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• Dynamic data-entry value store

  - by simendsjo

  I'm creating a data-entry application where users are allowed to create the entry schema. My first version of this just created a single table per entry schema with each entry spanning a single or multiple columns (for complex types) with the appropriate data type. This allowed for "fast" querying (on small datasets as I didn't index all columns) and simple synchronization where the data-entry was distributed on several databases. I'm not quite happy with this solution though; the only positive thing is the simplicity... I can only store a fixed number of columns. I need to create indexes on all columns. I need to recreate the table on schema changes. Some of my key design criterias are: Very fast querying (Using a simple domain specific query language) Writes doesn't have to be fast Many concurrent users Schemas will change often Schemas might contain many thousand columns The data-entries might be distributed and needs syncronization. Preferable MySQL and SQLite - Databases like DB2 and Oracle is out of the question. Using .Net/Mono I've been thinking of a couple of possible designs, but none of them seems like a good choice. Solution 1: Union like table containing a Type column and one nullable column per type. This avoids joins, but will definitly use a lot of space. Solution 2: Key/value store. All values are stored as string and converted when needed. Also use a lot of space, and of course, I hate having to convert everything to string. Solution 3: Use an xml database or store values as xml. Without any experience I would think this is quite slow (at least for the relational model unless there is some very good xpath support). I also would like to avoid an xml database as other parts of the application fits better as a relational model, and being able to join the data is helpful. I cannot help to think that someone has solved (some of) this already, but I'm unable to find anything. Not quite sure what to search for either... I know market research is doing something like this for their questionnaires, but there are few open source implementations, and the ones I've found doesn't quite fit the bill. PSPP has much of the logic I'm thinking of; primitive column types, many columns, many rows, fast querying and merging. Too bad it doesn't work against a database.. And of course... I don't need 99% of the provided functionality, but a lot of stuff not included. I'm not sure this is the right place to ask such a design related question, but I hope someone here has some tips, know of any existing work, or can point me to a better place to ask such a question. Thanks in advance!

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• How can I limit the cache used by copying so there is still memory available for other cache?

  - by Peter

  Basic situation: I am copying some NTFS disks in openSuSE. Each one is 2TB. When I do this, the system runs slow. My guesses: I believe it is likely due to caching. Linux decides to discard useful cache (eg. kde4 bloat, virtual machine disks, LibreOffice binaries, Thunderbird binaries, etc.) and instead fill all available memory (24 GB total) with stuff from the copying disks, which will be read only once, then written and never used again. So then any time I use these apps (or kde4), the disk needs to be read again, and reading the bloat off the disk again makes things freeze/hiccup. Due to the cache being gone and the fact that these bloated applications need lots of cache, this makes the system horribly slow. Since it is USB,the disk and disk controller are not the bottleneck, so using ionice does not make it faster. I believe it is the cache rather than just the motherboard going too slow, because if I stop everything copying, it still runs choppy for a while until it recaches everything. And if I restart the copying, it takes a minute before it is choppy again. But also, I can limit it to around 40 MB/s, and it runs faster again (not because it has the right things cached, but because the motherboard busses have lots of extra bandwidth for the system disks). I can fully accept a performance loss from my motherboard's IO capability being completely consumed (which is 100% used, meaning 0% wasted power which makes me happy), but I can't accept that this caching mechanism performs so terribly in this specific use case. # free total used free shared buffers cached Mem: 24731556 24531876 199680 0 8834056 12998916 -/+ buffers/cache: 2698904 22032652 Swap: 4194300 24764 4169536 I also tried the same thing on Ubuntu, which causes a total system hang instead. ;) And to clarify, I am not asking how to leave memory free for the "system", but for "cache". I know that cache memory is automatically given back to the system when needed, but my problem is that it is not reserved for caching of specific things. Question: Is there some way to tell these copy operations to limit memory usage so some important things remain cached, and therefore any slowdowns are a result of normal disk usage and not rereading the same commonly used files? For example, is there a setting of max memory per process/user/file system allowed to be used as cache/buffers?

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• Special scheduling Algorithm (pattern expansion)

  - by tovare

  Question Do you think genetic algorithms worth trying out for the problem below, or will I hit local-minima issues? I think maybe aspects of the problem is great for a generator / fitness-function style setup. (If you've botched a similar project I would love hear from you, and not do something similar) Thank you for any tips on how to structure things and nail this right. The problem I'm searching a good scheduling algorithm to use for the following real-world problem. I have a sequence with 15 slots like this (The digits may vary from 0 to 20) : 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 (And there are in total 10 different sequences of this type) Each sequence needs to expand into an array, where each slot can take 1 position. 1 1 0 0 1 1 1 0 0 0 1 1 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 0 0 0 1 1 0 0 0 1 1 1 0 0 0 1 1 0 0 1 1 0 0 0 1 1 1 0 0 0 1 1 The constraints on the matrix is that: [row-wise, i.e. horizontally] The number of ones placed, must either be 11 or 111 [row-wise] The distance between two sequences of 1 needs to be a minimum of 00 The sum of each column should match the original array. The number of rows in the matrix should be optimized. The array then needs to allocate one of 4 different matrixes, which may have different number of rows: A, B, C, D A, B, C and D are real-world departments. The load needs to be placed reasonably fair during the course of a 10-day period, not to interfere with other department goals. Each of the matrix is compared with expansion of 10 different original sequences so you have: A1, A2, A3, A4, A5, A6, A7, A8, A9, A10 B1, B2, B3, B4, B5, B6, B7, B8, B9, B10 C1, C2, C3, C4, C5, C6, C7, C8, C9, C10 D1, D2, D3, D4, D5, D6, D7, D8, D9, D10 Certain spots on these may be reserved (Not sure if I should make it just reserved/not reserved or function-based). The reserved spots might be meetings and other events The sum of each row (for instance all the A's) should be approximately the same within 2%. i.e. sum(A1 through A10) should be approximately the same as (B1 through B10) etc. The number of rows can vary, so you have for instance: A1: 5 rows A2: 5 rows A3: 1 row, where that single row could for instance be: 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 etc.. Sub problem* I'de be very happy to solve only part of the problem. For instance being able to input: 1 1 2 3 4 2 2 3 4 2 2 3 3 2 3 And get an appropriate array of sequences with 1's and 0's minimized on the number of rows following th constraints above.

