use it this way: Example.others.to_a.collect_id This works but this seems a bit strange. Why would you have to do that? We are on Ruby 1.8.7 and Rails 2.3.4

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• MYSQL variables - SET @var

  - by Lizard

  I am attempting to create a mysql snippet that will analyse a table and remove duplicate entries (duplicates are based on two fields not entire record) I have the following code that works when I hard code the variables in the queries, but when I take them out and put them as variables I get mysql errors, below is the script SET @tblname = 'mytable'; SET @fieldname = 'myfield'; SET @concat1 = 'checkfield1'; SET @concat2 = 'checkfield2'; ALTER TABLE @tblname ADD `tmpcheck` VARCHAR( 255 ) NOT NULL; UPDATE @tblname SET `tmpcheck` = CONCAT(@concat1,'-',@concat2); CREATE TEMPORARY TABLE `tmp_table` ( `tmpfield` VARCHAR( 100 ) NOT NULL ) ENGINE = MYISAM ; INSERT INTO `tmp_table` (`tmpfield`) SELECT @fieldname FROM @tblname GROUP BY `tmpcheck` HAVING ( COUNT(`tmpcheck`) > 1 ); DELETE FROM @tblname WHERE @fieldname IN (SELECT `tmpfield` FROM `tmp_table`); ALTER TABLE @tblname DROP `tmpcheck`; I am getting the following error: #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@tblname ADD `tmpcheck` VARCHAR( 255 ) NOT NULL' at line 1 Is this because I can't use a variable for a table name? What else could be wrong or how wopuld I get around this issue. Thanks in adavnce

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• Convert one delphi code line to c++

  - by user1332636

  How can I write that line in c++? This is the code in delphi type TSettings = record sFileName: String[50]; siInstallFolder: Byte; bRunFile: Boolean; ... end; .. var i: dword; sZdData: PChar; Settings :Tsettings; begin .... ZeroMemory(@Settings, sizeof(Tsettings)); settings := Tsettings(Pointer(@sZdData[i])^); // this code to c++ c++ code (hope the rest is OK) struct TSettings{ char sFileName[50]; byte siInstallFolder; bool bRunFile; ... } Settings; ... DWORD i; LPBYTE sZdData; ZeroMemory(&Settings, sizeof(TSettings)); Settings = ????? // im failing here i dunno what to do // i need same as in delphi code above

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• Error while saving csv file generated by PHP

  - by user1667374

  I have created below script which is saving the csv file in the same path of this script but when I am saving it to different directory, it gives me error. Can somebody please help me on this? This is the error: Warning: fopen(/store/secure/mas/) [function.fopen]: failed to open stream: No such file or directory in /getdetails.php on line 15 Warning: fputs(): supplied argument is not a valid stream resource in /getdetails.php on line 36 Warning: fclose(): supplied argument is not a valid stream resource in /getdetails.php on line 39 This is the script: <?php $MYSQL_HOST="localhost"; $MYSQL_USERNAME="***"; $MYSQL_PASSWORD="***"; $MYSQL_DATABASE="shop"; $MYSQL_TABLE="ds_orders"; mysql_connect( "$MYSQL_HOST", "$MYSQL_USERNAME", "$MYSQL_PASSWORD" ) or die( mysql_error( ) ); mysql_select_db( "$MYSQL_DATABASE") or die( mysql_error( $conn ) ); $filename="Order_Details"; $directory = "/store/secure/mas/"; $csv_filename = $filename.".csv"; $fd = fopen ( "$directory" . $cvs_filename, "w"); $today="2009-03-17"; $disp_date="05122008"; $sql = "SELECT * FROM $MYSQL_TABLE where cDate='$today'"; $result=mysql_query($sql); $rows=mysql_num_rows($result); echo $rows; if(mysql_num_rows($result)>0){ $fileContent="Record ID,Discount Percent\n"; while($data=mysql_fetch_array($result)) { $fileContent.= "".$data['oID'].",".$data['discount']."\n"; } $fileContent=str_replace("\n\n","\n",$fileContent); fputs($fd, $fileContent); } fclose($fd); ?>

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• jQuery toggle() with unknown initial state

