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  • Best datastructure for this relationship...

    - by Travis
    I have a question about database 'style'. I need a method of storing user accounts. Some users "own" other user accounts (sub-accounts). However not all user accounts are owned, just some. Is it best to represent this using a table structure like so... TABLE accounts ( ID ownerID -> ID name ) ...even though there will be some NULL values in the ownerID column for accounts that do not have an owner. Or would it be stylistically preferable to have two tables, like so. TABLE accounts ( ID name ) TABLE ownedAccounts ( accountID -> accounts(ID) ownerID -> accounts(ID) ) Thanks for the advice.

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  • How to get rid of multiple linux versions in grub boot menu

    - by Silver Light
    I've been using dual boot on my PC for some time now, to use Ubuntu along side with Windows 7. One very disturbing thing happens, when Ubuntu linux core gets updated (this happens once in a while). They are added as options to the grub menu so, my boot menu now looks like this: Ubuntu, with linux 2.6.35-27 generic Ubuntu, with linux 2.6.35-27 generic (recovery mode) Ubuntu, with linux 2.6.35-25 generic Ubuntu, with linux 2.6.35-25 generic (recovery mode) Ubuntu, with linux 2.6.35-24 generic Ubuntu, with linux 2.6.35-24 generic (recovery mode) Ubuntu, with linux 2.6.35-22 generic Ubuntu, with linux 2.6.35-22 generic (recovery mode) Memory test Windows 7 This gets very annoying, because I want to load windows by default, but after every update it shifts down and I have to go to grub config and change the default option. My question: How to get rid of older versions of linux in the grub menu and leave only the newest one?

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  • NHibernate - Saving simple parent-child relationship generates unnecessary selects with assigned id

    - by Alice
    Entities: public class Parent { virtual public long Id { get; set; } virtual public string Description { get; set; } virtual public ICollection<Child> Children { get; set; } } public class Child { virtual public long Id { get; set; } virtual public string Description { get; set; } virtual public Parent Parent { get; set; } } Mappings: public class ParentMap : ClassMap<Parent> { public ParentMap() { Id(x => x.Id).GeneratedBy.Assigned(); Map(x => x.Description); HasMany(x => x.Children) .AsSet() .Inverse() .Cascade.AllDeleteOrphan(); } } public class ChildMap : ClassMap<Child> { public ChildMap() { Id(x => x.Id).GeneratedBy.Assigned(); Map(x => x.Description); References(x => x.Parent) .Not.Nullable() .Cascade.All(); } } and using (var session = sessionFactory.OpenSession()) using (var transaction = session.BeginTransaction()) { var parent = new Parent { Id = 1 }; parent.Children = new HashSet<Child>(); var child1 = new Child { Id = 2, Parent = parent }; var child2 = new Child { Id = 3, Parent = parent }; parent.Children.Add(child1); parent.Children.Add(child2); session.Save(parent); transaction.Commit(); } this codes generates following sql NHibernate: SELECT child_.Id, child_.Description as Descript2_0_, child_.Parent_id as Parent3_0_ FROM [Child] child_ WHERE child_.Id=@p0;@p0 = 2 [Type: Int64 (0)] NHibernate: SELECT child_.Id, child_.Description as Descript2_0_, child_.Parent_id as Parent3_0_ FROM [Child] child_ WHERE child_.Id=@p0;@p0 = 3 [Type: Int64 (0)] NHibernate: INSERT INTO [Parent] (Description, Id) VALUES (@p0, @p1);@p0 = NULL[Type: String (4000)], @p1 = 1 [Type: Int64 (0)] NHibernate: INSERT INTO [Child] (Description, Parent_id, Id) VALUES (@p0, @p1, @p2);@p0 = NULL [Type: String (4000)], @p1 = 1 [Type: Int64 (0)], @p2 = 2 [Type:Int64 (0)] NHibernate: INSERT INTO [Child] (Description, Parent_id, Id) VALUES (@p0, @p1, @p2);@p0 = NULL [Type: String (4000)], @p1 = 1 [Type: Int64 (0)], @p2 = 3 [Type:Int64 (0)] Why are these two selects generated and how can I remove it?