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• Strange behaviour of NSString in NSView

  - by Mee

  Trying to create a Skat-Game, I encountered the following problem: isBidding is a Boolean value indicationg, the program is in a certain state, [desk selected] is a method calling returning the current selected player, chatStrings consists of dictionaries, saving strings with the player, who typed, and what he typed - (void)drawRect:(NSRect)rect { NSMutableDictionary * attributes = [NSMutableDictionary dictionary]; [attributes setObject:[NSFont fontWithName:playerFont size:playerFontSize] forKey:NSFontAttributeName]; [attributes setObject:playerFontColor forKey:NSForegroundColorAttributeName]; [[NSString stringWithFormat:@"Player %i",[desk selected] + 1]drawInRect:playerStringRect withAttributes:attributes]; if (isBidding) { [attributes setObject:[NSFont fontWithName:chatFont size:chatFontSize] forKey:NSFontAttributeName]; [attributes setObject:chatFontColor forKey:NSForegroundColorAttributeName]; int i; for (i = 0; i < [chatStrings count]; i++, yProgress -= 20) { if (isBidding) [[NSString stringWithFormat:@"Player %i bids: %@",[[[chatStrings objectAtIndex:i]valueForKey:@"Player"]intValue], [[chatStrings objectAtIndex:i]valueForKey:@"String"]] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; else [[NSString stringWithFormat:@"Player %i: %@",[[[chatStrings objectAtIndex:i]valueForKey:@"Player"]intValue], [[chatStrings objectAtIndex:i]valueForKey:@"String"]] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; } if (isBidding) [[NSString stringWithFormat:@"Player %i bids: %@",[desk selected] + 1, displayString] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; else [[NSString stringWithFormat:@"Player %i: %@",[desk selected] + 1, displayString] drawAtPoint:NSMakePoint([self bounds].origin.x, yProgress) withAttributes:attributes]; yProgress = chatFontBegin; } } This is the part determining the string's content, the string is contributed by an [event characters] method. -(void)displayChatString:(NSString *)string { displayString = [displayString stringByAppendingString:string]; [self setNeedsDisplay:YES]; } The problem if have is this: when typing in more than two letters the view displays NSRectSet{{{471, 574},{500, 192}}} and returns no more discription when I try to print it. then I get an EXC_BAD_ACCESS message, though I have not released it (as far as I can see) I also created the string with alloc and init, so I cannot be in the autorelease pool. I also tried to watch the process when it changes with the debugger, but I couldn't find any responsible code. As you can see I am still a beginner in Cocoa (and programming in general), so I would be really happy if somebody would help me with this.

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• Create Duplicate Records on SELECT for Calendar Date Range

  - by peterallcdn

  Hey all, I've built a pretty shnazzy calendar system but there is one tweak that I need to make so that I'm completely happy with it. My calendar has three tables: calevents - The calendared event. caldates - The occurrences and date-range of each occurrence for each event. calcats - The categories that can be applied to an event. The short: For each calevent, there can be many caldates, one for each occurrence of calevent. So a calevent that repeats weekly and spans 3 days might have caldates like this: date_id date_eid date_start date_end 2 37 2010-06-21 2010-06-23 3 37 2010-06-28 2010-06-30 7 37 2010-07-05 2010-07-07 9 37 2010-07-12 2010-07-14 What I want to do, is when selecting all the caldates for a specified month such as 2010-06, to return not just the two records above, but instead a record for each date in the range of date_start and date_end for each caldate. So if I searched for 2010-06, I would get: date_id date_eid date_start date_end date_day 2 37 2010-06-21 2010-06-23 2010-06-21 2 37 2010-06-21 2010-06-23 2010-06-22 2 37 2010-06-21 2010-06-23 2010-06-23 3 37 2010-06-28 2010-06-30 2010-06-28 3 37 2010-06-28 2010-06-30 2010-06-29 3 37 2010-06-28 2010-06-30 2010-06-30 The Long: The reason I want to do this, is so when displaying a list of events(calevents) for a specified month, an occurrence(caldates) of that event will be displayed for EACH of the days it spans. I could do this with php by looping through each day of the current month and displaying a copy of each caldate if the month day falls between date_start and date_end. But doing it this way will prevent me from using record pagination if needed. For example, if for a specified month the following caldates were returned: date_id date_eid date_start date_end 2 37 2010-06-21 2010-06-27 94 53 2010-06-09 2010-07-08 Doing record pagination would see this as only 2 records("rows"). But looping through them with PHP would generate 29 "rows". So, I figure if I use mysql to create each row instead of PHP, I can achieve the same thing AND still be able to use pagination if a month has a lot of events/dates. As far as performance goes, I'm not sure which option is more efficient. Both would send the same amount of info to the browser, so it's really only the work required to generate the info that matters. My current query which fetches all the occurrences for a specified month, and to make things just a little more complicated... joins them with their event and category, looks like this: $sql_to_execute = " SELECT date_id, date_eid, date_start, date_end, event_id, event_title, event_category, event_private, event_location, SUBSTRING_INDEX(event_detailsstripped, ' ', 40) AS event_detailsstripped, event_time, event_starttime, event_endtime, event_active, cat_colour FROM ( caldates LEFT JOIN calevents ON caldates.date_eid = calevents.event_id ) LEFT JOIN calcats ON calevents.event_category = calcats.cat_id WHERE date_start <= '".mysql_real_escape_string($dbi_list_end_date)."' AND date_end >= '".mysql_real_escape_string($dbi_list_start_date)."' ".$dbi_category." ORDER BY date_start ASC "; Any help or advice would be greatly appreciated! Thanks, Peter

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• What's the best way to return stuff from a PHP function, and simultaneously trigger a jQuery action?

