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• how does Cocoa compare to Microsoft, Qt?

  - by Paperflyer

  I have done a few months of development with Qt (built GUI programatically only) and am now starting to work with Cocoa. I have to say, I love Cocoa. A lot of the things that seemed hard in Qt are easy with Cocoa. Obj-C seems to be far less complex than C++. This is probably just me, so: Ho do you feel about this? How does Cocoa compare to WPF (is that the right framework?) to Qt? How does Obj-C compare to C# to C++? How does XCode/Interface Builder compare to Visual Studio to Qt Creator? How do the Documentations compare? For example, I find Cocoa's Outlets/Actions far more useful than Qt's Signals and Slots because they actually seem to cover most GUI interactions while I had to work around Signals/Slots half the time. (Did I just use them wrong?) Also, the standard templates of XCode give me copy/paste, undo/redo, save/open and a lot of other stuff practically for free while these were rather complex tasks in Qt. Please only answer if you have actual knowledge of at least two of these development environments/frameworks/languages.

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• C# Dynamic Query Without A Database Model

  - by hitopp

  I have been searching the web for a solution to dynamic queries. I have found many different solutions (e.g. Linq to Sql, Dynamic Linq Expressions, Dynamic Query), but all of these solutions involve some sort of previous knowledge of the database (like a model in code). Maybe what I am asking is way off the deep end, but is there any possible way to dynamically query a database without a model? For example, a database has a Customers table with the following columns: CustomerID Name FavoriteColor I want to create a query as SELECT Name FROM Customers WHERE @0 = @1, where the two placeholders are populated dynamically. The resulting data does not tie to a model class and I would prefer to use some sort of framework to build the queries, not simple string concatenation. The System.Linq.Dynamic namespace came really close to fulfilling this request, but it uses a database model. I realize this is crazy, but I was just curious.

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• How to improve Visual C++ compilation times?

  - by dtrosset

  I am compiling 2 C++ projects in a buildbot, on each commit. Both are around 1000 files, one is 100 kloc, the other 170 kloc. Compilation times are very different from gcc (4.4) to Visual C++ (2008). Visual C++ compilations for one project take in the 20 minutes. They cannot take advantage of the multiple cores because a project depend on the other. In the end, a full compilation of both projects in Debug and Release, in 32 and 64 bits takes more than 2 1/2 hours. gcc compilations for one project take in the 4 minutes. It can be parallelized on the 4 cores and takes around 1 min 10 secs. All 8 builds for 4 versions (Debug/Release, 32/64 bits) of the 2 projects are compiled in less than 10 minutes. What is happening with Visual C++ compilation times? They are basically 5 times slower. What is the average time that can be expected to compile a C++ kloc? Mine are 7 s/kloc with vc++ and 1.4 s/kloc with gcc. Can anything be done to speed-up compilation times on Visual C++?

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• SQL Server architecture guidance

  - by Liam

  Hi, We are designing a new version of our existing product on a new schema. Its an internal web application with possibly 100 concurrent users (max)This will run on a SQL Server 2008 database. On of the discussion items recently is whether we should have a single database of split the database for performance reasons across 2 separate databases. The database could grow anywhere from 50-100GB over 5 years. We are Developers and not DBAs so it would be nice to get some general guidance. [I know the answer is not simple as it depends on the schema, archiving policy, amount of data etc. ] Option 1 Single Main Database [This is my preferred option]. The plan would be to have all the tables in a single database and possibly to use file groups and partitioning to separate the data if required across multiple disks. [Use schema if appropriate]. This should deal with the performance concerns One of the comments wrt this was that the a single server instance would still be processing this data so there would still be a processing bottle neck. For reporting we could have a separate reporting DB but this is still being discussed. Option 2 Split the database into 2 separate databases DB1 - Customers, Accounts, Customer resources etc DB2 - This would contain the bulk of the data [i.e. Vehicle tracking data, financial transaction tables etc]. These tables would typically contain a lot of data. [It could reside on a separate server if required] This plan would involve keeping the main data in a smaller database [DB1] and retaining the [mainly] read only transaction type data in a separate DB [DB2]. The UI would mainly read from DB1 and thus be more responsive. [I'm aware that this option makes it harder for Referential Integrity to be enforced.] Points for consideration As we are at the design stage we can at least make proper use of indexes to deal performance issues so thats why option 1 to me is attractive and its more of a standard approach. For both options we are considering implementing an archiving database. Apologies for the long Question. In summary the question is 1 DB or 2? Thanks in advance, Liam