  - by Jason Morhardt

  I have a project that I am working on that uses a little image to mark a record as a favorite on multiple rows in a table. The data gets pulled from a DB and the image is based on whether or not that item is a favorite. One image for a favorite, a different image if not a favorite. I want the user to be able to toggle the image and make it a favorite or not. Here's my code: $(function () { $('.FavoriteToggle').toggle( function () { $(this).find("img").attr({src:"../../images/icons/favorite.png"}); var ListText = $(this).find('.FavoriteToggleIcon').attr("title"); var ListID = ListText.match(/\d+/); $.ajax({ url: "include/AJAX.inc.php", type: "GET", data: "action=favorite&ItemType=0&ItemID=" + ListID, success: function () {} }); }, function () { $(this).find("img").attr({src:"../../images/icons/favorite_not.png"}); var ListText = $(this).find('.FavoriteToggleIcon').attr("title"); var ListID = ListText.match(/\d+/); $.ajax({ url: "include/AJAX.inc.php", type: "GET", data: "action=favorite&ItemType=0&ItemID=" + ListID, success: function () {} }); } ); }); Works great if the initial state is not a favorite. But you have to double click to get the image to change if it IS a favorite initially. This causes the AJAX to fire twice and essentially make it a favorite then not a favorite before the image responds. The user thinks he's made it a favorite because the image changed, but in fact, it's not. Help anybody?

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• memory management: am i doing something wrong here?

  - by z s

  Hi, In a very small number of cases in my iphone app, I get a crash after the for loop in the code below: ABAddressBookRef addressBookInit = ABAddressBookCreate(); CFMutableArrayRef abContacts = (CFMutableArrayRef)ABAddressBookCopyArrayOfAllPeople(addressBookInit); // get array of all contacts CFArraySortValues (abContacts, CFRangeMake(0, CFArrayGetCount(abContacts)), (CFComparatorFunction)ABPersonComparePeopleByName, (void *)ABPersonGetSortOrdering()); NSArray *copypeople = (NSArray *) abContacts; NSMutableArray *tempTheadlist = [[NSMutableArray alloc] init]; for (int i=0; i < copypeople.count; i++) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; ABRecordRef record = [copypeople objectAtIndex:i]; if (blah blah) [tempThreadList addObject: someObject]; [pool release]; } // POINT OF CRASH AFTER LOOP ENDS if (tempTheadlist.count > 0) [NSThread detachNewThreadSelector: @selector(loading_pictures:) toTarget:self withObject:tempTheadlist]; [tempTheadlist release]; [copypeople release]; CFRelease(addressBookInit); Any reason why it should crash at any point here?

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• implementing user tracking (logging) in Rails 3

  - by seth.vargo

  Hi, I'm creating a Rails application in which logging individual user actions is vital. Every time a user clicks a url, I want to log the action along with all parameters. Here is my current implementation: class CreateActivityLogs < ActiveRecord::Migration create_table :activity_logs do |t| t.references :user t.string :ip_address t.string :referring_url t.string :current_url t.text :params t.text :action t.timestamps end end   class ActivityLog < ActiveRecord::Base belongs_to :user end In a controller, I'd like to be able to do something like the following: ... ActivityLog::log @user.id, params, 'did foo with bar' ... I'd like to have the ActivityLog::log method automatically get the IP address, referring url, and current url (I know how to do this already) and create a new record in the table. So, my questions are: How do I do this? How do I use ActivityLog without having to create an instance everytime I want to log? Is this the best way? Some people have argued for a flat-file log for this kind of logging - however, I want admins to be able to see a user's activity in the backend as well, so I thought a database solution may be better?

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• PHP is truncating MSSQL Blob data (4096b), even after setting INI values. Am I missing one?