  - by Jack Webb-Heller

  So the title is a tad ambiguous, but I'll try and give an example. Basically, I have an 'awards' system (similar to that of StackOverflow's badges) in my PHP/CodeIgniter site, and I want, as soon as an award is earned, a notification to appear to the user. Now I'm happy to have this appear on the next page load, but, ideally I'd like it to appear as soon as the award is transactioned since my site is mostly Ajax-powered and there may not be page reloads very often. The way the system works currently, is: 1) If the user does something to trigger the earning of an award, CodeIgniter does this: $params['user_id'] = $this->tank_auth->get_user_id(); $params['award_id'] = 1; // (I have a database table with different awards in) $this->awards->award($params); 2) My custom library, $this->awards, runs the award function: function award($params) { $sql = $this->ci->db->query("INSERT INTO users_awards (user_id, award_id) VALUES ('".$params['user_id']."','".$params['award_id']."') ON DUPLICATE KEY UPDATE duplicate=duplicate+1"); $awardinfo = $this->ci->db->query("SELECT * FROM awards WHERE id = ".$params['award_id']); // If it's the 'first time' the user has gotten the award (e.g. they've earnt it) if ($awardinfo->row('duplicate') == 0) { $params['title'] = $awardinfo->row('title'); $params['description'] = $awardinfo->row('description'); $params['iconpath'] = $awardinfo->row('iconpath'); $params['percentage'] = $awardinfo->row('percentage'); return $params; } } So, it awards the user (and if they've earnt it twice, updates a useless duplicate field by one), then checks if it's the first time they've earnt it (so it can alert them of the award). If so, it gets the variables (title of the award, the award description, the path to an icon to display for the award, and finally the percentage of users who have also got this award) and returns them as an array. So... that's that. Now I'd like to know, what's the best way to do this? Currently my Award-giving bit is called from a controller, but I guess if I want this to trigger via Ajax, then the code should be placed in a View file...? To sum it up: I need the returned award data to appear without a page refresh. What's the best way of doing this? (I'm already using jQuery on my page). Thanks very much everybody! Jack

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• Correct way to make datasources/resources a deploy-time setting

  - by Draemon

  I have a web-app that requires two settings: A JDBC datasource A string token I desperately want to be able to deploy one .war to various different containers (jetty,tomcat,gf3 minimum) and configure these settings at application level within the container. My code does this: InitialContext ctx = new InitialContext(); Context envCtx = (javax.naming.Context) ctx.lookup("java:comp/env"); token = (String)envCtx.lookup("token"); ds = (DataSource)envCtx.lookup("jdbc/datasource") Let's assume I've used the glassfish management interface to create two jdbc resources: jdbc/test-datasource and jdbc/live-datasource which connect to different copies of the same schema, on different servers, different credentials etc. Say I want to deploy this to glassfish with and point it at the test datasource, I might have this in my sun-web.xml: ... <resource-ref> <res-ref-name>jdbc/datasource</res-ref-name> <jndi-name>jdbc/test-datasource</jndi-name> </resource-ref> ... but sun-web.xml goes inside my war, right? surely there must be a way to do this through the management interface Am I even trying to do the right thing? Do other containers make this any easier? I'd be particularly interested in how jetty 7 handles this since I use it for development. EDIT Tomcat has a reasonable way to do this: Create $TOMCAT_HOME/conf/Catalina/localhost/webapp.xml with: <?xml version="1.0" encoding="UTF-8"?> <Context antiResourceLocking="false" privileged="true"> <!-- String resource --> <Environment name="token" value="value of token" type="java.lang.String" override="false" /> <!-- Linking to a global resource --> <ResourceLink name="jdbc/datasource1" global="jdbc/test" type="javax.sql.DataSource" /> <!-- Derby --> <Resource name="jdbc/datasource2" type="javax.sql.DataSource" auth="Container" driverClassName="org.apache.derby.jdbc.EmbeddedDataSource" url="jdbc:derby:test;create=true" /> <!-- H2 --> <Resource name="jdbc/datasource3" type="javax.sql.DataSource" auth="Container" driverClassName="org.h2.jdbcx.JdbcDataSource" url="jdbc:h2:~/test" username="sa" password="" /> </Context> Note that override="false" means the opposite. It means that this setting can't be overriden by web.xml. I like this approach because the file is part of the container configuration not the war, but it's not part of the global configuration; it's webapp specific. I guess I expect a bit more from glassfish since it is supposed to have a full web admin interface, but I would be happy enough with something equivalent to the above.

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• Repeating fields in similar database tables

  - by user1738833

  I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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• Recommended textbook for machine-level programming?

