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  • Django DecimalField returns "None" instead of empty value

    - by Ed
    Is there a way to force django to display nothing instead of "None" for a Decimal Field that's been left blank? In my template, I show a list of all the values for a particular field. Each value is hyperlinked to a page that displays the results of a query filtered on that value. But because there are some entries with null value, my list includes actual DecimalField entries and "None" for all those that are empty. When a user clicks on None, django throws a validation error because you cannot query a DecimalField using a string. I could write if statements checking all instances of decimal fields for Nones and skipping them, but that is far from an elegant solution. Any advice? This is one part of the code, though there are other templates that derive the None value in slightly different manners: {% for item in choices %} <a href={% url app_views.field_choice item %}>{{ item }}</a><br> {% endfor %}

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  • Parallel Computing in .Net 4.0

    - by kaleidoscope
    Technorati Tags: Ram,Parallel Computing in .Net 4.0 Parallel computing is the simultaneous use of multiple compute resources to solve a computational problem: To be run using multiple CPUs A problem is broken into discrete parts that can be solved concurrently Each part is further broken down to a series of instructions Instructions from each part execute simultaneously on different CPUs Parallel Extensions in .NET 4.0 provides a set of libraries and tools to achieve the above mentioned objectives. This supports two paradigms of parallel computing Data Parallelism – This refers to dividing the data across multiple processors for parallel execution.e.g we are processing an array of 1000 elements we can distribute the data between two processors say 500 each. This is supported by the Parallel LINQ (PLINQ) in .NET 4.0 Task Parallelism – This breaks down the program into multiple tasks which can be parallelized and are executed on different processors. This is supported by Task Parallel Library (TPL) in .NET 4.0 A high level view is shown below:

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  • Installing 64bit Java 7 - Cannot Execute Binary File

    - by warpstack
    So I downloaded the latest version of Java from Oracle so I could get a 64bit JVM on Ubuntu Server 10.10. After extracting the file and updating the alternatives I went to check my installation by running java -version and I get this error: -bash: /usr/bin/java: cannot execute binary file I'm at a loss for what to do here. My alternatives menu looks like this: Selection Path Priority Status ------------------------------------------------------------ 0 /usr/lib/jvm/java-6-openjdk/jre/bin/java 1061 auto mode 1 /usr/lib/jvm/java-6-openjdk/jre/bin/java 1061 manual mode 2 /usr/lib/jvm/java-7-openjdk-i386/jre/bin/java 1051 manual mode * 3 /usr/lib/jvm/jdk1.7.0/bin/java 3 manual mode After restarting the system I seem to be getting a totally new error when checking the java version. usr/bin/java: 1: Syntax error: end of file unexpected (expecting ")")

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  • Visual Studio error on valid SQL

    - by Sam
    I'm getting an annoying error in visual studio for SQL that executes fine. SELECT InvoiceLines.LineID, InvoiceLines.InvoiceID, InvoiceLines.Text, InvoiceLines.Rate, InvoiceLines.Count, InvoiceLines.Rate * InvoiceLines.Count AS LineTotal, ((InvoiceLines.Rate * InvoiceLines.Count) * (1 + Invoices.VatRate / 100)) * (1 - CAST(Invoices.Discount AS money) * InvoiceLines.ApplyDiscount / 100) AS LineTotalIncVat, InvoiceLines.ApplyDiscount FROM InvoiceLines LEFT JOIN Invoices ON Invoices.InvoiceID = InvoiceLines.InvoiceID What LineTotalIncVat is trying to do is compute the total for the invoice item while adding the vat and subtracting the discount, and yes, probably better to do this in code (would if I could) The error visual studio gives is: There was an error parsing the query [token line number =1, token line offset =14, token in error = InvoiceLines] Even though it will validate and execute without a problem in the query builder...

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  • An INSERT conditioned on COUNT

    - by Anders Feder
    How can I construct a MySQL INSERT query that only executes if the number of rows satisfying some condition already in the table is less than 20, and fails otherwise? That is, if the table has 18 rows satisfying the condition, then the INSERT should proceed. If the table has 23 rows satisfying the condition, then the INSERT should fail. For atomicity, I need to express this in a single query, so two requests can not INSERT at the same time, each in the 'belief' that only 19 rows satisfy the condition. Thank you.

