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  • Need a cleaner way, which avoids too many 'if statements', to write this method for inputing data in

    - by indiehacker
    What is the best way to reference datastore model attributes without using the four 'if statements' I have in the below sample code, which seem messy and inefficient. For real-world code I may have a situation of 100 attributes such as self.var1, self.var2, ... self.varN that I want to some how reference with just an integer (or strings) as an argument to some method. class PixelObject(db.Model): zoom0 = db.ListProperty(int) zoom1 = db.ListProperty(int) zoom2 = db.ListProperty(int) zoom3 = db.ListProperty(int) zoom4 = db.ListProperty(int) def inputZoomData(self, zoomInteger, input_data): """input_data goes to specified attribute based on if 0,1,2,3,or 4 is argument""" if zoomInteger == 0: self.zoom0 = input_data if zoomInteger == 1: self.zoom1 = input_data if zoomInteger == 2: self.zoom2 = input_data if zoomInteger == 3: self.zoom3 = input_data if zoomInteger == 4: self.zoom4 = input_data

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  • DB Architecture : Linking to intersection or to main tables?

    - by Jean-Nicolas
    Hi, I'm creating fantasy football system on my website but i'm very confuse about how I should link some of my table. Tables The main table is Pool which have all the info about the ruling of the fantasy draft. A standard table User, which contains the usual stuff. Intersection table called pools_users which contains id,pool_id,user_id because a user could be in more than one pool, and a pool contains more than 1 user. The problem Table Selections = that's the table that is causing problem. That's the selection that the user choose for his pool. This is related to the Player table but thats not relevant for this problem. Should I link this table to the table Pools_users or should I link it with both main table Pool and User. This table contains id,pool_id,user_id,player_id,... What is the best way link my tables? When I want to retrieve my data, I normally want the information to be divided BY users. "This user have those selections, this one those selections, etc).

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  • Can you modify SQL DB schema in a transaction to know if all changes were applied?

    - by Chris F
    As part of my (new) database version control methodology, I'm writing a "change script" and want the change script to insert a new row into the SchemaChangeLog table if the script is executed successfully, or to reverse changes if any single change in the script fails. Is it possible to do schema changes in a transaction and only if it gets committed to then do the INSERT? For example (psuedo-code, I'm not too good with SQL): SET XACT_ABORT ON BEGIN TRANSACTION PRINT 'Add Col2 to Table1' IF NOT EXIST (SELECT * FROM sys.columns WHERE NAME='Col2' AND object_id=OBJECT_ID('Table1')) BEGIN ALTER TABLE [dbo].[Table1] ADD Col2 int NULL END -- maybe COMMIT here? INSERT INTO SchemaChangeLog VALUES(...) COMMIT TRANSACTION

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  • Multi-client C# ODBC (Sybase/Oracle/MSSQL) table access question.

    - by Hamish Grubijan
    I am working on a feature that would allow clients pick a unique identifier (ci_name). The code below is a generic version that gets expanded to the right sql depending on the vendor. Hopefully it makes sense. #include "sql.h" create table client_identification ( ci_id TYPE_ID IDENTITY, ci_name varchar(64) not null, constraint ci_pk primary key (ci_name) ); go CREATE_SEQUENCE(ci_id) There will be simple stored procedures for adding, retrieving, and deleting these user records. This will be used by several admins. This will not happen very frequently, but there is still a possibility that something will be added or deleted since the list was initially retrieved. I have not yet decided if I need to detect the case of a double delete, but the user name cannot be created twice - primary key constraint will object. I want to be able to detect this particular case and display something like: "you snooze - you loose." :) I would like to leverage the pk constraint instead of doing some extra sql gymnastics. So, how can I detect this case cleanly, so that it works in MS SQL 2008, Sybase, and Oracle? I hope to do better than catch a general ODBC exception and parse out the text and look for what Sybase, Oracle, and MSSQL would give me back. Oracle is a little different. We actually prepend these variables to the Oracle version of stored procedures because they are not available otherwise: Vret_val out number, Vtran_count in out number, Vmessage_count in out number, Thanks. General helpful tips and comments are welcome, except for naming convention ones ( I do not have a choice here, plus I mangled the actual names a bit).

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  • What strategies are efficient to handle concurrent reads on heterogeneous multi-core architectures?

    - by fabrizioM
    I am tackling the challenge of using both the capabilities of a 8 core machine and a high-end GPU (Tesla 10). I have one big input file, one thread for each core, and one for the the GPU handling. The Gpu thread, to be efficient, needs a big number of lines from the input, while the Cpu thread needs only one line to proceed (storing multiple lines in a temp buffer was slower). The file doesn't need to be read sequentially. I am using boost. My strategy is to have a mutex on the input stream and each thread locks - unlocks it. This is not optimal because the gpu thread should have a higher precedence when locking the mutex, being the fastest and the most demanding one. I can come up with different solutions but before rush into implementation I would like to have some guidelines. What approach do you use / recommend ?