  - by Dutchie432

  I am writing a PHP script that goes through a table and extracts the varbinary(max) blob data from each record into an external file. The code is working perfectly, except when a file is over 4096b - the data is truncated at exactly 4096. I've modified the values for mssql.textlimit, mssql.textsize, and odbc.defaultlrl without any success. Am I missing something here? <?php ini_set("mssql.textlimit" , "2147483647"); ini_set("mssql.textsize" , "2147483647"); ini_set("odbc.defaultlrl", "0"); include_once('common.php'); $id=$_REQUEST['i']; $q = odbc_exec($connect, "Select id,filename,documentBin from Projectdocuments where id = $id"); if (odbc_fetch_row($q)){ echo "Trying $filename ... "; $fileName="projectPhotos/docs/".odbc_result($q,"filename"); if (file_exists($fileName)){ unlink($fileName); } if($fh = fopen($fileName, "wb")) { $binData=odbc_result($q,"documentBin"); fwrite($fh, $binData) ; fclose($fh); $size = filesize($fileName); echo ("$fileName<br />Done ($size)<br><br>"); }else { echo ("$fileName Failed<br>"); } } ?> OUTPUT Trying ... projectPhotos/docs/file1.pdf Done (4096) Trying ... projectPhotos/docs/file2.zip Done (4096) Trying ... projectPhotos/docsv3.pdf Done (4096) etc..

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• How do I select every 6th element from a list (using Linq)

  - by iDog

  Hi, I've got a list of 'double' values. I need to select every 6th record. It's a list of coordinates, where I need to get the minimum and maximum value of every 6th value. List of coordinates (sample): [2.1, 4.3, 1.0, 7.1, 10.6, 39.23, 0.5, ... ] with hundrets of coordinates. Result should look like: [x_min, y_min, z_min, x_max, y_max, z_max] with exactly 6 coordinates. Following code works, but it takes to long to iterate over all coordinates. I'd like to use Linq instead (maybe faster?) for (int i = 0; i < 6; i++) { List<double> coordinateRange = new List<double>(); for (int j = i; j < allCoordinates.Count(); j = j + 6) coordinateRange.Add(allCoordinates[j]); if (i < 3) boundingBox.Add(coordinateRange.Min()); else boundingBox.Add(coordinateRange.Max()); } Any suggestions? Many thanks! Greets!

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• Abstract away a compound identity value for use in business logic?

  - by John K

  While separating business logic and data access logic into two different assemblies, I want to abstract away the concept of identity so that the business logic deals with one consistent identity without having to understand its actual representation in the data source. I've been calling this a compound identity abstraction. Data sources in this project are swappable and various and the business logic shouldn't care which data source is currently in use. The identity is the toughest part because its implementation can change per kind of data source, whereas other fields like name, address, etc are consistently scalar values. What I'm searching for is a good way to abstract the concept of identity, whether it be an existing library, a software pattern or just a solid good idea of some kind is provided. The proposed compound identity value would have to be comparable and usable in the business logic and passed back to the data source to specify records, entities and/or documents to affect, so the data source must be able to parse back out the details of its own compound ids. Data Source Examples: This serves to provide an idea of what I mean by various data sources having different identity implementations. A relational data source might express a piece of content with an integer identifier plus a language specific code. For example. content_id language Other Columns expressing details of content 1 en_us 1 fr_ca The identity of the first record in the above example is: 1 + en_us However when a NoSQL data source is substituted, it might somehow represent each piece of content with a GUID string 936DA01F-9ABD-4d9d-80C7-02AF85C822A8 plus language code of a different standardization, And a third kind of data source might use just a simple scalar value. So on and so forth, you get the idea.

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• Ways to prevent multiple email notification with php&mysql

  - by Louis Loudog Trottier

  My 1st post, but i got many great answers and tips from stackoverflow so far. This one was a close call- How does facebook, gmail send the real time notification? but not exactly, so let brainstorm this together. I have CMS system with mail notification when a change is made on the site. Everything wotk very well but i want to prevent multiple notification if somene make another quick change to, let say, fix a typo. Using php mail(), obviously. I've tough of 2 ways, one simple, and one.... let just say, pretty heavy... cough. the 3rd one was inspired by Implementing Email Notification but really doesn't look appealing to me to send bunch of email at once. Use a timestamp to check if another change was made in the 'let say' last 5 minutes. Record the last change, and compare it to the new one. Could be usefull for backup at the same time since i'll have to save the change somewhere, but text can be long and making an sql search would be painfull. Wouldn't it? Use cron to send changes every x minutes... convince me if you ythink it is a suitable solution. Any ideas, comment or suggestion of your own? Looking forward for your inputs, and since i now registered, i'll do my best to help around. Cheers, all llt