  - by Norman Ramsey

  I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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• Creating a music catalog and extracting first 30 seconds as soon as the first words are sung

  - by Rad

  I already read a question: Separation of singing voice from music. I don’t need this complex audio processing. I only need some detection mechanism that would detect that there is some voice/vocal playing while the music is playing (or not playing) I need to extract first 30 seconds when a vocalist starts singing along with full band music. See question 2 below. I want to create a music catalog using ASP.NET MVC 2 and Silverlight clients and C#.NET 4.0 programming language that would be front store. On the backend I would also like to create a desktop WPF/Windows application to create the music catalog from already existing music files, most of which have metadata in them ID3v1, ID3v2.3, ID3v2.4, iTunes MP4, WMA, Vorbis Comments and APE Tags etc. I would possibly like to create a web service that would allow catalog contributors to upload a zipped album and trigger metadata extraction of music data and extraction of music segments as described below. I would be happy if I achieve no. 1 below. Let's say I have 1000ths of songs in mp3 (or other formats) grouped in subfolders using some classification (Genre, Artists, Albums, Composers or other groupings). I want to create tables in DB that would organize songs so they can be searched based on different criteria (year, length, above classification or by song title, description etc) like what iTune store allows to their customers. I want to extract metadata from various formats (I will try to get songs in mp3 format, but there may be other popular formats) and allow music Catalog manager person to add missing data from either desktop or web applications. He or other contributors can upload zipped music via an HTML or Silverlight upload or WPF. Can anybody suggest open source libraries, articles, code snippets that can do that in an automatic way using .NET and possibly SQL Server DB? My main questions are these. This is an audio processing challenge. I want to extract 2 segments of music (questions 1 and 2): 1. How to extract a music segment: 1-2 seconds before a vocal starts singing and up to 30 seconds from that point in time and 2. Much more challenging is to find repeating segments (One would usually find or recognize the names of the songs and songs are usually known by these refrains. How would I go about creating a list of songs that go great together like what Genius from iTune does? Is there any characteristics of music that can be used to match songs? The goal is for people quickly scan and recognize songs i.e. associate melody, words with a title/album so they can make intelligent decisions like buying a song, create similar mood songs.

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• problem with select boxes - second options based on first selection

  - by Charles Marsh

  Hello All, I just posted a question about opening in a new window but if I use window.location it doesn't work?? is there a problem with my javascript? <script type="text/javascript"> function setOptions(chosen){ var selbox = document.formName.table; selbox.options.length = 0; if (chosen == " ") { selbox.options[selbox.options.length] = new Option('No diploma selected',' '); } if (chosen == "1") { selbox.options[selbox.options.length] = new Option('first choice - option one','http://www.pitman-training.com'); selbox.options[selbox.options.length] = new Option('first choice - option two','onetwo'); } if (chosen == "2") { selbox.options[selbox.options.length] = new Option('second choice - option one','twoone'); selbox.options[selbox.options.length] = new Option('second choice - option two','twotwo'); selbox.options[selbox.options.length] = new Option('second choice - option three','twothree'); selbox.options[selbox.options.length] = new Option('second choice - option four','twofour'); } if (chosen == "3") { selbox.options[selbox.options.length] = new Option('third choice - option one','threeone'); selbox.options[selbox.options.length] = new Option('third choice - option two','threetwo'); } } </script> Its a little messy I know... <form name="formName" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>"> <select name="optone" size="1" onchange="setOptions(document.formName.optone.options[document.formName.optone.selectedIndex].value);"> <option value=" " selected="selected">Please select a diploma</option> <option value="1">First Choice</option> <option value="2">Second Choice</option> <option value="3">Third Choice</option> </select> <select name="table" size="1" > <option value=" " selected="selected">No diploma selected</option> </select> <input type="submit" onclick="ob=this.form.table;window.location(ob.options[ob.selectedIndex].value)"/> </form> to be honest I'm not happy with this anyway I want a way to hide the Submit button until the second selected box has been selected...but I'm no java expert! Can anyone point me in the right direction?

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• Editing/Updating one of the results in a search query.

  - by eggman20

  Hi guys. I'm creating a page that searches for an item and then be able to edit/update it. I was able to do it when it returns just one result but when it gives me multiple results I could only edit the very last item. Below is my code: ....... $dj =$_POST[djnum]; $sql= "SELECT * From dj WHERE datajack LIKE '$dj%'"; $result = mysql_query($sql); //more code in here// while ($info =mysql_fetch_array($result)) { // display the result echo "<form action=\"dj_update.php\" method=\"POST\"><input type=\"hidden\" name=\"djnumber\" value=\"".$info['datajack']."\">"; echo "<tr><td>DJ ".$info['datajack']."</td>"; echo "<td>".$info['building']."&nbsp;</td>"; echo "<td>Rm ".$info['room']."&nbsp;</td>"; echo "<td>".$info['switch']."&nbsp;</td>"; echo "<td>".$info['port']."&nbsp;</td>"; echo "<td>".$info['notes']."&nbsp;</td>"; echo "<td style=\"text-align:center;\"><input type=\"Submit\" value=\"Edit\" ></td></tr>"; } // more code here // Then this is the screen shot of the result: The idea is the user should be able to click on "Edit" and be able to edit/update that particular item. But when I click any of the Edit button I could only edit the last item. What am I missing here? Is there an easier way to do this? Thanks guys and Happy new year!

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• Why does C# exit when calling the Ada elaboration routine using debug?

