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• How do I create a LiveUSB that lets me install any Ubuntu version?

  - by Dariopnc

  What I'd like to do: have Ubuntu installed on a USB drive and from there install any ubuntu version on a hdd. This is kinda different from using usb-creator because I'd like to have a persistent ubuntu install on the USB drive and not upgrade it every 6 months. From there I'd like to be able to install the most recent ubuntu version. I think it's just a matter of configuring ubiquity, but don't know if this is the case and how exactly do this. EDIT: Let's clarify the persistent thing: suppose I have my USB with ubuntu precise on it suppose quantal is out in the wild suppose that I want to install quantal on the hdd of a computer suppose that I want/can use only the USB drive with precise on it I should erase/upgrade precise on the USB drive to quantal and then install it on the hard drive I don't want to touch my ubuntu install on the USB drive, I'd like to be able to install the newer ubuntu version (quantal) on a hdd from another one (precise) on a USB drive I'd better avoid upgrading the installation on the hdd Hope this helps

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• If I create a link to a folder, how can I get from that linked folder to the "real" folder from within Nautilus?

  - by snowguy

  Say I have a folder several layers down in my documents folder. And I want easy access to it from my desktop. To do that I: Go to the parent folder in Nautilus. Right click on the folder's Icon and choose Make Link Cut / Paste the new "Link to ..." folder onto my desktop. Great. And mostly this works fine for me. But suppose I want to get to that folder's parent. I can of course get there using the original path--what Nautilus calls the "link path" which I can see in the properties of the folder. But that seems harder than it ought to be. How can I click on the folder and go to the link path directly?

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• Is it possible to create a virtual drive and share via USB?

  - by Matthew

  My question is kind of hard to follow, but I'm asking if it's possible to make a virtual flash drive and sync it to another device with a USB to USB cable? To make things more clear, think of a typical flash drive. You connect it to a laptop and it shows up as a removable disk. Is it possible to make a computer a host of a "Virtual Drive" that would be connected to a USB cord on one end, and the other end connecting to another device such as a Xbox 360, or another computer.

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• Database localization

  - by Don

  Hi, I have a number of database tables that contain name and description columns which need to be localized. My initial attempt at designing a DB schema that would support this was something like: product ------- id name description local_product ------- id product_id local_name local_description locale_id locale ------ id locale However, this solution requires a new local_ table for every table that contains name and description columns that require localization. In an attempt to avoid this overhead I redesigned the schema so that only a single localization table is needed product ------- id localization_id localization ------- id local_name local_description locale_id locale ------ id locale Here's an example of the data which would be stored in this schema when there are 2 tables (product and country) requiring localization: country id, localization_id ----------------------- 1, 5 product id, localization_id ----------------------- 1, 2 localization id, local_name, local_description, locale_id ------------------------------------------------------ 2, apple, a delicious fruit, 2 2, pomme, un fruit délicieux, 3 2, apfel, ein köstliches Obst, 4 5, ireland, a small country, 2 5, irlande, un petite pay, 3 locale id, locale -------------- 2, en 3, fr 4, de Notice that the compound primary key of the localization table is (id, locale_id), but the foreign key in the product table only refers to the first element of this compound PK. This seems like 'a bad thing' from the POV of normalization. Is there any way I can fix this problem, or alternatively, is there a completely different schema that supports localization without creating a separate table for each localizable table? Update: A number of respondents have proposed a solution that requires creating a separate table for each localizable table. However, this is precisely what I'm trying to avoid. The schema I've proposed above almost solves the problem to my satisfaction, but I'm unhappy about the fact that the localization_id foreign keys only refer to part of the corresponding primary key in the localization table. Thanks, Don

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• In MVC, why can't a model create a view?