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  • DB Interface Design Optimization: Is it better to optimise for Fewer requests of smaller data size?

    - by Overflow
    The prevailing wisdom in webservices/web requests in general is to design your api such that you use as few requests as possible, and that each request returns therefore as much data as is needed In database design, the accepted wisdom is to design your queries to minimise size over the network, as opposed to minimizing the number of queries. They are both remote calls, so what gives?

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  • In python beyond 'exec string' is there a way to 'import' using the db as a filesystem

    - by molicule
    Although it does not seem possible, I wanted to put this out there to see if others had some innovative solutions to 'dynamically loading and executing code in python' So if one saved code in a database, one could read it and 'exec it', however if one wanted to use it in a similar fashion to the filesystem, one would need to 'save and load the compiled .pyc' create an 'import dbimp' ala 'import imp' etc. any pointers? ideas? thoughts?

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  • What hash algorithms are parallelizable? Optimizing the hashing of large files utilizing on multi-co

    - by DanO
    I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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  • SQL to return the rownum of a specific row? (using Oracle db)

    - by jedierikb
    In Oracle 10g, I have this SQL: select dog.id as dogId from CANINES dog order by dog.codename asc which returns: id -- 204 203 206 923 I want to extend this query to determine the oracle rownum of a dog.id in this resultset. I have tried select rownum from (select dog.id as dogId from CANINES dog order by dog.codename asc) where dog.id=206 But this does not work out very well (it returns 1 no matter which dog.id I match on). I was expecting to get back 3. Thanks for your help! Notes http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html I am pretty sure I do not need to use rowid

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  • What's the proper approach for writing multi-path "story" flows?

    - by Basiclife
    Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

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  • Displaying Longitude and Latitude values stored in a SQLite db as a Route on a MapView in Android (N

    - by LordSnoutimus
    I am currently in the process of creating an application that records current location of a mobile device in intervals, displaying the route as a coloured line on the device in real-time. At the same time the application is storing the longitude and latitude in a SQLite database as I want the user to be able to bring up that specific route again. The route has a primary key and each waypoint is linked to that route by a foreign key. What would be the easiest way to display the saved route on the map?.

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  • Running applictions via ruby and multi-core support? (OSX)

    - by Nick Faraday
    Hi All, I'm looking for some tutorials/resources/tips that will show me how to run applications via a ruby script. I have several small tools that we use in our day to day operations that I want to manage their tasks in one ruby script. Basically what I'm trying to do is: run app via ruby script. (wait for result) get result code (success, or error msg) if ok, start the app on its next task. Also each of the tasks are independent so I'd like to take advantage of the 8 cores on my MacPro and run 8 instances at a time. Any resources you could point me towards would be greatly appreciated!

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  • Should I Split Tables Relevant to X Module Into Different DB? Mysql

    - by Michael Robinson
    I've inherited a rather large and somewhat messy codebase, and have been tasked with making it faster, less noodly and generally better. Currently we use one big database to hold all data for all aspects of the site. As we need to plan for significant growth in the future, I'm considering splitting tables relevant to specific sections of the site into different databases, so if/when one gets too large for one server I can more easily migrate some user data to different mysql servers while retaining overall integrity. I would still need to use joins on some tables across the new databases. Is this a normal thing to do? Would I incur a performance hit because of this?

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  • Multi domain rails app. How to intelligently use MVC?

    - by denial
    Background: We have app a, b, and plan to add more apps into this same application. The apps are similar enough they could share many views, assets, and actions. Currently a,b live in a single rails app(2.3.10). c will be similar enough that it could also be in this rails app. The problem: As we continue to add more apps to this one app, there's going to be too much case logic that the app will soon become a nightmare to maintain. There will also be potential namespace issues. However, the apps are very similar in function and layout, it also makes sense to keep them in one app so that it's one app to maintain(since roughly 50% of site look/functionality will be shared). What we are trying to do is keep this as clean as possible so it's easy for multiple teams to work on and easy to maintain. Some things we've thought about/are trying: Engines. Make each app an engine. This would let us base routes on the domain. It also allows us to pull out controllers, models and views for the specific app. This solution does not seem ideal as we won't be reusing the apps any time soon. And explicitly stating the host in the routes doesn't seem right. Skinning/themes. The auth logic would be different between the apps. Each user model would be different. So it's not just a skinning problem. In app/view add folder sitea for sitea views, siteb for siteb views and so on. Do the same for controllers and models. This is still pretty messy and since it didn't follow naming conventions, it did not work with rails so nicely and made much of the code messier. Making another rails app. We just didn't want to maintain the same controller or view in 2 apps if they are identical. What we want to do is make the app intelligently use a controller based on the host. So there would be a sessions controller for each app, and perhaps some parent session controller for shared logic(not needed now). In each of these session controllers, it handles authentication for that specific app. So if the domain is a.mysite.com, it would use session controller for app a and know to use app a's views,models,controllers. And if the domain is b.mysite, it would use the session controller for b. And there would be a user model for a and user model for b, which also would be determined by the domain. Does anyone have any suggestions or experience with this situation? And ideally using rails 2.3.x as updating to rails 3 isn't an option right now.