  - by erict

  I have a DLL created in Ada using GPS. I am dynamically loading it and calling it successfully both from Ada and from C++. But when I try to call it from C#, the program exits on the call to Elaboration init. What am I missing? The exact same DLL is perfectly happy getting called from C++ and Ada. Edit: If I start the program without Debugging, it also works with C#. But if I run it with the Debugger, then it exits on the call to ElaborationInit. There are no indications in any of the Windows event logs. If the Ada DLL is Pure, and I skip the elaboration init call, the actual function DLL is called correctly, so it has something to do with the elaboration. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace CallingDLLfromCS { class Program { [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern IntPtr LoadLibrary(string dllToLoad); [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true)] public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern bool FreeLibrary(IntPtr hModule); [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate int AdaCallable2_dlgt(int val); static AdaCallable2_dlgt fnAdaCallable2 = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void ElaborationInit_dlgt(); static ElaborationInit_dlgt ElaborationInit = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void AdaFinal_dlgt(); static AdaFinal_dlgt AdaFinal = null; static void Main(string[] args) { int result; bool fail = false; // assume the best IntPtr pDll2 = LoadLibrary("libDllBuiltFromAda.dll"); if (pDll2 != IntPtr.Zero) { // Note the @4 is because 4 bytes are passed. This can be further reduced by the use of a DEF file in the DLL generation. IntPtr pAddressOfFunctionToCall = GetProcAddress(pDll2, "AdaCallable@4"); if (pAddressOfFunctionToCall != IntPtr.Zero) { fnAdaCallable2 = (AdaCallable2_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaCallable2_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdainit"); if (pAddressOfFunctionToCall != IntPtr.Zero) { ElaborationInit = (ElaborationInit_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(ElaborationInit_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdafinal"); if (pAddressOfFunctionToCall != IntPtr.Zero) AdaFinal = (AdaFinal_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaFinal_dlgt)); else fail = true; if (!fail) { ElaborationInit.Invoke(); // ^^^^^^^^^^^^^^^^^^^^^^^^^ FAILS HERE result = fnAdaCallable2(50); Console.WriteLine("Return value is " + result.ToString()); AdaFinal(); } FreeLibrary(pDll2); } } } }

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• linq to sql with nservicebus table lock issue

  - by IGoor

  I am building a system using NServiceBus and my DataLayer is using Linq 2 SQL. The system is made up of 2 services. Service1 receives messages from NSB. It will query Table1 in my database and inserts a record into Table1 If a certain condition is met a new NSB message is sent to the 2nd service Service2 will update records also in Table1 when it receives messages from Service1 and it does some other non database related work. Service2 is a long running process. The problem I am having is the moment Service2 updates a record in Table1, the table is locked. The lock seems to be in place until Service2 has completed all it is processing. i.e. The lock is not released after my datacontext is disposed. This causes the query in Service1 to timeout. Once Service2 completes processing, Service1 resumes processing again without problem. So for example Service1 code may look like: int x =0; using (DataContext db = new DataContext()) { x = (from dp in db.Table1 select dp).Count(); // this line will timeout while service2 is processing Table1 t = new Table1(); t.Data = "test"; db.Table1.InsertOnSubmit(t); db.SubmitChanges(); } if(x % 50 == 0) CallService2(); The code in service2 may look like: using (DataContext db = new DataContext()) { Table1 t = db.Table1.Where(t => t.id == myId); t.Data = "updated"; db.SubmitChanges(); } // I would have expected the lock to have been released at this point, but this is not the case. DoSomeLongRunningTasks(); // lock will be released once service2 exits I don't understand why the lock is not released when the datacontext is disposed in Service2. To get around the problem I have been calling: db.ExecuteCommand("SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED"); and this works, but I am not happy using it. I want to solve this problem properly. Has any one experienced this sort of problem before and does any one know how to solve it? Why is the lock not released after the datacontext has been disposed? Thanks in advance. p.s. sorry for the extremely long post.

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• JSON.Net: deserializing polymorphic types without specifying the assembly

  - by Frank Schwieterman

  I see that using JSON.Net, I can decode polymorphic objects if a $type attribute specifies the specific type of the JSON object. In all the examples I've seen, $type includes the namespace. Is it possible to make this work including just a simple typename without the assembly? I'd be happy to specify a default assembly to the JsonSerializer if thats possible I am able to deserialize the JSON using: public class SingleAssemblyJsonTypeBinder : SerializationBinder { private readonly Assembly _assembly; private Dictionary _typesBySimpleName = new Dictionary(StringComparer.OrdinalIgnoreCase); private Dictionary _simpleNameByType = new Dictionary(); public SingleAssemblyJsonTypeBinder(Assembly assembly) { _assembly = assembly; _typesBySimpleName = new Dictionary<string, Type>(); foreach (var type in _assembly.GetTypes().Where(t => t.IsPublic)) { if (_typesBySimpleName.ContainsKey(type.Name)) throw new InvalidOperationException("Cannot user PolymorphicBinder on a namespace where multiple public types have same name."); _typesBySimpleName[type.Name] = type; _simpleNameByType[type] = type.Name; } } public override Type BindToType(string assemblyName, string typeName) { Type result; if (_typesBySimpleName.TryGetValue(typeName.Trim(), out result)) return result; return null; } public override void BindToName(Type serializedType, out string assemblyName, out string typeName) { string name; if (_simpleNameByType.TryGetValue(serializedType, out name)) { typeName = name; assemblyName = null;// _assembly.FullName; } else { typeName = null; assemblyName = null; } } } ... public static JsonSerializerSettings GetJsonSerializationSettings() { var settings = new JsonSerializerSettings(); settings.Binder = new SingleAssemblyJsonTypeBinder(typeof(MvcApplication).Assembly); settings.TypeNameHandling = TypeNameHandling.Objects; return settings; } .... var serializer = JsonSerializer.Create(settings); I haven't been able to make this work with MVC though, I'm configuring json deserialization per the code below in Application_Start, and the object is deserialized, but using the base type one. GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.Binder = new SingleAssemblyJsonTypeBinder(this.GetType().Assembly); GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameHandling = TypeNameHandling.All; GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.TypeNameAssemblyFormat = FormatterAssemblyStyle.Simple;

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• how to handle a array of objects in a session