  - by MUY Belgium

  I have a web application written in Perl with a controller, some "views" and some "Models". Each "Model" is corresponding to one "View". The controller (one file) creates an Model object corresponding to each view (view is a CGI argument) then retrieve the view from the module it has just created. Indeed, this should be bad thing but can you argue a bit more about it. My first idea was that since the object "Model" depends upon the "view", then the "model" is actually a view. But also the fact that ALL the cgi parameters are passed to the Model causes the "Model" to become not truelly a view but to loose all interest, since it is only related to the current implementation of the web apps. On other words, that the "Model" keep model but loose its "comprehensiveness" ("Model" is not easily understandable). I'm am quite new in project analysis, so please do not be too harsh. Why is this bad? I have made a prototype with the main structures I have understood of this web application, made as short as possible. #Model.pm package Model; import { # this requires an attribute called "view" # and this require an argument which is the cgi params } ... #View1.pm package View1; ... #Model1.pm package ModelView1 ; base Model; use View1; sub new { my $class = shift; my $arg = shift; Model::DoSomething($arg); $self->view = new View1($arg); ... } #controller.cgi my $model = 0; ... $model = new Model1( cgi_param => params() ); #there is severall models here ... print $model->get_view()->get_html();

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• Association Mapping Details confusion?

  - by AaronLS

  I have never understood why the associations in EntityFramework look the way they do in the Mapping Details window. When I select the line between 2 tables for an association, for example FK_ApplicationSectionsNodes_FormItems, it shows this: Association Maps to ApplicationSectionNodes FormItems (key symbol) FormItemId:Int32 <--> FormItemId:int ApplicationSectionNodes (key symbol) NodeId:Int32 <--> (key symbol) NodeId : int Fortunately this one was create automatically for me based on the foreign key constraints in my database, but whenever no constraints exist, I have a hard to creating associations manually(when the database doesn't have a diagram setup) because I don't understand the mapping details for associations. FormItems table has a primary key identity column FormItemId, and ApplicationSectionNodes contains a FormItemId column that is the foreign key and has NodeId as a primary key identity column. What really makes no sense to me is why the association has anything listed about the NodeId, when NodeId doesn't have anything to do with the foreign key relationship? (It's even more confusing with self referencing relationships, but maybe if I could understand the above case I'd have a better handle). CREATE TABLE [dbo].[ApplicationSectionNodes]( [NodeID] [int] IDENTITY(1,1) NOT NULL, [OutlineText] [varchar](5000) NULL, [ParentNodeID] [int] NULL, [FormItemId] [int] NULL, CONSTRAINT [PK_ApplicationSectionNodes] PRIMARY KEY CLUSTERED ( [NodeID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY], CONSTRAINT [UQ_ApplicationSectionNodesFormItemId] UNIQUE NONCLUSTERED ( [FormItemId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[ApplicationSectionNodes] WITH NOCHECK ADD CONSTRAINT [FK_ApplicationSectionNodes_ApplicationSectionNodes] FOREIGN KEY([ParentNodeID]) REFERENCES [dbo].[ApplicationSectionNodes] ([NodeID]) GO ALTER TABLE [dbo].[ApplicationSectionNodes] NOCHECK CONSTRAINT [FK_ApplicationSectionNodes_ApplicationSectionNodes] GO ALTER TABLE [dbo].[ApplicationSectionNodes] WITH NOCHECK ADD CONSTRAINT [FK_ApplicationSectionNodes_FormItems] FOREIGN KEY([FormItemId]) REFERENCES [dbo].[FormItems] ([FormItemId]) GO ALTER TABLE [dbo].[ApplicationSectionNodes] NOCHECK CONSTRAINT [FK_ApplicationSectionNodes_FormItems] GO FormItems Table: CREATE TABLE [dbo].[FormItems]( [FormItemId] [int] IDENTITY(1,1) NOT NULL, [FormItemType] [int] NULL, CONSTRAINT [PK_FormItems] PRIMARY KEY CLUSTERED ( [FormItemId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[FormItems] WITH NOCHECK ADD CONSTRAINT [FK_FormItems_FormItemTypes] FOREIGN KEY([FormItemType]) REFERENCES [dbo].[FormItemTypes] ([FormItemTypeId]) GO ALTER TABLE [dbo].[FormItems] NOCHECK CONSTRAINT [FK_FormItems_FormItemTypes] GO

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• How should I create a mutable, varied jtree with arbitrary/generic category nodes?