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  • Alternatives to NSMutableArray for storing 2D grid - iOS Cocos2d

    - by SundayMonday
    I'm creating a grid-based iOS game using Cocos2d. Currently the grid is stored in an NSMutableArray that contains other NSMutableArrays (the latter are rows in the grid). This works ok and performance so far is pretty good. However the syntax feels bulky and the indexing isn't very elegant (using CGPoints, would prefer integer indices). I'm looking for an alternative. What are some alternatives data structures for 2D arrays in this situation? In my game it's very common to add and remove rows from the bottom of the grid. So the grid might start off 10x10, grow to 17x10, shrink to 8x10 and then finally end with 2x10. Note the column count is constant. I've consider using a vector<vector<Object*>>. Also I'm vaguely aware of some type of "fast array" or similar offered by Cocos2d. I'd just like to learn about best practices from other developers!

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  • How to combine two sql queries?

    - by plasmuska
    Hi Guys, I have a stock table and I would like to create a report that will show how often were items ordered. "stock" table: item_id | pcs | operation apples | 100 | order oranges | 50 | order apples | -100 | delivery pears | 100 | order oranges | -40 | delivery apples | 50 | order apples | 50 | delivery Basically I need to join these two queries together. A query which prints stock balances: SELECT stock.item_id, Sum(stock.pcs) AS stock_balance FROM stock GROUP BY stock.item_id; A query which prints sales statistics SELECT stock.item_id, Sum(stock.pcs) AS pcs_ordered, Count(stock.item_id) AS number_of_orders FROM stock GROUP BY stock.item_id, stock.operation HAVING stock.operation="order"; I think that some sort of JOIN would do the job but I have no idea how to glue queries together. Desired output: item_id | stock_balance | pcs_ordered | number_of_orders apples | 0 | 150 | 2 oranges | 10 | 50 | 1 pears | 100 | 100 | 1 This is just example. Maybe, I will need to add more conditions because there is more columns. Is there a universal technique of combining multiple queries together?

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  • How do you choose to use a specific programming language?

    - by Jesús Bracamonte
    I was having a small talk between teammates about how you choose a programming language for use in a project which lead me to think that there are many criteria to choose one in the beginning of a project but no real standard. Do you chose a programming language for the syntax and semantics? Or do you choose one because it has the best support to do certain things? Or because you have better libraries? Or do you choose it for the paradigm? What criteria do you use to choose one language when you are going to do a project?

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  • Development on Terminal or IDE [on hold]

    - by Taylor Flores
    I've been using nano, make, gcc, and gdb for 6 months now and I've found it much easier than using VS or Codeblocks. But I'm wondering now: Is development on a terminal more/less efficient that using an IDE? In what situations is one preferred more sensible than the other? I'm not asking about opinions, I want to know if there's specific reasons to use one over the other. From what I can gather: terminals can be used on environments where a GUI is not available terminal projects can be created and configured more quickly IDEs contain better syntax highlighters (ie identity highlighters) This question is C biased, but I think it's relevant to other languages as well.

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  • hibernate order by association

    - by Gary Kephart
    I'm using Hibernate 3.2, and using criteria to build a query. I'd like to add and "order by" for a many-to-one association, but I don't see how that can be done. The Hibernate query would end up looking like this, I guess: select t1.a, t1.b, t1.c, t2.dd, t2.ee from t1 inner join t2 on t1.a = t2.aa order by t2.dd <-- need to add this I've tried criteria.addOrder("assnName.propertyName") but it doesn't work. I know it can be done for normal properties. Am I missing something?

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  • What's the best platform for blogging about coding ?

    - by timday
    I'm toying with starting an occasional blog for posting odd bits of coding related stuff (mainly C++, probably). Are there any platforms which can be recommended as providing exceptionally good support (e.g syntax highlighting) for posting snippets of code ? (Or any to avoid because posting mono-spaced font blocks of text is a pain). Outcome: I accepted Josh K's answer because what I actually ended up doing was realizing I was more interested in articles than a blog style, getting back into LaTeX (after almost 20 years away from it), using the "listings" package for code, and pushing the HTML/PDF results to my ISP's static-hosting pages. (HTML generated using tex4ht). Kudos to the answers mentioning Wordpress, Tumblr and Jekyll; I spent some time looking into all of them.

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  • What are good reasons to use explicit interface implementation for the sole purpose of hiding members?

    - by Nathanus
    During one of my studies into the intricacies of C#, I came across an interesting passage concerning explicit interface implementation. While this syntax is quite helpful when you need to resolve name clashes, you can use explicit interface implementation simply to hide more "advanced" members from the object level. The difference between allowing the use of object.method() or requiring the casting of ((Interface)object).method() seems like mean-spirited obfuscation to my inexperienced eyes. The text noted that this will hide the method from Intellisense at the object level, but why would you want to do that if it was not necessary to avoid name conflicts?