  - by Robert

  Hello, In the project I'm working on I have got a list List<Item> with objects that Is saved in a session. Session.Add("SessionName", List); In the Controller I build a viewModel with the data from this session var arrayList = (List<Item>)Session["SessionName"]; var arrayListItems= new List<CartItem>(); foreach (var item in arrayList) { var listItem = new Item { Amount = item.Amount, Variant= item.variant, Id = item.Id }; arrayListItems.Add(listItem); } var viewModel = new DetailViewModel { itemList = arrayListItems } and in my View I loop trough the list of Items and make a form for all of them to be able to remove the item. <table> <%foreach (var Item in Model.itemList) { %> <% using (Html.BeginForm()) { %> <tr> <td><%=Html.Hidden(Settings.Prefix + ".VariantId", Item .Variant.Id)%> <td> <%=Html.TextBox(Settings.Prefix + ".Amount", Item.Amount)%></td> <td> <%=Html.Encode(Item.Amount)%> </td> <td> <input type="submit" value="Remove" /> </td> </tr> <% } %> <% } %> </table> When the post from the submit button is handeld the item is removed from the array and post back exactly the same viewModel (with 1 item less in the itemList). return View("view.ascx", viewModel); When the post is handled and the view has reloaded the value's of the html.Hidden and Html.Textbox are the value's of the removed item. The value of the html.Encode is the correct value. When i reload the page the correct values are in the fields. Both times i build the viewModel the exact same way. I cant find the cause or solution of this error. I would be very happy with any help to solve this problem Thanx in advance for any tips or help

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• Setting up Netbeans/Eclipse for Linux Kernel Development

  - by red.october

  Hi: I'm doing some Linux kernel development, and I'm trying to use Netbeans. Despite declared support for Make-based C projects, I cannot create a fully functional Netbeans project. This is despite compiling having Netbeans analyze a kernel binary that was compiled with full debugging information. Problems include: files are wrongly excluded: Some files are incorrectly greyed out in the project, which means Netbeans does not believe they should be included in the project, when in fact they are compiled into the kernel. The main problem is that Netbeans will miss any definitions that exist in these files, such as data structures and functions, but also miss macro definitions. cannot find definitions: Pretty self-explanatory - often times, Netbeans cannot find the definition of something. This is partly a result of the above problem. can't find header files: self-explanatory I'm wondering if anyone has had success with setting up Netbeans for Linux kernel development, and if so, what settings they used. Ultimately, I'm looking for Netbeans to be able to either parse the Makefile (preferred) or extract the debug information from the binary (less desirable, since this can significantly slow down compilation), and automatically determine which files are actually compiled and which macros are actually defined. Then, based on this, I would like to be able to find the definitions of any data structure, variable, function, etc. and have complete auto-completion. Let me preface this question with some points: I'm not interested in solutions involving Vim/Emacs. I know some people like them, but I'm not one of them. As the title suggest, I would be also happy to know how to set-up Eclipse to do what I need While I would prefer perfect coverage, something that only misses one in a million definitions is obviously fine SO's useful "Related Questions" feature has informed me that the following question is related: http://stackoverflow.com/questions/149321/what-ide-would-be-good-for-linux-kernel-driver-development. Upon reading it, the question is more of a comparison between IDE's, whereas I'm looking for how to set-up a particular IDE. Even so, the user Wade Mealing seems to have some expertise in working with Eclipse on this kind of development, so I would certainly appreciate his (and of course all of your) answers. Cheers

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• Best of both worlds: browser and desktop game?

  - by Ricket

  When considering a platform for a game, I've decided on multi-platform (Win/Lin/Mac) but can't make up my mind as far as browser vs. desktop. As I'm not all too far in development, and now having second thoughts, I'd like your opinion! Browser-based games using Java applets: market penetration is reasonably high (for version 6, it's somewhere around 60% I believe?) using JOGL, 3D performance/quality is decent; certainly good enough to render the crappy 3D graphics that I make there's the (small?) possibility of porting something to Android great for an audience of gamers who switch computers often; can sit down at any computer, load a webpage and play it also great for casual gamers or less knowledgeable gamers who are quite happy with playing games in a browser but don't want to install more things to their computer written in a high-level language which I am more familiar with than C++ - but at the same time, I would like to improve my skills with C++ as it is probably where I am headed in the game industry once I get out of school... easier update process: reload the page. Desktop games using good ol' C++ and OpenGL 100% market penetration, assuming complete cross-platform; however, that number reduces when you consider how many people will go through downloading and installing an executable compared to just browsing to a webpage and hitting "yes" to a security warning. more trouble to maintain the cross-platform; but again, for learning purposes I would embrace the challenge and the knowledge I would gain better performance all around true full screen, whereas browser games often struggle with smooth full screen graphics (especially on Linux, in my experience) can take advantage of distribution platforms such as Steam more likely to be considered a "real" game, whereas browser and Java games are often dismissed as not being real games and therefore not played by "hardcore gamers" installer can be large; don't have to worry so much about download times Is there a way to have the best of both worlds? I love Java applets, but I also really like the reasons to write a desktop game. I don't want to constantly port everything between a Java applet project and a C++ project; that would be twice the work! Unity chose to write their own web player plugin. I don't like this, because I am one of the people that will not install their web player for anything, and I don't see myself being able to convince my audience to install a browser plugin. What are my options? Are there other examples out there besides Unity, of games that have browser and desktop versions? Did I leave out anything in the pro/con lists above?

