key combination - Page 602

What are appropriate ways to represent relationships between people in a database table?

- by Emilio

I've got a table of people - an ID primary key and a name. In my application, people can have 0 or more real-world relationships with other people, so Jack might "work for" Jane and Tom might "replace" Tony and Bob might "be an employee of" Rob and Bob might also "be married to" Mary. What's the best way to represent this in the database? A many to many intersect table? A series of self joins? A relationship table with one row per relationship pair and type, where I insert records for the relationship in both directions?

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Base-camp Style Subdomains and IDs of Models

- by Newy

I have an app that has Basecamp-style subdomains, that is, I have Projects, Users, Apples and Oranges. The Users, Apples and Oranges are all keyed to a Project and only exist in the http://project.myapp.com. I added a project_id to Users, Apples and Oranges and everything works, except of course that the ids of those three objects increment globally, and throughout my app I lookup objects by that id. This doesn't seem like best practice. Should I instead do lookups by a secondary key? How does that affect efficiency? If there's a good blog post that covers this, would be wesome.

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Confused by Perl grep function

- by titaniumdecoy

I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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NHibernate Unique Constraint on Name and Parent Object fails because NH inserts Null

- by James

Hi, I have an object as follows Public Class Bin Public Property Id As Integer Public Property Name As String Public Property Store As Store End Class Public Class Store Public Property Id As Integer Public Property Bins As IEnumerable(Of Bin) End Class I have a unique constraint in the database on Bin.Name and BinStoreID to ensure unique names within stores. However, when NHibernate persists the store, it first inserts the Bin records with a null StoreID before performing an update later to set the correct StoreID. This violates the Unique Key If I persist two stores with a Bin of the same name because The Name columns are the same and the StoreID is null for both. Is there something I can add to the mapping to ensure that the correct StoreID is included in the INSERT rather than performing an update later? We are using HiLo identity generation so we are not relying on DB generated identity columns Thanks James

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sql server : get default value of a column

- by luke

Hello, I execute a select to get the structure of a table. I want to get info about the columns like its name or if it's null or if it's primary key.. I do something like this ....sys.columns c... c.precision, c.scale, c.is_nullable as isnullable, c.default_object_id as columndefault, c.is_computed as iscomputed, but for default value i get the id..something like 454545454 but i want to get the value "xxxx". What is the table to search or what is the function to convert that id to the value. Thanks

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Sorting nested hash in ruby

- by Rabbott

Provided the following ruby hash: { cat: { 1: 2, 2: 10, 3: 11, 4: 1 }, wings: { 1: 3, 2: 5, 3: 7, 4: 7 }, grimace: { 1: 4, 2: 5, 3: 5, 4: 1 }, stubborn: { 1: 5, 2: 3, 3: 7, 4: 5 } } How can I sort the hash by the sum of 'leaf' excluding "4", for instance the value to compare for "cat" would be (2 + 10 + 11) = 23, the value for "wings" would be (3 + 5 + 7) = 15 so if I was comparing just those two they would be in the correct order, highest sum on top. It is safe to assume that it will ALWAYS be {1: value, 2: value, 3: value, 4: value} as those are keys for constants I have defined. It is also safe to assume that I will only ever want to exclude the key "4", and always use the keys "1", "2", and "3"

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After extending the User model in django, how do you create a ModelForm?

- by mlissner

I extended the User model in django to include several other variables, such as location, and employer. Now I'm trying to create a form that has the following fields: First name (from User) Last name (from User) Location (from UserProfile, which extends User via a foreign key) Employer (also from UserProfile) I have created a modelform: from django.forms import ModelForm from django.contrib import auth from alert.userHandling.models import UserProfile class ProfileForm(ModelForm): class Meta: # model = auth.models.User # this gives me the User fields model = UserProfile # this gives me the UserProfile fields So, my question is, how can I create a ModelForm that has access to all of the fields, whether they are from the User model or the UserProfile model? Hope this makes sense. I'll be happy to clarify if there are any questions.

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How can I redirect the output of Perl's system() to a filehandle?