  - by Pureferret

  Please note: I don't want coding help here, I'm on Programmers for a reason. I want to improve my program planning/writing skills not (just) my understanding of Java. I'm trying to figure out how to make a tree which has an arbitrary category system, based on the skills listed for this LARP game here. My previous attempt had a bool for whether a skill was also a category. Trying to code around that was messy. Drawing out my tree I noticed that only my 'leaves' were skills and I'd labeled the others as categories. Explanation of tree: The Tree is 'born' with a set of hard coded highest level categories (Weapons, Physical and Mental, Medical etc.). Fro mthis the user needs to be able to add a skill. Ultimately they want to add 'One-handed Sword Specialisation' for instance. To do so you'd ideally click 'add' with Weapons selected and then select One-handed from a combobox, then click add again and enter a name in a text field. Then click add again to add a 'level' or 'tier' first proficiency, then specialisation. Of course if you want to buy a different skill it's completely different, which is what I'm having trouble getting my head around let alone programming in. What is a good system for describing this sort of tree in code? All the other JTree examples I've seen have some predictable pattern, and I don't want to have to code this all in 'literals'. Should I be using abstract classes? Interfaces? How can I make this sort of cluster of objects extensible when I add in other skills not listed above that behave differently? If there is not a good system to use, if there a good process for working out how to do this sort of thing?

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• Best way to create an exact twitter clone? From scratch vs CMS vs any other way [closed]

  - by Akash

  I tried many already built Twitter clone scripts but none was having user-end functionality exactly as twitter. I know enough PHP to code all the twitter's features myself. But is there a faster way than coding myself? I've never used a CMS but if I do then won't I have to search a plugin for every twitter feature, like support for multiple users, options for following-unfollowing users, retweeting (reposting someone else's post), tagging? And I'm afraid that there might be some licensing issues with CMS.

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• Data Access Layer in ASP.Net: Where do I create the Connection?

  - by atticae

  If I want to create a 3-Layer ASP.Net application (Presentation Layer, Business Layer, Data Access Layer), where is the best place to create the Connection objects? So far I used a helper class in my Presentation Layer to create an IDbCommand from the ConnectionString in the web.config on each page and passed it on to the DAL classes/methods. Now I am not so sure, if this part shouldn't also be included in the DAL somehow, because it obviously is part of the Data Access. The DAL is in a separately compilated project, so I dont have access to the web.config and cannot access the connection string (right?). What is the best practice here?

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• Adding defaults and indexes to a script/generate command in a Rails Template?

  - by charliepark

  I'm trying to set up a Rails Template that would allow for comprehensive set-up of a specific Rails app. Using Pratik Naik's overview (http://m.onkey.org/2008/12/4/rails-templates), I was able to set up a couple of scaffolds and models, with a line that looks something like this ... generate("scaffold", "post", "title:string", "body:string") I'm now trying to add in Delayed Jobs, which normally has a migration file that looks like this: create_table :delayed_jobs, :force => true do |table| table.integer :priority, :default => 0 # Allows some jobs to jump to the front of the queue table.integer :attempts, :default => 0 # Provides for retries, but still fail eventually. table.text :handler # YAML-encoded string of the object that will do work table.text :last_error # reason for last failure (See Note below) table.datetime :run_at # When to run. Could be Time.now for immediately, or sometime in the future. table.datetime :locked_at # Set when a client is working on this object table.datetime :failed_at # Set when all retries have failed (actually, by default, the record is deleted instead) table.string :locked_by # Who is working on this object (if locked) table.timestamps end So, what I'm trying to do with the Rails template, is to add in that :default = 0 into the master template file. I know that the rest of the template's command should look like this: generate("migration", "createDelayedJobs", "priority:integer", "attempts:integer", "handler:text", "last_error:text", "run_at:datetime", "locked_at:datetime", "failed_at:datetime", "locked_by:string") Where would I put (or, rather, what is the syntax to add) the :default values in that? And if I wanted to add an index, what's the best way to do that?

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• Serialized values or separate table, which is more efficient?

  - by Aravind

  I have a Rails model email_condition_string with a word column in it. Now I have another model called request_creation_email_config with the following columns admin_filter_group:references vendor_service:references email_condition_string:references email_condition_string has many request_creation_email_config and request_creation_email_config belongs to email_condition_string. Instead of this model a colleague of mine is suggesting that strong the word inside the same model as comma separated values is efficient than storing as a separate model. Is that alright?

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• Create a screencast in a low end PC, but fast (maybe by sacrificing compression ?)