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• Flex vs GWT again

  - by CK Lee

  Hi all, I am working on a customized web ontology editor (something like http://webprotege.stanford.edu/ which is built by GWT). My backend will be Java+Spring+Hibernate and domain models are in Java. My frontend will be something like WebProtege which requires extensive RPC call. It is quite clear that I should use GWT as I can refer to the open source code. However, due to company policy, I shall consider Flex as well. I understand Flex can remotely invoke Java backend methods via BlazeDS using AMF (Is there a Flex equivalent of GWT-RPC?). I have read discussion on GWT vs Flex vs ?. If I can make full decision sure I will go with GWT. GWT strengths like support right to left characters, support iPhone/iPad, smaller size, support JSON out of the box, support printing are not important considerations for my project. Besides GWT supports Java generic, enum; domain objects can be shared with both GWT client and server; coding are more seamlessly... anyone can suggest other strong reasons that I should only go with GWT? FYI, I have plenty of Java experience but both GWT and Flex are new to me. Thanks.

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• Pattern for creating a database schema using JDBC

  - by Space_C0wb0y

  I have a Java-application that loads data from a legacy file format into an SQLite-Database using JDBC. If the database file specified does not exist, it is supposed to create a new one. Currently the schema for the database is hardcoded in the application. I would much rather have it in a separate file as an SQL-Script, but apparently there is now easy way to execute an SQL-Script though JDBC. Is there any other way or a pattern to achieve something like this?

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• Determining whether a file is a duplicate

  - by Todd R

  Is there a reliable way to determine whether or not two files are the same? For example, two files with the same size and type may or may not be the same binarilly (yeah, I know it's not really a word). I assume that comparing one or two checksums of the files will help, but I wonder: How reliable are checksums at determining whether two files are different; what are the chances of two different files having the same checksum? Would reliability increase by applying additional checksum comparisons? Which checksum algorithm(s) would be the most efficient and/or reliable? Any ideas, suggestions or thoughts are appreciated! P.S. The code for this is being written in Java running on a nix system, but generic or platform agnostic input is most helpful.

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• Oracle database link

  - by Sunit

  I'm currently using Windows Authentication with 2 Oracle servers - SP3DSMP1 & SP3DSMP4. I created a database link on SMP1 to connect to SMP4 as: SQL create public database link LINK_SMP4 2 connect to CURRENT_USER 3 using 'SP3DSMP4'; Database link created. However when I try to do a query, I get the error: ERROR at line 1: ORA-01017: invalid username/password; logon denied Any ideas what might be wrong here? thanks Sunit

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• Connecting form to database errors

  - by Russell Ehrnsberger

  Hello I am trying to connect a page to a MySQL database for newsletter signup. I have the database with 3 fields, id, name, email. The database is named newsletter and the table is named newsletter. Everything seems to be fine but I am getting this error Notice: Undefined index: Name in C:\wamp\www\insert.php on line 12 Notice: Undefined index: Name in C:\wamp\www\insert.php on line 13 Here is my form code. <form action="insert.php" method="post"> <input type="text" value="Name" name="Name" id="Name" class="txtfield" onblur="javascript:if(this.value==''){this.value=this.defaultValue;}" onfocus="javascript:if(this.value==this.defaultValue){this.value='';}" /> <input type="text" value="Enter Email Address" name="Email" id="Email" class="txtfield" onblur="javascript:if(this.value==''){this.value=this.defaultValue;}" onfocus="javascript:if(this.value==this.defaultValue){this.value='';}" /> <input type="submit" value="" class="button" /> </form> Here is my insert.php file. <?php $host="localhost"; // Host name $username="root"; // Mysql username $password=""; // Mysql password $db_name="newsletter"; // Database name $tbl_name="newsletter"; // Table name // Connect to server and select database. mysql_connect("$host", "$username", "$password")or die("cannot connect"); mysql_select_db("$db_name")or die("cannot select DB"); // Get values from form $name=$_POST['Name']; $email=$_POST['Email']; // Insert data into mysql $sql="INSERT INTO $tbl_name(name, email)VALUES('$name', '$email')"; $result=mysql_query($sql); // if successfully insert data into database, displays message "Successful". if($result){ echo "Successful"; echo "<BR>"; echo "<a href='index.html'>Back to main page</a>"; } else { echo "ERROR"; } ?> <?php // close connection mysql_close(); ?>

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• data structure for counting frequencies in a database table-like format

  - by user373312

  i was wondering if there is a data structure optimized to count frequencies against data that is stored in a database table-like format. for example, the data comes in a (comma) delimited format below. col1, col2, col3 x, a, green x, b, blue ... y, c, green now i simply want to count the frequency of col1=x or col1=x and col2=green. i have been storing the data in a database table, but in my profiling and from empirical observation, database connection is the bottle-neck. i have tried using in-memory database solutions too, and that works quite well; the only problem is memory requirements and quirky init/destroy calls. also, i work mainly with java, but have experience with .net, and was wondering if there was any api to work with "tabular" data in a linq way using java. any help is appreciated.