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  • How to create relationship mapping via Entity framework

    - by James
    I have following domain model: User { int Id; } City { int Id; } UserCity { int UserId, int CityId, dateTime StartDate } In the function where I have to attach a user to a city, the following code is working for me: UserCity uc = new UserCity(); //This is a db hit uc.User = MyEntityFrameworkDBContext.User.FirstOrDefault(u => u.ID == currentUserId); //this is a db hit uc.City = MyEntityFrameworkDBContext.City.FirstOrDefault(c => c.ID == currentCityId); uc.StartDate = userCityStartDate; //this is a db hit MyEntityFrameworkDBContext.SaveChanges(); Is there any way I can create relationships with just one single DB hit? The first two db hits are not required, actually.

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  • why does perl allow mutually "use" relationship between modules

    - by Haiyuan Zhang
    let's say there two modules mutualy use each othe as: package a; use b; sub p {} 1; package b; use a; 1; I think symatically it's wrong to wrote code like the above code, cus the two modules will endlessly copy each other's code to themselves...but I can successfully run the following code, which makes me very surprised. so could any of you explain all of this to me? #! /usr/bin/perl use a; a->p();

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  • Entity Framework one-to-one relationship mapping flattened in code

    - by Josh Close
    I have a table structure like so. Address: AddressId int not null primary key identity ...more columns AddressContinental: AddressId int not null primary key identity foreign key to pk of Address County State AddressInternational: AddressId int not null primary key identity foreign key to pk of Address ProvinceRegion I don't have control over schema, this is just the way it is. Now, what I want to do is have a single Address object. public class Address { public int AddressId { get; set; } public County County { get; set; } public State State { get; set } public ProvinceRegion { get; set; } } I want to have EF pull it out of the database as a single entity. When saving, I want to save the single entity and have EF know to split it into the three tables. How would I map this in EF 4.1 Code First? I've been searching around and haven't found anything that meets my case yet. UPDATE An address record will have a record in Address and one in either AddressContinental or AddressInternational, but not both.

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  • Implementing Unowned relationship Google App Engine

    - by nwallman
    My question is more of a best practices question on how to implement unowned relationships with Google App Engine. I am using JDO to do my persistence and like recommended in the google docs I'm persisting my list of unowned relationships like so: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class User implements Serializable, UserDetails { ... @Persistent private List<Key> groups; ... } Now I came across my predicament when I went to query that list of objects using they Key object. So when I get my list of group keys in order to actually return a list of Group objects I have to do a look up on that key to get the object. My question is what is the recommended way of doing a unowned look up on a model object? Should I have an instance of the PersistanceManagerFactory on my Model object so I can do a lookup? Should I have an instance of my GroupDAO object on my Model object so I can do a look up? Should I have a Utility to do this type of lookup? I'm new to this so I just want to know which is the best way to do this. Thanks.

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  • Tables relationship in Cakephp

    - by kwokwai
    Hi all, I am new to Models structure in Cakephp. A few weeks ago I came across a tutorial in which the author got three tables in Database: Table A: {ID, Description, IsActive} Table B: {ID, TableA_ID, Description, CreationDate, ModifiedDate} Table A_B: {ID, TableA_ID, TableB_ID} The author of the tutorial said that the third table (Table A_B) is needed to run in CakePHP. I don't understand. Is there any specific documentation in CakePHP that I can refer to? I know there is a CookBook in Cakephp web site, but I couldn't find the relevant infromation.