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  • How do I mimic Windows Explorer multi-select/drag-n-drop behavior in a DataGridView?

    - by bsh152s
    I'm trying to mimic the way Windows Explorer handles multiple selection. In a default DataGridView, you can select multiple items using Ctrl-click. But if you release the Ctrl key and then try and drag/drop the selected items, it clears the selected items and only selects the "hit" row. I found the following solution somewhere online. protected override OnMouseDown(MouseEventArgs e) { int hitRowIndex = HitTest(e.X, e.Y).RowIndex; if(!SelectedRows.Contains(Rows[hitRowIndex])) { base.OnMouseDown(); } } However, this causes other side effects. With the CTRL key pressed and mousing down on a selected item, the item remains selected. This makes sense because the mousedown event is bypassed if the row clicked on is selected. From looking at the behavior of Windows Explorer, it looks like the deselection of an item with the CTRL key held is not handled until the MouseUp event. Has anyone tried to do this?

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  • the best way to make codeigniter website multi-language. calling from lang arrays depends on lang se

    - by artmania
    Hi friends, I'm researching hours and hours, but I could not find any clear, efficient way to make it :/ I have a codeigniter base website in English and I have to add a Polish language now. What is the best way to make my site in 2 language depending visitor selection? is there any way to create array files for each language and call them in view files depends on Session from lang selection? I don't wanna use database. Appreciate helps! I'm running out of deadline :/ thanks!!

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  • How do I use a concatenation of 2 columns in a SQL DB in ASP.NET properly?

    - by user293357
    I'm using LinqToSql like this with a CheckBoxList in ASP.NET: var teachers = from x in dc.teachers select x; cbl.DataSource = teachers; cbl.DataTextField = "name"; cbl.DataValueField = "teacherID"; cbl.DataBind(); I want to display both "firstname" and "name" in the DataTextField however. I found this solution but I'm using LINQ: http://stackoverflow.com/questions/839223/concatenate-two-fields-in-a-dropdown How do I do this?

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  • Where to begin with multi-threaded programming with c++?

    - by zoke
    I'm trying to implement my own IRC client as a personal proejct and I realized I needed a way to read and write from the socket at the same time. I realized I could have a reading thread which reads from the socket in the background and puts data in a queue and I could have another thread which writes data from a queue to the socket. However I have no idea on how to start with multithreaded programing or how to do it with c++. Where do I go from here?

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  • How do I efficiently locate key-value pairs in a multi-dimensional PHP array?

    - by Kyle Noland
    I have an array in PHP as a result of the following query to a Wordpress database: SELECT * FROM wp_postmeta WHERE post_id = :id I am returned a multidimensional array that looks like this: Array ( [0] => Array ( [meta_id] => 380 [post_id] => 72 [meta_key] => _edit_last [meta_value] => 1 ) ... etc. What is the best way to find a particular key-value pair in this array? For instance, how would I located the row where [meta_key] = event_name so that I can extract that same row's [meta_value] value into a PHP variable? I realize I could turn this into many individual MySQL queries. Does anyone have an opinion of the efficiency of doing 10 SQL queries in a row rather than searching the array 10 times? I would think since the array is in memory, that will be the fastest method to find the values I need. Alternatively, is there a better way to query the database from the beginning so that my result set is formatted in a way that is easier to search?

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  • CLR: Multi Param Aggregate, Argument not in Final Output?