- by syker

With the open command in Perl, you can use a filehandle. However I have trouble getting back the exit code with the open command in Perl. With the system command in Perl, I can get back the exit code of the program I'm running. However I want to just redirect the STDOUT to some filehandle (no stderr). My stdout is going to be a line-by-line output of key-value pairs that I want to insert into a mao in perl. That is why I want to redirect only my stdout from my Java program in perl. Is that possible? Note: If I get errors, the errors get printed to stderr. One possibility is to check if anything gets printed to stderr so that I can quite the Perl script.

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System.WIndows.Application static members are thread safe?

- by Lirik

The Application static members are supposed to be thread safe: The public static (Shared in Visual Basic) members of this type are thread safe. In addition, the FindResource and TryFindResource methods and the Properties and Resources properties are thread safe.1 How much can we trust that statement in a multithreaded environment when calling static member methods of System.Windows.Application? Update: It's all in reference to this question: http://stackoverflow.com/questions/2463822/threading-errors-with-application-loadcomponent-key-already-exists/2463866#2463866 I never thought I'd see a real bug in the library, but this must be the day for me... that question seems to show a genuine bug. Usually it's "user error," but this doesn't seem to be the case.

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Facebook status.get API throws 500 HTTP status code

- by Charles Prakash Dasari

I have an APP that calls Facebook status.get method via the REST server - restserver.php using session key method. This app works fine for most of the users, but for one user I consistently receive HTTP 500 status code. Since this doesn't have any specific Facebook error message, it is almost impossible for me to debug this. Anyone faced a similar problem? What could be wrong with this user account? I checked the privacy options that I could think of and they look fine. Also, for the same user, I can use friends.get method without any problem. EDIT: I tried in Facebook forums as well, but it was of no use. Any pointers in the direction towards debugging/troubleshooting this problem are also appreciated.

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Linq to sql Error "Data at the root level is invalid " for nullable xml column

- by Mukesh

I have Created a table like CREATE TABLE [dbo].[tab1]( [Id] [int] NOT NULL, [Name] [varchar](100) NOT NULL, [Meta] [xml] NULL, CONSTRAINT [PK_tab1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY] When I am doing linq to sql query to fetch a data it throw an error "data at the root level is invalid linq". In further investigation I come to know that the meta column is null in that case. In real it is nullable Do I have to remove the nullable and set some blank root node as default or there is some another way to get rid of the error. My linq Query which throws error var obj1= (from obj in dbContext.tab1s where obj.id== 123 select obj).FirstOrDefault<Tab1>();

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MySQL Volleyball Standings

- by Torez

I have a database table full of game by game results and want to know if I can calculate the following: GP (games played) Wins Loses Points (2 points for each win, 1 point for each lose) Here is my table structure: CREATE TABLE `results` ( `id` int(10) unsigned NOT NULL auto_increment, `home_team_id` int(10) unsigned NOT NULL, `home_score` int(3) unsigned NOT NULL, `visit_team_id` int(10) unsigned NOT NULL, `visit_score` int(3) unsigned NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ; And a few testing results: INSERT INTO `results` VALUES(1, 1, 21, 2, 25); INSERT INTO `results` VALUES(2, 3, 21, 4, 17); INSERT INTO `results` VALUES(3, 1, 25, 3, 9); INSERT INTO `results` VALUES(4, 2, 7, 4, 22); INSERT INTO `results` VALUES(5, 1, 19, 4, 20); INSERT INTO `results` VALUES(6, 2, 24, 3, 26); Here is what a final table would look like: +-------------------+----+------+-------+--------+ | Team Name | GP | Wins | Loses | Points | +-------------------+----+------+-------+--------+ | Spikers | 4 | 4 | 0 | 8 | | Leapers | 4 | 2 | 2 | 6 | | Ground Control | 4 | 1 | 3 | 5 | | Touch Guys | 4 | 0 | 4 | 4 | +-------------------+----+------+-------+--------+

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Many-to-Many Relationships in MySQL

- by Kaji

I've been reading up on foreign keys and joins recently, and have been pleasantly surprised that many of the basic concepts are things I'm already putting into practice. For example, with one project I'm currently working on, I'm organizing word lists, and have a table for the sets, like so: `words` Table `word_id` `headword` `category_id` `categories` Table `category_id` `category_name` Now, generally speaking this would be a one-to-many relationship, with several words being placed under a single category with the foreign key category_id. Let's assume for a moment, however, that a user chooses to add another category to a word, making it many-to-many—Is there a way to set up my words table to handle additional categories for words without creating extra columns like category_2, category_3, etc.?