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  • Cakephp: Extend search capability to hasMany Relationship

    - by Chris
    I have two models: Car hasMany Passengers Passenger belongsTo Car I want to implement a search using Cake Search. The user should input a number and the searchengine should return all cars that have less than this number passengers. In my search form: echo $form->input('passengers', array('label' => 'Passengers', 'div' => false)); In my Car model: public $filterArgs = array( array('name' => 'passengers', 'type' => 'int'), ); In the controller: public $presetVars = array( array('field' => 'passengers', 'type' => 'int') } I thought of adding a function to the model that returns the number of passengers: function countPassengers(){ return(count($this->Car->Passenger)); //Not sure if this works } And how to I implement this search criteria?: return all Cars where countPassengers()<passenger

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  • iOS: how to understand the role of rootviewcontroller and its relationship with other objects

    - by Anthony Kong
    I have created a UISplitViewController based iOS app in XCode 3.2.5 Below is a screen shot of Interface builder showing the rootviewcontroller and how it is linked to other objects. Being a beginner myself, I do not understand: 1) What is the role of the rootviewcontroller? Searched the documentation but what I found did not answer this question. 2) I thought a IBOutlet should only link to one corresponding object. Why in this case the rootviewcontroller is linked to two?

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  • JDO architecture: One to many relationship and cascading deleting

    - by user361897
    I’m new to object oriented database designs and I’m trying to understand how I should be structuring my classes in JDO for google app engine, particularly one to many relationships. Let’s say I’m building a structure for a department store where there are many departments, and each department has many products. So I’d want to have a class called Department, with a variable that is a list of a Product class. @PersistenceCapable public class Department { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String deptID; @Persistent private String departmentName; @Persistent private List<Product>; } @PersistenceCapable public class Product { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String productID; @Persistent private String productName; } But one Product can be in more than one Department (like a battery could be in electronics and household supplies). So the next question is, how do I not duplicate data in the OOD world and have only one copy of product data in numerous departments? And the next question is, let’s say I delete out a particular product, how do each of the departments know it was deleted?

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  • inheriting scope from a has_many relationship

    - by hb922
    I am using ruby on rails 3.1 and have 2 models, an event and a group. Each event has_many groups, but has to have at least one "master" group, where the column :is_master = true Class Group < ActiveRecord::Base has_many :users belongs_to :event scope :master, where (:is_master => true) end Class Event< ActiveRecord::Base has_many :groups def master_group groups.master end end I want to be able to default all properties of the master group to the event, so for example, event.users.count should be the same as event.master_group.users.count. Is there any way to do something like this? Can I do a has_many :through = master_group? Am I approaching this the wrong way? Thanks!

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  • Hibernate mapping to manage bidirectional relationship using intermediate table

    - by shikarishambu
    I have an object hierarchy that is as follows. Party inherited by Organization and Person Organization inherited by Customer, Vendor Person inherited by Contact In the database I have the following tables Party, Customer, Vendor, Contact. All of them have a corresponding row in Party table. Contact belongs to either Vendor or Customer. I have a field on the Contact table for org_party_id. However, since the organization can be either a Customer or Vendor I need to be able to look at different tables. Is there a way to map this in hibernate? Or, a better way to manage it in DB/ hibernate?

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  • jpa relationship-Google app engine

    - by megala
    I created two tables in google appengine datastore using JPA. Table1: *groupname pk *groupid *groupdesc *emailper Table2: *groupname *memberid *membername My constraint is if i enter data into table2 it check whether group already exists or not in table.If exists than only it store the data into table .How to solve this?

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  • Do I need to manually create indexes for a DBIx::Class belongs_to relationship