  - by josinalvo

  As the title suggests, I am asking a lot. We've been trying to generate some screencasts on my eeepc. recordmydesktop is doing the job decently, but only if allowed time to "compile" the video afterwards. If we ask it to do "on the fly", video and audio get out of sync. Now, we are creating many screencasts as practice (and like to watch them after, to criticize). Reducing quality is undesirable, because eventually a good practice run becomes the one we'll release. So we'd like a way to do screencasts "on the fly", with decent quality, on the low end machine. As nothing is ever free, we are willing to sacrifice: we don't care too much about compression: 20GB for a 15min video is acceptable

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• Can WebGL be used to create a tile-based multi-layer scrolling platform game?

  - by Nicholas Hill

  I've found WebGL (based on OpenGL) to be a fiendish and unforgiving framework for those learning to write HTML5-based games. Despite the presence of many examples on how to get started, I'm really struggling to understand how I could simply load a bunch of images and render them to a canvas quickly using WebGL. My specific scenario involves trying to render a map using a bespoke but simple multi-layered tile engine, where each value in a three dimensional array points to the image to use for that location in the rendered image. Think "Sonic the Hedgehog" via tilesets, tiles, maps, layers, sprites etc. Can anyone enlighten me: 1) How can I load an image that I can use as a texture in WebGL? 2) How can I dynamically select an image at run time and draw it at any co-ordinate, that I also select at run time?

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• How can I create multiple mini-sites with similar/duplicate content without hurting my search engine rank?

  - by ekpyrotic

  Essential background: I run a small company that lets members of the public post handwritten letters to their local politician (UK-based). Every week a number of early stage bills (called Early Day Motions) are submitted for debate in the House of Commons, and supporters of the motion will contact their local Members of Parliament, asking them to sign the motion. The crux: I want to target these EDMs with customised mini-sites, so when people search "EDM xxx", they find my customised mini-site, specifically targeting that EDM (i.e., "Send a handwritten letter to your MP asking them to sign EDM xxx"). At the moment, all these mini-sites (and my homepage) have duplicate content with only the relevant EDM name, number, and background image changed. (For example, http://mailmymp.com and http://mailmymp.com/edm/teaching-life-saving-skills-at-school-edm-550.php). The question: Firstly, will this hurt my potential search engine ranking? And, if so, what's the best way to target these political campaigns in an efficient manner without hurting my SEO prospects?

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• Entity Framework 5 Enum Naming

  - by Tyrel Van Niekerk

  I am using EF 5 with migrations and code first. It all works rather nicely, but there are some issues/questions I would like to resolve. Let's start with a simple example. Lets say I have a User table and a user type table. The user type table is an enum/lookup table in my app. So the user table has a UserTypeId column and a foreign key ref etc to UserType. In my poco, I have a property called UserType which has the enum type. To add the initial values to the UserType table (or add/change values later) and to create the table in the initial migrator etc. I need a UserType table poco to represent the actual table in the database and to use in the map files. I mapped the UserType property in the User poco to UserTypeId in the UserType poco. So now I have a poco for code first/migrations/context mapping etc and I have an enum. Can't have the same name for both, so do I have a poco called UserType and something else for the enum or have the poco for UserType be UserTypeTable or something? More importantly however, am I missing some key element in how code first works? I tried the example above, ran Add-Migration and it does not add the lookup table for the enum.

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• What tools and knowledge do I need to create an application which generates bespoke automated e-mails? [on hold]

  - by Seraphina

  I'd like some suggestions as to how to best go about creating an application which can generate bespoke automated e-mails- i.e. send a personalized reply to a particular individual, interpreting the context of the message as intelligently as possible... (This is perhaps too big a question to be under one title?) What would be a good starting point? What concepts do I need to know? I'd imagine that the program needs to be able trawl through e-mails as and when they come in, and search for keywords in e-mail content, in order to write an appropriate reply. So there needs to be some form of automated response embedded in the code. Machine learning and databases come to mind here, as I'm aware that google incorporates machine learning already in gmail etc. It is quite tricky to google the above topic, and find the perfect tutorial. But there are some interesting articles and papers out there: Machine Learning in Automated Text Categorization (2002) by Fabrizio Sebastiani , Consiglio Nazionale Delle Ricerche However, this is not exactly a quick start guide. I intend to add to this question, and no doubt other questions will spark off this one. I look forward to suggestions.