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• Jquery image slider window resize scaling issue

  - by eb_Dev

  Hi, I have created image gallery slider, the images of which scale with the window size. My problem is I can't seem to create the right formula to ensure that the slider is at the right position when the window is scaled. If I am at the first image and the slider 'left' offset is 0 then the scaling works fine and my offset is correct, however when I am on image two and my slider is offset by say -1500 and then the window is resized, the slider is then at the wrong offset. Taking this into account I figured I could just add / subtract the new window size difference from the slider offset and therefore have everything in the right position. I was wrong. It works for the first two images but then If I am at the end of my slider on the last image I get a nice big gap between the end of the last image and the border of the page. Can someone please show my where I am going wrong please? I've spent days on this :( The relevant code is as follows: $(window).bind('resize', function(event, delta) { /* Resize work images - resizes all to document width */ resizeWorkImages('div.page.work div#work ul'); /* Position slider controls */ positionSliderControls(); /* Get the difference between the old window width and the new */ var windowDiff = (gLastWindowWidth - $(window).width()) * -1; /* Apply difference to slider left position */ var newSliderLeftPos = stripPx($('div.page.work div#work ul').css('left')) - windowDiff; /* Apply to slider */ $('div.page.work div#work ul').css('left',newSliderLeftPos+'px') /* Update gSlider settings */ gSlider.update(); /* Record new window width */ gLastWindowWidth = $(window).width(); }); Thanks, eb_dev

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• Cryptography for P2P card game

  - by zephyr

  I'm considering writing a computer adaptation of a semi-popular card game. I'd like to make it function without a central server, and I'm trying to come up with a scheme that will make cheating impossible without having to trust the client. The basic problem as I see it is that each player has a several piles of cards (draw deck, current hand and discard deck). It must be impossible for either player to alter the composition of these piles except when allowed by the game rules (ie drawing or discarding cards), nor should players be able to know what is in their or their oppponent's piles. I feel like there should be some way to use something like public-key cryptography to accomplish this, but I keep finding holes in my schemes. Can anyone suggest a protocol or point me to some resources on this topic? [Edit] Ok, so I've been thinking about this a bit more, and here's an idea I've come up with. If you can poke any holes in it please let me know. At shuffle time, a player has a stack of cards whose value is known to them. They take these values, concatenate a random salt to each, then hash them. They record the salts, and pass the hashes to their opponent. The opponent concatenates a salt of their own, hashes again, then shuffles the hashes and passes the deck back to the original player. I believe at this point, the deck has been randomized and neither player can have any knowledge of the values. However, when a card is drawn, the opponent can reveal their salt, allowing the first player to determine what the original value is, and when the card is played the player reveals their own salt, allowing the opponent to verify the card value.

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• Scheme Homework Assignment

  - by user1704677

  In a course I am taking we recently had to learn the programming language Scheme. I get all of the basics, which is pretty much all that we have gone though. I'm just having trouble learning to think in the different way that Scheme consists of. I was given an assignment and really do not even know how to start. I have sat here for a few hours trying to figure out how to even get started, but I'm kind of stumped. For the record, I'm not asking for the code to solve this problem, but more of some thoughts to get me on the right track. Anyway, here is the gist of the assignment... We are given a list of ten numbers that represent a voter's votes. The numbers are -1, 0 or 1. Then we are given a list of lists of Candidates, with a name and then ten numbers corresponding to that candidate's votes. These numbers are also -1 0 and 1. So for example. '(0 0 0 -1 -1 1 0 1 0 -1) '(Adams 0 1 -1 0 1 1 0 -1 -1 0 0) We are asked to implement a function called best_candidates that will take in a list of numbers (Voter) and a list of lists of Candidates. Then we have to compare the votes of the voter against the list of each candidate and return a list of names with the most common votes. So far, I've come up with a few things. I'm just confused on how I will check the values and retain the name of the voter? I guess I'm still stuck in thinking C/Java and it's making this very tough. Any suggestions to help get me started?