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  • Rendering a variable with erb.

    - by TZer0
    I've got the following problem: I have rhtml (html minced together with ruby inside <% % and <%= % tags) stored in a database which I want to render. The information is acquired through a query. I need to be able to evaluate the information I get from the database as though as it was normal content inside the .erb-file. What I currently have: <% @mymods.each do |mod| %> <%= render_text(mod["html"])%> <% end %> Where mod["html"] is the variable containing the rhtml-code and @mymods an array of objects from the query. I have currently no idea what function I should use (render_text does, of course, not work). Help is greatly appreciated. /TZer0

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  • Using multiple aggregate functions in an algebraic expression in (ANSI) SQL statement

    - by morpheous
    I have the following aggregate functions (AGG FUNCs): foo(), foobar(), fredstats(), barneystats(). I want to know if I can use multiple AGG FUNCs in an algebraic expression. This may seem a strange/simplistic question for seasoned SQL developers - however, the but the reason I ask is that so far, all AGG FUNCs examples I have seen are of the simplistic variety e.g. max(salary) < 100, rather than using the AGG FUNCs in an expression which involves using multiple AGG FUNCs in an expression (like agg_func1() agg_func2()). The information below should help clarify further. Given tables with the following schemas: CREATE TABLE item (id int, length float, weight float); CREATE TABLE item_info (item_id, name varchar(32)); # Is it legal (ANSI) SQL to write queries of this format ? SELECT id, name, foo, foobar, fredstats FROM A, B (SELECT id, foo(123) as foo, foobar('red') as foobar, fredstats('weight') as fredstats FROM item GROUP BY id HAVING [ALGEBRAIC EXPRESSION] ORDER BY id AS A), item_info AS B WHERE item.id = B.id Where: ALGEBRAIC EXPRESSION is the type of expression that can be used in a WHERE clause - for example: ((foo(x) < foobar(y)) AND foobar(y) IN (1,2,3)) OR (fredstats(x) <> 0)) I am using PostgreSQL as the db, but I would prefer to use ANSI SQL wherever possible. Assuming it is legal to include AGG FUNCS in the way I have done above, I'd like to know: Is there a more efficient way to write the above query ? Is there any way I can speed up the query in terms of a judicious choice of indexes on the tables item and item_info ? Is there a performance hit of using AGG FUNCs in an algebraic expression like I am (i.e. an expression involving the output of aggregate functions rather than constants? Can the expression also include 'scaled' AGG FUNC? (for example: 2*foo(123) < -3*foobar(456) ) - will scaling (i.e. multiplying an AGG FUNC by a number have an effect on performance?) How can I write the query above using INNER JOINS instead?

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  • How to get all paths in drupal install

    - by Aaron
    Hi, I need to write a module that gives me a page will all possible paths in a drupal install, including orphaned pages. (site map won't work for that). I can query the url_alias table for aliases, and I can query the menu_router table for all paths, even ones set in page/feed displays in views. But, variable paths (those with arguments) get interpreted at run-time. So, is there a way to get all possible paths in a drupal install, including dynamic paths and orphans? It's catch22. I have to know all the urls ahead of time to get them.

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  • TableAdapter to return ONLY selected columns? (VS2008)

    - by MattSlay
    (VS2008) I'm trying to configure a TableAdapter in a Typed DataSet to return only a certain subset of columns from the main schema of the table on which it is based, but it always returns the entire schema (all columns) with blank values in the columns I have omitted. The TableAdpater has the default Fill and GetData() methods that come from the wizard, which contain every column in the table, which is fine. I then added a new parameterized query method called GetActiveJobsByCustNo(CustNo), and I only included a few columns in the SQL query that I actually want to be in this table view. But, again, it returns all the columns in the master table schema, with empty values for the columns I omitted. The reason I am wanting this, is so I can just get a few columns back to use that table view with AutoGenerateColumns in an ASP.NET GridView. With it giving me back EVERY column i nthe schema, my presentation GridView contains way more columns that I want to show th user. And, I want to avoid have to declare the columns in the GridView.

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  • mysql result set joining existing table

    - by Yang
    is there any way to avoid using tmp table? I am using a query with aggregate function (sum) to generate the sum of each product: the result looks like this: product_name | sum(qty) product_1 | 100 product_2 | 200 product_5 | 300 now i want to join the above result to another table called products. so that i will have a summary like this: product_name | sum(qty) product_1 | 100 product_2 | 200 product_3 | 0 product_4 | 0 product_5 | 300 i know 1 way of doing this is the dump the 1st query result to a temp table then join it with products table. is there a better way?