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• What noncluster index would be better to create on SQL Server?

  - by Junior Mayhé

  Here I am studying nonclustered indexes on SQL Server Management Studio. I've created a table with more than 1 million records. This table has a primary key. SELECT CustomerName FROM Customers Which leads the execution plan to show me: I/O cost = 3.45646 Operator cost = 4.57715 For the first attempt to improve performance, I've created a nonclustered index for this table: CREATE NONCLUSTERED INDEX [IX_CustomerID_CustomerName] ON [dbo].[Customers] ( [CustomerId] ASC, [CustomerName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this first try, I've executed the select statement and the execution plan shows me: I/O cost = 2.79942 Operator cost = 3.92001 Now the second try, I've deleted this nonclustered index in order to create a new one. CREATE NONCLUSTERED INDEX [IX_CategoryName] ON [dbo].[Categories] ( [CategoryId] ASC ) INCLUDE ( [CategoryName]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this second try, I've executed the select statement and the execution plan shows me the same result: I/O cost = 2.79942 Operator cost = 3.92001 Am I doing something wrong or this is expected? Shall I use the first nonclustered index with two fields, or the second nonclustered with one field (CategoryID) including the second field (CategoryName)?

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• SQL DB design to support user feeds (in application like facebook)

  - by Yoav

  I have a social network server with a MySql DB. I want to show the users feeds like done in Facebook. Example - UserX now Friend with userY, userX did like on postX etc. Currently I have table: C1 : UserId C2 : LogType (now friend, did like etc) C3 : ObjectId (Can be userId or postId) - set depending on the LogType. Currently to get all related logs to show to the user I do the following queries: 1. Get All user Friends userIds 2. Query all rows which C1 is in userIds (I query completed) 3. Scan the DB and see - if LogType equals DidLike, check if post's OwnerId is the userId - if yes add it to logs. And so on. Obvious this is not efficient at all. I am looking for a better way. I thought I had in mind: Create a new table (in addition to the Log table) C1 : UserId C2 : LogId (from Log table) C3 : UserID of the one who did the action When querying logs - look in the table and get related Logs (by LogId) from LogTable. Updating the table: Whenever user doing action that should be in the log: 1. Add the Log entry to LogTable. 2. Scan the DB and see which users are interested with the Log (Who my friends are, Who is the owner of the post) and add related entries to the new table. (must be done in BG). 3. If user UNFRIEND another user - then look in the logs for all rows where C3 == UNFRIENDED user id and delete them. Any opinions? Other suggestions?

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• How to create a Appointment in a Shared Calendar (Sharepoint) with VBA (Macro)?

  - by Diogo K.

  I am actually trying to make an appointment from an excel spreadsheet. I have all the information of the appointment, like subject, body, start and end dates, I actually can create an appointment but only with my personal calendar in outlook. How do I copy/move/create an appointment in a shared calendar in a sharepoint server? I've tried: Dim apOL As Object Dim objFolder As Folder Dim cro As String Set apOL = CreateObject("Outlook.Application") Set oItem = apOL.CreateItem(olApItem) Set MAPISession = apOL.Session ... cro = "stssync://sts/?ver=1.0&type=calendar&cmd=add-folder&base-url=(MY SP SERVER)&list-url=%2FLists%2FCronograma%20%20%2Fcalendar%2Easpx&guid=%7B02717CEF%2D404F%2D482F%2DA131%2D5C3C245CD268%7D&site-name=Testes&list-name=Cronograma%20-" ... Set objFolder = MAPISession.OpenSharedFolder(cro, Null,Null,Null) It gives me the error "Type Mismatch" I'd try to get the objFolder as the Sharepoint Folder then later create an local appointment and then try an Item.Move objFolder Is it the correct way?

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• Does a Postgresql dump create sequences that start with - or after - the last key?