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• rails route question

  - by badnaam

  I am trying to build a search functionality which at a high level works like this. 1 - I have a Search model, controller with a search_set action and search views/partial to render the search. 2 - At the home page a serach form is loaded with an empty search object or a search object initialized with session[:search] (which contains user search preferences, zip code, proximity, sort order, per page etc). This form has a post(:put) action to search_set. 3 - When a registered user performs a set the params of the search form are collected and a search record is saved against that user. If a unregistered user performs a search then the search set action simply stores the params in the session[:search]. In either case, the search is executed with the given params and the results are displayed. At this point the url of in the location bar is something like.. http://localhost:3000/searches/search_set?stype=1 At this point if the user simply hits enter on the location bar, I get an error that says "No action responded to show" I am guessing because the URL contains search_set which uses a put method and even though I have a search_show (:get) action (which simply reruns the search in the session or saved in the database) does not get called. How can I handle this situation where I can route a user hitting enter into the location bar to a get method? If this does not explain the problem , please let me know I can share more details/code etc. Thanks!

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• Can't grab foreign key during after_create callback because it doesn't exist yet!

  - by Randy

  I have some models all linked together in memory (parent:child:child:child) and saved at the same time by saving the top-most parent. This works fine. I'd like to tap into the after_create callback of one of the children to populate a changelog table. One of the attributes I need to copy/push into the changelog table is the child's foreign_key to it's direct parent, but it doesn't exist at the time after_create fires!?! Without the after_create callback, I can look in the log and see that the child is being saved before it's parent (foreign key blank) then the parent is inserted... then the child is updated with the id from the parent. The child's after_create is firing at the right time, but it happens before Rails has had a chance to update the child with the foreign_key. Is there any way to force Rails to save such a linkage of models in a certain order? ie.parent, then child (parent foreign_key exists), then that child's child (again, foreign_key is accessible) etc. ?? If not, how would I have my routine fire after a record is created AND get the foreign_key? Seems a callback like this would be helpful: after_create_with_foreign_keys

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• Java using generics with lists and interfaces

  - by MirroredFate

  Ok, so here is my problem: I have a list containing interfaces - List<Interface> a - and a list of interfaces that extend that interface: List<SubInterface> b. I want to set a = b. I do not wish to use addAll() or anything that will cost more memory as what I am doing is already very cost-intensive. I literally need to be able to say a = b. I have tried List<? extends Interface> a, but then I cannot add Interfaces to the list a, only the SubInterfaces. Any suggestions? EDIT I want to be able to do something like this: List<SubRecord> records = new ArrayList<SubRecord>(); //add things to records recordKeeper.myList = records; The class RecordKeeper is the one that contains the list of Interfaces (NOT subInterfaces) public class RecordKeeper{ public List<Record> myList; }

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• MySql: Is it reasonable to use 'view' or I would better denormalize my DB?

  - by Budda

  There is 'team_sector' table with following fields: Id, team_id, sect_id, size, level It contains few records for each 'team' entity (referenced with 'team_id' field). Each record represent sector of team's stadium (totally 8 sectors). Now it is necessary to implement few searches: by overall stadium size (SUM(size)); the best quality (SUM(level)/COUNT(*)). I could create query something like this: SELECT TS.team_id, SUM(TS.size) as OverallSize, SUM(TS.Level)/COUNT(TS.Id) AS QualityLevel FROM team_sector GROUP BY team_id ORDER BY OverallSize DESC / ORDER BY QualityLevel DESC But my concern here is that calculation for each team will be done each time on query performed. It is not too big overhead (at least now), but I would like to avoid performance issues later. I see 2 options here. The 1st one is to create 2 additional fields in 'team' table (for example) and store there OverallSize and QualityLevel fields. If information if 'sector' table is changed - update those table too (probably would be good to do that with triggers, as sector table doesn't change too often). The 2nd option is to create a view that will provide required data. The 2nd option seems much easier for me, but I don't have a lot of experience/knowledge of work with views. Q1: What is the best option from your perspective here and why? Probably you could suggest other options? Q2: Can I create view in such way that it will do calculations rarely (at least once per day)? If yes - how? Q3: Is it reasonable to use triggers for such purpose (1st option). P.S. MySql 5.1 is used, overall number of teams is around 1-2 thousand, overall number of records in sector table - overall 6-8 thousand. I understand, those numbers are pretty small, but I would like to implement the best practice here.

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