    - by OMG Ponies
    Why is my delimiter not appearing in the final output? It's initialized to be a comma, but I only get ~5 white spaces between each attribute using: SELECT [article_id] , dbo.GROUP_CONCAT(0, t.tag_name, ',') AS col FROM [AdventureWorks].[dbo].[ARTICLE_TAG_XREF] atx JOIN [AdventureWorks].[dbo].[TAGS] t ON t.tag_id = atx.tag_id GROUP BY article_id The bit for DISTINCT works fine, but it operates within the Accumulate scope... Output: article_id | col ------------------------------------------------- 1 | a a b c I only have rudimentary C# API knowledge... C# Code: using System; using System.Data; using System.Data.SqlClient; using System.Data.SqlTypes; using Microsoft.SqlServer.Server; using System.Xml.Serialization; using System.Xml; using System.IO; using System.Collections; using System.Text; [Serializable] [SqlUserDefinedAggregate(Format.UserDefined, MaxByteSize = 8000)] public struct GROUP_CONCAT : IBinarySerialize { ArrayList list; string delimiter; public void Init() { list = new ArrayList(); delimiter = ","; } public void Accumulate(SqlBoolean isDistinct, SqlString Value, SqlString separator) { delimiter = (separator.IsNull) ? "," : separator.Value ; if (!Value.IsNull) { if (isDistinct) { if (!list.Contains(Value.Value)) { list.Add(Value.Value); } } else { list.Add(Value.Value); } } } public void Merge(GROUP_CONCAT Group) { list.AddRange(Group.list); } public SqlString Terminate() { string[] strings = new string[list.Count]; for (int i = 0; i < list.Count; i++) { strings[i] = list[i].ToString(); } return new SqlString(string.Join(delimiter, strings)); } #region IBinarySerialize Members public void Read(BinaryReader r) { int itemCount = r.ReadInt32(); list = new ArrayList(itemCount); for (int i = 0; i < itemCount; i++) { this.list.Add(r.ReadString()); } } public void Write(BinaryWriter w) { w.Write(list.Count); foreach (string s in list) { w.Write(s); } } #endregion }

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  • Adding Information in SQLite

    - by Cam
    Hi All, I am having trouble with my Android App when adding information into SQLite. I am relatively new to Java/SQLite and though I have followed a lot of tutorials on SQLite and have been able to get the example code to run I am unable to get tables to be created and data to import when running my own app. I have included my code in two Java files Questions (Main Program) and QuestionData (helper class represents the database). Questions.java: public class Questions extends Activity { private QuestionData questions; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.quiztest); questions = new QuestionData(this); try { Cursor cursor = getQuestions(); showQuestions(cursor); } finally { questions.close(); } } private Cursor getQuestions() { //Select Query String loadQuestions = "SELECT * FROM questionlist"; SQLiteDatabase db = questions.getReadableDatabase(); Cursor cursor = db.rawQuery(loadQuestions, null); startManagingCursor(cursor); return cursor; } private void showQuestions(Cursor cursor) { // Collect String Values from Query and Display them this part of the code is wokring fine when there is data present. QuestionData.java public class QuestionData extends SQLiteOpenHelper { private static final String DATABASE_NAME = "TriviaQuiz.db" ; private static final int DATABASE_VERSION = 2; public QuestionData(Context ctx) { super(ctx, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE questionlist (_id INTEGER PRIMARY KEY AUTOINCREMENT, QID TEXT, QQuestion TEXT, QAnswer TEXT, QOption1 TEXT, QOption2 TEXT, QOption3 TEXT, QCategoryTagLvl1 TEXT, QCategoryTagLvl2 TEXT, QOptionalTag1 TEXT, QOptionalTag2 TEXT, QOptionalTag3 TEXT, QOptionalTag4 TEXT, QOptionalTag5 TEXT, QTimePeriod TEXT, QDifficultyRating TEXT, QGenderBias TEXT, QAgeBias TEXT, QRegion TEXT, QWikiLink TEXT, QValidationLink1 TEXT, QValidationLink2 TEXT, QHint TEXT, QLastValidation TEXT, QNotes TEXT, QMultimediaType TEXT, QMultimediaLink TEXT, QLastAsked TEXT);"); db.execSQL("INSERT INTO questionlist (_id, QID, QQuestion, QAnswer, QOption1, QOption2, QOption3, QCategoryTagLvl1, QCategoryTagLvl2, QOptionalTag1, QOptionalTag2, QOptionalTag3, QOptionalTag4, QOptionalTag5, QTimePeriod, QDifficultyRating, QGenderBias, QAgeBias, QRegion, QWikiLink, QValidationLink1, QValidationLink2, QHint, QLastValidation, QNotes, QMultimediaType, QMultimediaLink, QLastAsked)"+ "VALUES (null,'Q00001','Example','Ans1','Q1','Q2','Q3','Q4','','','','','','','','','','','','','','','','','','','','')"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); onCreate(db); } } Any suggestions at all would be great. I have tried debugging which suggests that the database does not exist. Thanks in advance for your assistance.

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