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• PHP Frameworks: Do any of them compare to Visual Studio?

  - by RedEye

  Are there any coders out there that have real experience/exposure to both PHP and ASP.net? I'm a C# developer, wondering if any PHP frameworks compare to the robustness of the Visual Studio Development environment.

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• Sort months ( with strings ) algorithm

  - by Oscar Reyes

  I have this months array: ["January", "March", "December" , "October" ] And I want to have it sorted like this: ["January", "March", "October", "December" ] I'm currently thinking in a "if/else" horrible cascade but I wonder if there is some other way to do this. The bad part is that I need to do this only with "string" ( that is, without using Date object or anything like that ) What would be a good approach?

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• Avoid slowdowns while using off-site database

  - by Anders Holmström

  The basic layout of my problem is this: Website (ASP.NET/C#) hosted at a dedicated hosting company (location 1) Company database (SQL Server) with records of relevant data (location 2). Location 1 & 2 connected through VPN. Customer visiting the website and wanting to pull data from the company database. No possibility of changing the server locations or layout (i.e. moving the website to an in-office server isn't possible). What I want to do is figure out the best way to handle the data acces in this case, minimizing the need for time-expensive database calls over the VPN. The first idea I'm getting is this: When a user enters the section of the website needing the DB data, you pull all the needed tables from the database into a in-memory dataset. All subsequent views/updates to the data is done on this dataset. When the user leaves (logout, session timeout, browser closed etc) the dataset gets sent to the SQL server. I'm not sure if this is a realistic solution, and it obviously has some problems. If two web visitors are performing updates on the same data, the one finishing up last will have their changes overwriting the first ones. There's also no way of knowing you have the latest data (i.e. if a customer pulls som info on their projects and we update this info while they are viewing them, they won't see these changes PLUS the above overwriting issue will arise). The other solution would be to somehow aggregate database calls and make sure they only happen when you need them, e.g. during data updates but not during data views. But then again the longer a pause between these refreshing DB calls, the bigger a chance that the data view is out of date as per the problem described above. Any input on the above or some fresh ideas would be most welcome.

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• SQL Compact Edition database corruption

  - by jdv

  Hi, Our product is using MS SQL Compact Edition on a Windows machine (laptop). It's basically a metadata index for files we have on the filesystem. Recently we have seen databases getting corrupted. This happens when the machine is very busy moving files around and has to do a tiny bit of database changes at the same time. I was somewhat shocked that was at all possible. It was my expectation that the database would stay coherent whatever the circumstances. Of course we are doing something wrong. Things we have checked so far are: Use of only one db connection per thread specify the maximum size when opening the database The database is accessed only by one application, a .net based windows service. Are there other gotcha's?

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• How to get most recent date from an array of dates?

  - by sugarFornaciari

  Hy guys I have an array of dates such as array(5) { [0]=> string(19) "2012-06-11 08:30:49" [1]=> string(19) "2012-06-07 08:03:54" [2]=> string(19) "2012-05-26 23:04:04" [3]=> string(19) "2012-05-27 08:30:00" [4]=> string(19) "2012-06-08 08:30:55" } I would like to know which is the most recent date, comparing to the today date. Do you have any idea to do that?

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• c# finding matching words in table column using Linq2Sql

  - by David Liddle

  I am trying to use Linq2Sql to return all rows that contain values from a list of strings. The linq2sql class object has a string property that contains words separated by spaces. public class MyObject { public string MyProperty { get; set; } } Example MyProperty values are: MyObject1.MyProperty = "text1 text2 text3 text4" MyObject2.MyProperty = "text2" For example, using a string collection, I pass the below list var list = new List<>() { "text2", "text4" } This would return both items in my example above as they both contain "text2" value. I attempted the following using the below code however, because of my extension method the Linq2Sql cannot be evaluated. public static IQueryable<MyObject> WithProperty(this IQueryable<MyProperty> qry, IList<string> p) { return from t in qry where t.MyProperty.Contains(p, ' ') select t; } I also wrote an extension method public static bool Contains(this string str, IList<string> list, char seperator) { if (String.IsNullOrEmpty(str) || list == null) return false; var splitStr = str.Split(new char[] { seperator }, StringSplitOptions.RemoveEmptyEntries); foreach (string s in splitStr) foreach (string l in list) if (String.Compare(s, l, true) == 0) return true; return false; } Any help or ideas on how I could achieve this?