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Hiding a value in an Android application

- by Ewan

Hi, I need to hide a value in a mobile (Android OS) application. As far as I can see, encrypting the value is of no use as the key to the encryption mechanism must be available to the program and is thus available to an attacker reverse-engineering the code. So, it seems that the only "solution" is to hide the secret value in the application as well as possible, obviously not ideal. Any comments? Am I missing something? If not, what's the best way to hide the value? Thanks for your ideas! Ewan

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Are there commercially deployed and used .NET CAS (Code Access Security) based applications?

- by Dinis Cruz

I've seen a couple threads here on SO that ask about what CAS is and how to use it.My specific is specifically focused on real-world usages of CAS. For example: DotNetNuke did some efforts in the past to be able to run under Medium Trust: is that still true? what is the % of DNN that run in partial trust (i.e. not full trust)? what & of DNN modules run in partial trust?) Sharepoint defaults to a Partially-Trusted environment on dlls executed from the bin folder: How many 'commercially' available WebParts can run in this bin folder (without changing the policy)? The key here is to be able to point to CAS success stories, so that other companies feel that they should also invest in writing CAS-enabled apps

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C++ porting templates to Red hat enterprise linux version 5

- by mkal

#include <sys/stat.h> #include <sys/types.h> #include <unistd.h> template <class OutType> bool getVAL(OutType &value_out, const std::string &key) { return false; } int main (int argc, char*argv[]) { mode_t a; getVAL(a, "abc"); } test.cpp:6: error: ISO C++ forbids declaration of ‘parameter’ with no type test.cpp: In function ‘int main(int, char**)’: test.cpp:13: error: no matching function for call to ‘getVAL(mode_t&, const char [4])’

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SQL Sentry First Impressions