    - by Dancrumb
    I'm using the DBIx::Class modules for an ORM approach to an application I have. I'm having some problems with my relationships. I have the following package MySchema::Result::ClusterIP; use strict; use warnings; use base qw/DBIx::Class::Core/; our $VERSION = '1.0'; __PACKAGE__->load_components(qw/InflateColumn::Object::Enum Core/); __PACKAGE__->table('cluster_ip'); __PACKAGE__->add_columns( # Columns here ); __PACKAGE__->set_primary_key('objkey'); __PACKAGE__->belongs_to( 'configuration' => 'MySchema::Result::Configuration', 'config_key'); __PACKAGE__->belongs_to( 'cluster' => 'MySchema::Result::Cluster', { 'foreign.config_key' => 'self.config_key', 'foreign.id' => 'self.cluster_id' } ); As well as package MySchema::Result::Cluster; use strict; use warnings; use base qw/DBIx::Class::Core/; our $VERSION = '1.0'; __PACKAGE__->load_components(qw/InflateColumn::Object::Enum Core/); __PACKAGE__->table('cluster'); __PACKAGE__->add_columns( # Columns here ); __PACKAGE__->set_primary_key('objkey'); __PACKAGE__->belongs_to( 'configuration' => 'MySchema::Result::Configuration', 'config_key'); __PACKAGE__->has_many('cluster_ip' => 'MySchema::Result::ClusterIP', { 'foreign.config_key' => 'self.config_key', 'foreign.cluster_id' => 'self.id' }); There are a couple of other modules, but I don't believe that they are relevant. When I attempt to deploy this schema, I get the following error: DBIx::Class::Schema::deploy(): DBI Exception: DBD::mysql::db do failed: Can't create table 'test.cluster_ip' (errno: 150) [ for Statement "CREATE TABLE `cluster_ip` ( `objkey` smallint(5) unsigned NOT NULL auto_increment, `config_key` smallint(5) unsigned NOT NULL, `cluster_id` char(16) NOT NULL, INDEX `cluster_ip_idx_config_key_cluster_id` (`config_key`, `cluster_id`), INDEX `cluster_ip_idx_config_key` (`config_key`), PRIMARY KEY (`objkey`), CONSTRAINT `cluster_ip_fk_config_key_cluster_id` FOREIGN KEY (`config_key`, `cluster_id`) REFERENCES `cluster` (`config_key`, `id`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `cluster_ip_fk_config_key` FOREIGN KEY (`config_key`) REFERENCES `configuration` (`config_key`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB"] at test_deploy.pl line 18 (running "CREATE TABLE `cluster_ip` ( `objkey` smallint(5) unsigned NOT NULL auto_increment, `config_key` smallint(5) unsigned NOT NULL, `cluster_id` char(16) NOT NULL, INDEX `cluster_ip_idx_config_key_cluster_id` (`config_key`, `cluster_id`), INDEX `cluster_ip_idx_config_key` (`config_key`), PRIMARY KEY (`objkey`), CONSTRAINT `cluster_ip_fk_config_key_cluster_id` FOREIGN KEY (`config_key`, `cluster_id`) REFERENC ES `cluster` (`config_key`, `id`) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT `cluster_ip_fk_config_key` FOREIGN KEY (`config_key`) REFERENCES `configuration` (`conf ig_key`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB") at test_deploy.pl line 18 From what I can tell, MySQL is complaining about the FOREIGN KEY constraint, in particular, the REFERENCE to (config_key, id) in the cluster table. From my reading of the MySQL documentation, this seems like a reasonable complaint, especially in regards to the third bullet point on this doc page. Here's my question. Am I missing something in the DBIx::Class module? I realize that I could explicitly create the necessary index to match up with this foreign key constraint, but that seems to be repetitive work. Is there something I should be doing to make this occur implicitly?

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  • multiple-to-one relationship mysql, submissions

    - by Yulia
    Hello, I have the following problem. Basically I have a form with an option to submit up to 3 images. Right now, after each submission it creates 3 records for album table and 3 records for images. I need it to be one record for album and 3 for images, plus to link images to the album. I hope it all makes sense... Here is my structure. TABLE `albums` ( `id` int(11) NOT NULL auto_increment, `title` varchar(50) NOT NULL, `fullname` varchar(40) NOT NULL, `email` varchar(100) NOT NULL, `created_at` datetime NOT NULL, `theme_id` int(11) NOT NULL, `description` int(11) NOT NULL, `vote_cache` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=20 ; TABLE `images` ( `id` int(11) NOT NULL auto_increment, `album_id` int(11) NOT NULL, `name` varchar(30) NOT NULL, and my code function create_album($params) { db_connect(); $query = sprintf("INSERT INTO albums set albums.title = '%s', albums.email = '%s', albums.discuss_url = '%s', albums.theme_id = '%s', albums.fullname = '%s', albums.description = '%s', created_at = NOW()", mysql_real_escape_string($params['title']), mysql_real_escape_string($params['email']), mysql_real_escape_string($params['theme_id']), mysql_real_escape_string($params['fullname']), mysql_real_escape_string($params['description']) ); $result = mysql_query($query); if(!$result) { return false; } $album_id = mysql_insert_id(); return $album_id; } if(!is_uploaded_file($_FILES['userfile']['tmp_name'][$i])) { $warning = 'No file uploaded'; } elseif is_valid_file_size($_FILES['userfile']['size'][$i])) { $_POST['album']['theme_id'] = $theme['id']; create_album($_POST['album']); mysql_query("INSERT INTO images(name) VALUES('$newName')"); copy($_FILES['userfile']['tmp_name'][$i], './photos/'.$original_dir.'/' .$newName.'.jpg');