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• Compare Properties automatically

  - by juergen d

  I want to get the names of all properties that changed for matching objects. I have these (simplified) classes: public enum PersonType { Student, Professor, Employee } class Person { public string Name { get; set; } public PersonType Type { get; set; } } class Student : Person { public string MatriculationNumber { get; set; } } class Subject { public string Name { get; set; } public int WeeklyHours { get; set; } } class Professor : Person { public List<Subject> Subjects { get; set; } } Now I want to get the objects where the Property values differ: List<Person> oldPersonList = ... List<Person> newPersonList = ... List<Difference> = GetDifferences(oldPersonList, newPersonList); public List<Difference> GetDifferences(List<Person> oldP, List<Person> newP) { //how to check the properties without casting and checking //for each type and individual property?? //can this be done with Reflection even in Lists?? } In the end I would like to have a list of Differences like this: class Difference { public List<string> ChangedProperties { get; set; } public Person NewPerson { get; set; } public Person OldPerson { get; set; } } The ChangedProperties should contain the name of the changed properties.

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• Quickest way to compare a bunch of array or list of values.

  - by zapping

  Can you please let me know on the quickest and efficient way to compare a large set of values. Its like there are a list of parent codes(string) and each code has a series of child values(string). The child lists have to be compared with each other and find out duplicates and count how many times they repeat. code1(code1_value1, code1_value2, code3_value3, ..., code1_valueN); code2(code2_value1, code1_value2, code2_value3, ..., code2_valueN); code3(code2_value1, code3_value2, code3_value3, ..., code3_valueN); . . . codeN(codeN_value1, codeN_value2, codeN_value3, ..., codeN_valueN); The lists are huge say like there are 100 parent codes and each has about 250 values in them. There will not be duplicates within a code list. Doing it in java and the solution i could figure out is. Store the values of first set of code in as codeMap.put(codeValue, duplicateCount). The count initialized to 0. Then compare the rest of the values with this. If its in the map then increment the count otherwise append it to the map. The downfall of this is to get the duplicates. Another iteration needs to be performed on a very large list. An alternative is to maintain another hashmap for duplicates like duplicateCodeMap.put(codeValue, duplicateCount) and change the initial hashmap to codeMap.put(codeValue, codeValue). Speed is what is requirement. Hope one of you can help me with it.

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• Generate a collection of changed lines between two revisions of a file using Java

  - by mchr

  I am writing an eclipse plugin which needs to be able to determine which lines of a file have changed compared to a different version of the same file. Is there an existing class or library which I can use for this task? The closest I have found is org.eclipse.compare.internal.merge.DocumentMerger. This can be used to find the information I need but is in an internal package so is not suitable for me to use. I could copy/paste the source of this class and adapt it to my requirements. However, I am hoping there is an existing library to handle textual comparisons.

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• Database Design Question: GUID + Natural Numbers

  - by Alan

  For a database I'm building, I've decided to use natural numbers as the primary key. I'm aware of the advantages that GUID's allow, but looking at the data, the bulk of row's data were GUID keys. I want to generate XML records from the database data, and one problem with natural numbers is that I don't want to expose my database key's to the outside world, and allow users to guess "keys." I believe GUID's solve this problem. So, I think the solution is to generate a sparse, unique iD derived from the natural ID (hopefully it would be 2-way), or just add an extra column in the database and store a guid (or some other multibyte id) The derived value is nicer because there is no storage penalty, but it would be easier to reverse and guess compared to a GUID. I'm (buy) curious as to what others on SO have done, and what insights they have.