- by AjarnMark

After struggling to defend my SQL Servers from a political attack recently, I realized that I needed better tools to back me up, and SQL Sentry is the leading candidate. A couple of weeks ago, seemingly from out of nowhere, complaints from the business users started coming in that one of the core internal applications was running dramatically slower than normal, and fingers were being pointed at the SQL Server. Unfortunately, we don’t have a production DBA whose entire job is to monitor and maintain our SQL Servers. The responsibility falls to me to do the best I can, investing only a small portion of my time, because there are so many other responsibilities to take care of, and our industry is still deep in recession. I inherited these SQL Servers and have made significant improvements in process and procedure, but I had not yet made the time to take real baseline measurements or keep a really close eye on the performance. Like many DBAs, I wrote several of my own tools and used the “built-in tools” like Profiler, PerfMon, and sp_who2 (did I mention most of our instances are SQL Server 2000?). These have all served me well for in-the-moment troubleshooting and maintenance, but they really fell down on the job when I was called upon to “prove” that SQL Server performance was acceptable and more importantly had not degraded recently (i.e. historical comparisons). I really didn’t have anything from a historical comparison perspective, but I was able to show that current performance was acceptable, and deflect attention back onto other components (which in fact turned out to be the real culprit). That experience dramatically illustrated the need for better monitoring tools. Coincidentally, I had been talking recently to my boss about the mini nightmare of monitoring several critical and interdependent overnight jobs that operate on separate instances of SQL Server. Among other tools, I had been using Idera’s SQL Job Manager which is a free tool and did a nice job of showing me job schedules and histories in a nice calendar view. This worked fairly well, and for the money (did I mention it was free?) it couldn’t be beat. But it is based on the stored job history in MSDB, and there were other performance problems that we ran into when we started changing the settings for how much job history to retain, in order to be able to look back a month or more in the calendar view. Another coincidence (if you believe in such things) was that when we had some of those performance challenges, I posted a couple of questions to the #sqlhelp hashtag on Twitter and Greg Gonzalez (@SQLSensei) suggested I check out SQL Sentry’s Event Manager. At the time, I just thought he worked there, but later found out that he founded the company. When I took a quick look at the features & benefits, the one that really jumped out at me is Chaining and Queueing which sounded like it would really help with our “interdependent jobs on different servers” issue. I know that is a lot of background story and coincidences, but hopefully you have stuck with me so far, and now we have arrived at the point where last week I downloaded and installed the 30-day trial of the SQL Sentry Power Suite, which is Event Manager plus Performance Advisor. And I must say that I really like what I see so far. Here are a few highlights: Great Support. I had two issues getting the trial setup and monitoring a handful of our servers. One of which was entirely my fault (missed a security setting in SQL 2008) and the other was mostly my fault (late change to some config settings that were apparently cached and did not get refreshed properly). In both cases, the support staff at SQL Sentry were very responsive and rather quickly figured out what the cause and fix was for each of them. This left me with a great impression of the company. Kudos to them! Chaining and Queueing. While I have not yet activated this feature, I am very excited about the possibilities. We have jobs on three different instances of SQL Server that have to be run in a certain order, and each has to finish before the next can successfully begin, and I believe this feature will ensure just that. It has been a real pain in the backside when one of those jobs runs just a little too long and does not finish before the job on another instance starts, thus triggering a chain reaction of either outright job failures, or worse, successful completion of completely invalid processing. Calendar View. I really, really like the Event Manager calendar view where I can see all jobs and events across all instances and identify potential resource contention as well as windows of opportunity for maintenance activity. Very well done, and based on Event Manager’s own database of accumulated historical information rather than querying the source instances every time. Performance Advisor Dashboard History View. This view let’s me quickly select a date and time range and it displays graphs of key SQL Server and Windows metrics. This is exactly the thing I needed to answer the “has performance changed recently” question at the beginning of this post. Reporting Services Subscription Jobs with Report Name. This was a big and VERY pleasant surprise. If you have ever looked at the list of SQL Server jobs that SQL Server Reporting Services creates when you make a Subscription, you will notice that they all have some sort of GUID as the name of the job. This is really ugly, and really annoying because when you are just looking at the SQL Agent and Job Activity Monitor, if you see that Job X failed, you really do not have any indication in the name or the properties of the Job itself, as to what Report that was for. But with SQL Sentry Event Manager you do. The Jobs list in the Navigator pane in SQL Sentry, amazingly, displays the name of the Report that the Subscription Job is for. And when you open it to see more details, it shows you the full Reporting Services path to that Report, so you can immediately track it down in the Report Manager in case you want to identify/notify the owner or edit the Subscription information. I did not expect this at all, but I sure do like it. HOORAY! That is just my first impressions from using the tools for a few days. And I haven’t even gotten into how it showed me where I was completely mistaken about one aspect of my SQL Server disk configurations. I’ll share that lesson in another blog entry. But I have to say it again, the combination of Event Manager and Performance Advisor working together have really made me a fan.

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On Windows XP, programmatically set Pagefile to "No Paging File" on single c: drive

- by NBPC77

I'm trying to write a C#/.NET application that optimizes the hard drives for our XP workstations Set pagefile to "No paging file" Reboot Run a defrag utility to optimize the data and apps Create a contiguous page file Reboot, run pagedefrag from Sysinternals I'm really struggling with #1. I delete the following key: SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PagingFiles Upon reboot, the System Control Panel shows "No page file", but c:\pagefile.sys still exists and its in use by the SYSTEM process so I can't delete it and I can't optimize HD. I tried using PendingFileRenamingOperations and that bombs out too. I tried using WMI: Win32_PageFileSetting, but that only lets you set sizes (not zero--defaults to 2MB). Of course, if I do the manual steps outlined above, it works. I think I need an API call to make this happen.