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• Google Code + SVN or GitHub + Git

  - by Nazgulled

  Let me start by telling you that I never used anything besides SVN and I'm also a Windows user. I have a couple of simple projects that are open-source, others are on there way when I'm happy enough to release their source code but either way, I was thinking of using Google Code and SVN to share the source code of my projects instead of providing a link to the source on my website. This as always been a pain cause I had to update the binaries and the code every time I released a new version. This would also help me out to have a backup of my code some where instead of just my local machine (I used to have a local Subversion server running). What I want from a service like this is very simple... I just want a place to store my source code that people can download if they want, allows me to control revisions and provide a simple and easy issue system so people can submit bugs and stuff like that. I guess both of them have this. But I don't want to host any binaries in their websites, I want this to be hosted on my website so I can control download statistics with my own scripts, I also don't have the need for wiki pages as I prefer to have all the documentation in my own website. Does anyone of this services provide a way to "disable" features like wiki and downloads and don't show them at all for my project(s)? Now, I'm sure there are lots of pros and cons about using Google Code with SVN and GitHub with Git (of course) but here's what it's important for me on each one and why I like them: Google Code: As with any Google page, the complexity is almost non-existent Everyone (or almost) as a Google account and this is nice if people want to report problems using the issues system GitHub: May (or may not) be a little more complex (not a problem for me though) than Google's pages but... ...has a much prettier interface than Google's service It needs people to be registered on GitHub to post about issues I like the fact that with Git, you have your own revisions locally (can I use TortoiseGit for this or?) Basically that's it, not much I know... What other, most common, pros and cons can you tell me about each site/software? Keep in mind that my projects are simple, I'm probably the only one who will ever develop these projects on these repositories (or maybe not, for now I will)

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• Design patterns and interview question

  - by user160758

  When I was learning to code, I read up on the design patterns like a good boy. Long after this, I started to actually understand them. Design discussions such as those on this site constantly try to make the rules more and more general, which is good. But there is a line, over which it becomes over-analysis starts to feed off itself and as such I think begins to obfuscate the original point - for example the "What's Alternative to Singleton" post and the links contained therein. http://stackoverflow.com/questions/1300655/whats-alternative-to-singleton I say this having been asked in both interviews I’ve had over the last 2 weeks what a singleton is and what criticisms I have of it. I have used it a few times for items such as user data (simple key-value eg. last file opened by this user) and logging (very common i'm sure). I've never ever used it just to have what is essentially global application data, as this is clearly stupid. In the first interview, I reply that I have no criticisms of it. He seemed disappointed by this but as the job wasn’t really for me, I forgot about it. In the next one, I was asked again and, as I wanted this job, I thought about it on the spot and made some objections, similar to those contained in the post linked to above (I suggested use of a factory or dependency injection instead). He seemed happy with this. But my problem is that I have used the singleton without ever using it in this kind of stupid way, which I had to describe on the spot. Using it for global data and the like isn’t something I did then realised was stupid, or read was stupid so didn’t do, it was just something I knew was stupid from the start. Essentially I’m supposed to be able to think of ways of how to misuse a pattern in the interview? Which class of programmers can best answer this question? The best ones? The medium ones? I'm not sure.... And these were both bright guys. I read more than enough to get better at my job but had never actually bothered to seek out criticisms of the most simple of the design patterns like this one. Do people think such questions are valid and that I ought to know the objections off by heart? Or that it is reasonable to be able to work out what other people who are missing the point would do on the fly? Or do you think I’m at least partially right that the question is too unsubtle and that the questions ought to be better thought out in order to make sure only good candidates can answer. PS. Please don’t think I’m saying that I’m just so clever that I know everything automatically - I’ve learnt the hard way like everyone else. But avoiding global data is hardly revolutionary.

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• List of checkboxes

  - by Andrea Girardi

  Hi all, Happy New Year to all. I'm a newbie in VB.NET and ASP.NET. This is my problem: I retrieve a list of records from DB and, for every row, I need to show 4 checkboxes. I can use a checkboxlist for every rows, but it's not so clear how I can process the results after the submit. I've some object and some operations available for that object. From database I extract a list of object with all operations. For every operation I want to show a check box to enable or disable the operation. The result is something like that: OBJ1 - url - [] [x] [] OBJ2 - url - [] [x] [x] On url I've an href to another page created using the Id retrieved from DB. To create that I used this code: <td class="column-filename"> <strong> <asp:Label runat="server" Text='<%#DataBinder.Eval(Container.DataItem, "GroupName")%>'></asp:Label> </strong> </td> <td align="left"> <span style="vertical-align:middle"> <asp:CheckBoxList runat="server" ID="operations" RepeatDirection="Horizontal" RepeatLayout="Table"> <asp:ListItem Text="View"></asp:ListItem> <asp:ListItem Text="Upload"></asp:ListItem> <asp:ListItem Text="Move"></asp:ListItem> <asp:ListItem Text="Delete"></asp:ListItem> <asp:ListItem Text="Rename"></asp:ListItem> <asp:ListItem Text="Replace"></asp:ListItem> </asp:CheckBoxList> </span> </td> </asp> </asp> my problem is: how can I parse all checkboxes? could you help me or send me a link or any other resources to solve my issue? many thanks! Andrea

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• Good design of mapping Java Domain objects to Tables (using Hibernate)

  - by M. McKenzie

  Hey guys, I have a question that is more in the realm of design, than implementation. I'm also happy for anyone to point out resources for the answer and I'll gladly, research for myself. Highly simplified Java and SQL: Say I have a business domain POJO called 'Picture' with three attributes. class Picture int idPicture String fileName long size Say I have another business domain POJO called "Item" with 3 attributes Class Item int idItem String itemName ArrayList itemPictures These would be a normal simple relationship. You could say that 'Picture' object, will never exist outside an 'Item' object. Assume a picture belongs only to a specific item, but that an item can have multiple pictures Now - using good database design (3rd Normal Form), we know that we should put items and pictures in their own tables. Here is what I assume would be correct. table Item int idItem (primary key) String itemName table Picture int idPicture (primary key) varchar(45) fileName long size int idItem (foreign key) Here is my question: If you are making Hibernate mapping files for these objects. In the data design, your Picture table needs a column to refer to the Item, so that a foreign key relation can be maintained. However,in your business domain objects - your Picture does not hold a reference/attribute to the idItem - and does not need to know it. A java Picture instance is always instantiated inside an Item instance. If you want to know the Item that the Picture belongs to you are already in the correct scope. Call myItem.getIdItem() and myItem.getItemPictures(),and you have the two pieces of information you need. I know that Hibernate tools have a generator that can auto make your POJO's from looking at your database. My problem stems from the fact that I planned out the data design for this experiment/project first. Then when I went to make the domain java objects, I realized that good design dictated that the objects hold other objects in a nested way. This is obviously different from the way that a database schema is - where all objects(tables) are flat and hold no other complex types within them. What is a good way to reconcile this? Would you: (A) Make the hibernate mapping files so that Picture.hbm.xml has a mapping to the POJO parent's idItem Field (if it's even possible) (B) Add an int attribute in the Picture class to refer to the idItem and set it at instantiation, thus simplifying the hbm.xml mapping file by having all table fields as local attributes in the class (C) Fix the database design because it is wrong, dork. I'd truly appreciate any feedback