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• (SQL) Selecting from a database based on multiple pairs of pairs

  - by Owen Allen

  The problem i've encountered is attempting to select rows from a database where 2 columns in that row align to specific pairs of data. IE selecting rows from data where id = 1 AND type = 'news'. Obviously, if it was 1 simple pair it would be easy, but the issue is we are selecting rows based on 100s of pair of data. I feel as if there must be some way to do this query without looping through the pairs and querying each individually. I'm hoping some SQL stackers can provide guidance. Here's a full code break down: Lets imagine that I have the following dataset where history_id is the primary key. I simplified the structure a bit regarding the dates for ease of reading. table: history history_id id type user_id date 1 1 news 1 5/1 2 1 news 1 5/1 3 1 photo 1 5/2 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 If the user wants to select rows from the database based on a date range we would take a subset of that data. SELECT history_id, id, type, user_id, date FROM history WHERE date BETWEEN '5/3' AND '5/5' Which returns the following dataset history_id id type user_id date 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 Now, using that subset of data I need to determine how many of those entries represent the first entry in the database for each type,id pairing. IE is row 4 the first time in the database that id: 3, type: news appears. So I use a with() min() query. In real code the two lists are programmatically generated from the result sets of our previous query, here I spelled them out for ease of reading. WITH previous AS ( SELECT history_id, id, type FROM history WHERE id IN (1,2,3,4) AND type IN ('news','photo') ) SELECT min(history_id) as history_id, id, type FROM previous GROUP BY id, type Which returns the following data set. history_id id type user_id date 1 1 news 1 5/1 2 1 news 1 5/1 3 1 photo 1 5/2 4 3 news 1 5/3 5 4 news 1 5/3 6 1 news 1 5/4 7 2 photo 1 5/4 8 2 photo 1 5/5 You'll notice it's the entire original dataset, because we are matching id and type individually in lists, rather than as a collective pairs. The result I desire is, but I can't figure out the SQL to get this result. history_id id type user_id date 1 1 news 1 5/1 4 3 news 1 5/3 5 4 news 1 5/3 7 2 photo 1 5/4 Obviously, I could go the route of looping through each pair and querying the database to determine it's first result, but that seems an inefficient solution. I figured one of the SQL gurus on this site might be able to spread some wisdom. In case I'm approaching this situation incorrectly, the gist of the whole routine is that the database stores all creations and edits in the same table. I need to track each users behavior and determine how many entries in the history table are edits or creations over a specific date range. Therefore I select all type:id pairs from the date range based on a user_id, and then for each pairing I determine if the user is responsible for the first that occurs in the database. If first, then creation else edit. Any assistance would be awesome.

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• CoreData and many NSArrayController

  - by unixo

  In my CoreData Application, I've an outline view on left of main window, acting as source list (like iTunes); on the right I display a proper view, based on outline selection. Each view has its components, such as table view, connected to array controller, owned by the specific view. Very often different views display same data, for example, a table view of the same entity. From a performance point of view, is better to have a single array controller per entity and share it between all views or does CoreData cache avoid memory waste?

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• Generate XSD from 2005 SQL Server Database

  - by Robert Finlayson

  What is the easiest method to generate an XSD schema from a 2005 SQL Server Database? Would it be possible to generate one XSD schema for the entire Database (~100 tables)? I searched online and found a SQL example that generates one XSD for the one table: DECLARE @schema xml SET @schema = (SELECT * FROM MyTableName FOR XML AUTO, ELEMENTS, XMLSCHEMA('MyTableNameSchema')) SELECT @schema Outside of SQL Server, is there a third party tool that could generate the XSD file from the 2005 Database?

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• Spring Security LDAP user data caching on local database

  - by Eduardo

  After asking: http://stackoverflow.com/questions/3009740/ldap-user-data-caching-on-local-database I want to cache LDAP user data in the application local database to allow fast queries. How may I cache LDAP user data in the local database using Spring Security.

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• JavaScript: why `null == 0` is false?

  - by lemonedo

  I had to write a routine that increments the value of a variable by 1 if it is a number, or assigns 0 to the variable if it is not a number. The variable can be incremented by the expression, or be assigned null. No other write access to the variable is allowed. So, the variable can be in three states: it is 0, a positive integer, or null. My first implementation was: v >= 0 ? v += 1 : v = 0 (Yes, I admit that v === null ? v = 0 : v += 1 is the exact solution, but I wanted to be concise then.) It failed since null >= 0 is true. I was confused, since if a value is not a number, an numeric expression involving it must be false always. Then I found that null is like 0, since null + 1 == 1, 1 / null == Infinity, Math.pow(2.718281828, null) == 1, ... Strangely enough, however, null == 0 is evaluated to false. I guess null is the only value that makes the following expression false: (v == 0) === (v >= 0 && v <= 0) So why null is so special in JavaScript?

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