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sqlite ERROR no such column

- by Richard

Hi, Does anyone here have some experience with this error? Only If I use the WHERE clause, I get this error. I use php PDO to get the results. And this is my simple table $sql = "CREATE TABLE samenvatting ( stem_id INTEGER PRIMARY KEY AUTOINCREMENT, poll_id TEXT, stem_waarde_id TEXT, totaal INTEGER )"; $crud->rawQuery($sql); $poll_id = "somepoll"; $records = $crud->rawSelect('SELECT * FROM samenvatting WHERE poll_id=´.$poll_id); pdo abstract class public function conn() { isset($this->username); isset($this->password); if (!$this->db instanceof PDO) { $this->db = new PDO($this->dsn, $this->username, $this->password); $this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } } public function rawSelect($sql) { $this->conn(); return $this->db->query($sql); } Thanks, Richard

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Is OO design's strength in semantics or encapsulation?

- by Phil H

Object-oriented design (OOD) combines data and its methods. This, as far as I can see, achieves two great things: it provides encapsulation (so I don't care what data there is, only how I get values I want) and semantics (it relates the data together with names, and its methods consistently use the data as originally intended). So where does OOD's strength lie? In constrast, functional programming attributes the richness to the verbs rather than the nouns, and so both encapsulation and semantics are provided by the methods rather than the data structures. I work with a system that is on the functional end of the spectrum, and continually long for the semantics and encapsulation of OO. But I can see that OO's encapsulation can be a barrier to flexible extension of an object. So at the moment, I can see the semantics as a greater strength. Or is encapsulation the key to all worthwhile code?

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Flex datagrid multiple rows single file

- by Vish

Hi, I have a flex datagrid with 3 columns. The first column contains the image name(unique key). The other two columns have username and size details. I want to split the username into lastname, firstname, address and some other stuff. Can we have multiple rows in the grid for one image? Tried multi-line, it works but we need to keep adding spaces and its cumbersome. Since each row in the flex datagrid is represented by one index in the XMLList which is enumerated, is there a way to have more than one row assigned to one image and shown in the grid? something like this.. Thanks, Vish.

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How to fix rotations in a Rubik's Cube?

- by Eindbaas

I'm trying to create a Rubik's Cube in Flash & Papervision and i'm really stuck here. I'm up to the point where i can rotate any plane of cubes once, but after that...it's messed up because all local coordinate systems are messy. I dont really know where to go from here, can anybody give any advice on what do do? I'm not looking for 'read about transformation matrices', i know i should (and i am doing that), but i'm not really sure what to look for. My idea is that, after each rotation, i should fix each coordinate system of each cube again, but i have no idea how. Any hints on what i want to achieve (in words), and why, are much appreciated. http://dl.dropbox.com/u/250155/rubik/main.html (you can press the K key once ;) )

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mysql error in query for timestamp interval

- by nik parsa

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Google Maps - user to pinpoint a location

- by JohnB

Hi, Is it possible to allow users of my website to mark places on a map I display using Google Maps API? I need to then save that location coordinates to a db. I've been looking through the google maps API, I found that I can use the web service to do searches like this: http://maps.google.com/maps/geo?q=Maine,+United+States&output=json&oe=utf8\&sensor=false&key=my_key But I am not sure it's working on a house number level (which I need it to) and I'm not sure how to display a 'did you mean?' to the user when he misspells the address.. Anyone have an idea? Thanks,

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Global find object references in NHibernate

- by Miral

Is it possible to perform a global reversed-find on NHibernate-managed objects? Specifically, I have a persistent class called "Io". There are a huge number of fields across multiple tables which can potentially contain an object of that type. Is there a way (given a specific instance of an Io object), to retrieve a list of objects (of any type) that actually do reference that specific object? (Bonus points if it can identify which specific fields actually contain the reference, but that's not critical.) Since the NHibernate mappings define all the links (and the underlying database has corresponding foreign key links), there ought to be some way to do it.

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