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• Why i get everytime the error-message that i've already sent the headers

  - by mikep

  Hey, i've another question about web-programming. I programmed a login script, but everytime when i try to login it says that i've send the header informations already. Here are the 2 files: <?php if($_GET['logout'] == 1) { setcookie('authorized', 1, time()-3600); } ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Login - photoAdminSite</title> </head> <style type="text/css"> body { text-align: center; font-family: helvetica; } #loginForm { padding: 1em; background: #e3e3e3; width: 260px; margin: 3em auto 0; text-align: left; } </style> <body> <div id="loginForm"> <form method="post" action="confirm_login_credentials.php"> <h2>LOGIN</h2> <p>Username: <input type="text" name="username" /></p> <p>Password: <input type="password" name="password" /></p> <p><input type="submit" value="Login" name="submit" /></p> </form> </div> </body> </html> <?php $username = $_POST['username']; $password = $_POST['password']; require 'database.php'; $q = "SELECT id FROM users_photoadminsite WHERE user_name = '$username' AND password = '$password'"; $result = $mysqli->query($q) or die(mysqli_error()); if (mysqli_num_rows($result) == 1) { setcookie('authorized', 1, 0); header("Location: index.php"); } else { header("Location: login.php"); } ?> i would be really happy about some helpful answers.

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• DB Design Pattern - Many to many classification / categorised tagging.

  - by Robin Day

  I have an existing database design that stores Job Vacancies. The "Vacancy" table has a number of fixed fields across all clients, such as "Title", "Description", "Salary range". There is an EAV design for "Custom" fields that the Clients can setup themselves, such as, "Manager Name", "Working Hours". The field names are stored in a "ClientText" table and the data stored in a "VacancyClientText" table with VacancyId, ClientTextId and Value. Lastly there is a many to many EAV design for custom tagging / categorising the vacancies with things such as Locations/Offices the vacancy is in, a list of skills required. This is stored as a "ClientCategory" table listing the types of tag, "Locations, Skills", a "ClientCategoryItem" table listing the valid values for each Category, e.g., "London,Paris,New York,Rome", "C#,VB,PHP,Python". Finally there is a "VacancyClientCategoryItem" table with VacancyId and ClientCategoryItemId for each of the selected items for the vacancy. There are no limits to the number of custom fields or custom categories that the client can add. I am now designing a new system that is very similar to the existing system, however, I have the ability to restrict the number of custom fields a Client can have and it's being built from scratch so I have no legacy issues to deal with. For the Custom Fields my solution is simple, I have 5 additional columns on the Vacancy Table called CustomField1-5. This removes one of the EAV designs. It is with the tagging / categorising design that I am struggling. If I limit a client to having 5 categories / types of tag. Should I create 5 tables listing the possible values "CustomCategoryItems1-5" and then an additional 5 many to many tables "VacancyCustomCategoryItem1-5" This would result in 10 tables performing the same storage as the three tables in the existing system. Also, should (heaven forbid) the requirements change in that I need 6 custom categories rather than 5 then this will result in a lot of code change. Therefore, can anyone suggest any DB Design Patterns that would be more suitable to storing such data. I'm happy to stick with the EAV approach, however, the existing system has come across all the usual performance issues and complex queries associated with such a design. Any advice / suggestions are much appreciated. The DBMS system used is SQL Server 2005, however, 2008 is an option if required for any particular pattern.

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• I'm searching for a messaging platform (like XMPP) that allows tight integration with a web applicat

  - by loxs

  Hi, At the company I work for, we are building a cluster of web applications for collaboration. Things like accounting, billing, CRM etc. We are using a RESTfull technique: For database we use CouchDB Different applications communicate with one another and with the database via http. Besides, we have a single sign on solution, so that when you login in one application, you are automatically logged to the other. For all apps we use Python (Pylons). Now we need to add instant messaging to the stack. We need to support both web and desktop clients. But just being able to chat is not enough. We need to be able to achieve all of the following (and more similar things). When somebody gets assigned to a task, they must receive a message. I guess this is possible with some system daemon. There must be an option to automatically group people in groups by lots of different properties. For example, there must be groups divided both by geographical location, by company division, by job type (all the programers from different cities and different company divisions must form a group), so that one can send mass messages to a group of choice. Rooms should be automatically created and destroyed. For example when several people visit the same invoice, a room for them must be automatically created (and they must auto-join). And when all leave the invoice, the room must be destroyed. Authentication and authorization from our applications. I can implement this using custom solutions like hookbox http://hookbox.org/docs/intro.html but then I'll have lots of problems in supporting desktop clients. I have no former experience with instant messaging. I've been reading about this lately. I've been looking mostly at things like ejabberd. But it has been a hard time and I can't find whether what I want is possible at all. So I'd be happy if people with experience in this field could help me with some advice, articles, tales of what is possible etc.

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