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  • RESTful Design: Paging Collections

    - by Koen Bok
    I am designing a REST api that needs paging (per x) enforces from the server side. What would be the right way to page through any collection of resources: Option 1: GET /resource/page/<pagenr> GET /resource/tags/<tag1>,<tag2>/page/<pagenr> GET /resource/search/<query>/page/<pagenr> Option 2: GET /resource/?page=<pagenr> GET /resource/tags/<tag1>,<tag2>?page=<pagenr> GET /resource/search/<query>?page=<pagenr> If 1, what should I do with GET /resource? Redirect to /resource/page/0, reply with some error or reply with the exact same as /resource/page/0 without redirecting?

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  • How do I select the number of distinct days in a date range?

    - by isme
    I'm trying to use the T-SQL function DATEDIFF to select the number of distinct dates in a time period. The following query: SELECT DATEDIFF(DAY, '2012-01-01 01:23:45', '2012-01-02 01:23:45') selects 1, which is one less than I want. There are two distinct dates in the range: 2012-01-01 and 2012-01-02. It is not correct to add one to the result in the general case. The following query: SELECT DATEDIFF(DAY, '2012-01-01 00:00:00', '2012-01-02 00:00:00') selects 1, which is correct, because there is only one distinct date in the range. I'm sure there is a simple bit of arithmetic that I'm missing to calculate this. Can someone help me?

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  • What are QUICK interview questions for the Microsoft stack development jobs?

    - by Dubmun
    I'm looking for your best "quick answer" technical interview questions. We are a 100% Microsoft shop and do the majority of our development on the ASP.NET web stack in C# and have a custom SOA framework also written in C#. We use a combination of Web Forms, MVC, Web Services, WCF, Entity Framework, SQL Server, TSQL, jQuery, LINQ, and TFS in a SCRUM environment. We are currently on .NET 3.5 with a very near transition to .NET 4.0. Our interviewing process includes a 55 minute interview with two technical people (usually an architect and a senior developer). The two interviewers have to share the time for questions. That isn't enough time for very many true programming problems so I'm looking for more good questions that have quick, yet meaningful, answers. We are mainly interviewing for Senior Dev positions right now but may interview for some Juniors in the future. Please help?

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  • codeigniter: how to redirect after login to current controller (php_self in regular php)

    - by krike
    Well it's not really a problem but I check if the user exist and log them in and redirect to site/members_area, but I don't want to send the user to a specific page but i want to reload the current controller. So if I login in index/home I would like to be redirected at index/home, how should I proceed? in regular php I would put in the action to redirect to current page <?php echo $_SERVER['PHP_SELF']; ?> This is the code in the framework function validate_credentials() { $this->load->model('membership_model'); $query = $this->membership_model->validate(); if($query) // if the user's credentials validated... { $data = array( 'username' => $this->input->post('username'), 'is_logged_in' => true ); $this->session->set_userdata($data); redirect('site/members_area'); //<-- this line here should be dynamic } else // incorrect username or password { $this->index(); } }

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  • Write a sql for searching with multiple conditions

    - by Lu Lu
    Hello everyone, I have a table Student with 2 fields: Name: nvarchar(256) Age: int User will use a WinForm application to input a Name and a Age for searching. If inputted Name is empty, sql will not query Name field. If inputted Age is 0, sql will not query Age field. If Name is Null and inputted Name is empty - record is matched. If Name is Null and inputted Name is not empty - record is not matched. And also similar for Age field. My problem is that how to write a sql like this. P/S: I use SQL Server 2005. Please help me. Thanks.

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  • If I were to claim I knew C++, what libraries would you expect me to know?

    - by Peter Smith
    I'm unsure as to the definition of knowing a programming language, so I'm picking C++ as an example. How much does it take to someone to be qualified as knowing C++? Should they just know the basic syntax? Template and generic-programming? Compiler flags and their purposes (Wall, the difference between O1, O2 and O3)? STL? Garbage collection strategies? Boost? Common libraries like zlib, curl, and libxml2?

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  • When to use identity comparison instead of equals?

    - by maaartinus
    I wonder why would anybody want to use identity comparison for fields in equals, like here (Java syntax): class C { private A a; public boolean equals(Object other) { // standard boring prelude if (other==this) return true; if (other==null) return false; if (other.getClass() != this.getClass()) return false; C c = (C) other; // the relevant part if (c.a != this.a) return false; // more tests... and then return true; } // getter, setters, hashCode, ... } Using == is a bit faster than equals and a bit shorter (due to no need for null tests), too, but in what cases (if any) you'd say it's really better to use == for fields inside equals?

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