  - by bennylope

  I recently created a SQL dump of a database behind a Django project, and after cleaning the SQL up a little bit was able to restore the DB and all of the data. The problem was the sequences were all mucked up. I tried adding a new user and generated the Python error IntegrityError: duplicate key violates unique constraint. Naturally I figured my SQL dump didn't restart the sequence. But it did: DROP SEQUENCE "auth_user_id_seq" CASCADE; CREATE SEQUENCE "auth_user_id_seq" INCREMENT 1 START 446 MAXVALUE 9223372036854775807 MINVALUE 1 CACHE 1; ALTER TABLE "auth_user_id_seq" OWNER TO "db_user"; I figured out that a repeated attempt at creating a user (or any new row in any table with existing data and such a sequence) allowed for successful object/row creation. That solved the pressing problem. But given that the last user ID in that table was 446 - the same start value in the sequence creation above - it looks like Postgresql was simply trying to start creating rows with that key. Does the SQL dump provide the wrong start key by 1? Or should I invoke some other command to start sequences after the given start ID? Keenly curious.

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• Get array's key recursively and create underscore seperated string.

  - by Nehal

  Hello Everyone, Right now i got an array which has some sort of information and i need to create a table from it. e.g. Student{ [Address]{ [StreetAddress] =>"Some Street" [StreetName] => "Some Name" } [Marks1] => 100 [Marks2] => 50 } Now I want to create database table like which contain the fields name as : Student_Address_StreetAddress Student_Address_StreetName Student_Marks1 Student_Marks2 It should be recursive so from any depth of array it can create the string in my format.

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• Can I use wikipedia/commons images to create a logo for my program?

  - by bitmask

  I'm not perfectly clear on the implications of the GFDL for reusing pictures in this manner. Would adding a reference in the git's root folder's README suffice, or would that clutter every use of the logo, as you would have to attribute all original contributors on every single usage (like, e.g. presentations, flyers, websites, ...)? The software itself qualifies as FOSS, although it doesn't have a GNU* license.

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• Is it Possible to Use Constraints on Hierarchical Data in a Self-Referential Table?

  - by pbarney

  Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to cascade on update and prevent deletion of a record if it has any "children." So I used the following: CREATE TABLE `test`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

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• [solved] Why can't I dynamically add lines to a HTML table using JavaScript in Internet Explorer?

  - by karlthorwald

  After many hours of debugging I am tired, maybe you can help me now to solve this: In a new Firefox it works, in my Internet Explorer 6 or 7 it doesn't: <html> <head> <script type="text/javascript"> function newLine() { var tdmod = document.createElement('td'); tdmod.appendChild(document.createTextNode("dynamic")); var tr = document.createElement('tr'); tr.appendChild(tdmod); var tt = document.getElementById("t1"); tt.appendChild(tr); } </script> </head> <body> <a href="#" onclick="newLine()">newLine</a> <table id="t1" border="1"> <tr> <td> static </td> </tr> </table> </body> You can klick on the link and new lines should be added to the table. Try it here: http://dl.dropbox.com/u/1508092/iejs.html#

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• Using a join with three tables when a field might be null

  - by John

  Hello, The code below works great. It combines data from two MySQL tables. I would like to modify it by pulling in some data from a third MySQL table called "comment." In the HTML table below, "title" is a field in the MySQL table "submission." Every "title" has a corresponding "submissionid" field. The field "submissionid" is also found in the "comment" MySQL table. In the HTML table below, I would like "countComments" to equal the number of times a field called "commentid" appears in the MySQL table "comment" for any given "submissionid," where the "submissionid" is the same in both the "submission" and "comment" tables, and where the "submissionid" corresponds to the "title" being used. Here's the catch: if there is no row in the MySQL table "comment" that corresponds with the "submissionid" being used for "table", I would like "countComments" to equal to zero. How can I do this? Thanks in advance, John $sqlStr = "SELECT s.loginid, s.title, s.url, s.displayurl, l.username FROM submission AS s, login AS l WHERE s.loginid = l.loginid ORDER BY s.datesubmitted DESC LIMIT 10"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec\">"; while ($row = mysql_fetch_array($result)) { echo '<tr>'; echo '<td class="sitename1"><a href="http://www.'.$row["url"].'">'.$row["title"].'</a></td>'; echo '</tr>'; echo '<tr>'; echo '<td class="sitename2"><a href="http://www...com/sandbox/members/index.php?profile='.$row["username"].'">'.$row["username"].'</a><a href="http://www...com/sandbox/comments/index.php?submission='.$row["title"].'">'.$row["countComments"].'</a></td>'; echo '</tr>'; } echo "</table>";

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