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  • SQL Server 2008: The columns in table do not match an existing primary key or unique constraint

    - by 109221793
    Hi guys, I need to make some changes to a SQL Server 2008 database. This requires the creation of a new table, and inserting a foreign key in the new table that references the Primary key of an already existing table. So I want to set up a relationship between my new tblTwo, which references the primary key of tblOne. However when I tried to do this (through SQL Server Management Studio) I got the following error: The columns in table 'tblOne' do not match an existing primary key or UNIQUE constraint I'm not really sure what this means, and I was wondering if there was any way around it?

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  • Flash relationship map

    - by John
    Hi, Does anyone know any Flash fla's which are out there and free which do something similar to http://audiomap.tuneglue.net/ (you have to type in a search term to see it in action). What I'm after is the flash to create the node in the middle which expands out into children and then each of those children can be expanded out into more children, etc. while keeping their distance from one another so as to not overlap. I'd like it so that if you clicked on a node to expand it, it would shoot off to a web site and get an xml feed which could then be used to create the children. Thanks

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  • Defining relationship in value objects using Hibernate

    - by kate
    Hi, We have three tables .We need to get data from these tables based upon particular conditions. Like if TableA.columv=TableB.columc=tableC.column then get data. We are using value objects to map Objects to relations. Question is how to maintain these relation ships in value objects. And how to retrieve data from it. We have one value object per table.

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  • Insert Into Two SQL Tables From XML Maintaining Relationship

    - by Thx
    I am looking to insert records from xml into two different tables. For example <Root> <A> <AValue>1</AValue> <Children> <B> <BValue>2</BValue> </B> </Children> </A> </Root> Would insert a record into table A AID AValue # 1 also insert a record into table B BID AID BValue # #(Same as AID Above) 2 I have this DECLARE @idoc INT DECLARE @doc NVARCHAR(MAX) SET @doc = ' <Root> <A> <AValue>1</AValue> <Children> <B> <BValue>2</BValue> </B> </Children> </A> </Root> ' EXEC sp_xml_preparedocument @idoc OUTPUT, @doc CREATE TABLE #A ( AID INT IDENTITY(1, 1) , AValue INT ) INSERT INTO #A SELECT * FROM OPENXML (@idoc, '/Root/A',2) WITH (AValue INT ) CREATE TABLE #B ( BID INT IDENTITY(1, 1) , AID INT , BValue INT ) INSERT INTO #B SELECT * FROM OPENXML (@idoc, '/Root/A/Children/B',2) WITH ( AID INT, BValue INT ) SELECT * FROM #A SELECT * FROM #B DROP TABLE #A DROP TABLE #B Thanks!

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  • Core Data not-reverse relationship subquery

    - by user561485
    Hi, I have the following entities in CoreData: Village - villageID Bookmark - (relation) village There are multiple villages with each an unique villageID. I have a entity Bookmark which only has a relation to a Village entity; it isn't possible to make a reverse relation. Now I would like to get the village entities where there exists a Bookmark relation. I've red something about subqueries, but I can't get it right for this situation. It must be something like: Village.villageID IN (Bookmark.village.villageID) It isn't possible to get first all the Bookmarks and then loop to get all the Villages, because of the design of the framework. Can this be done in CoreData (I presume the answer is "Yes, of course!") and how?

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  • Yii Many_Many Relationship and Form

    - by Thorpe Obazee
    // Post model return array( 'categories' => array(self::HAS_MANY, 'Category', 'posts_categories(post_id, category_id)') ); I already have the setup of tables posts id, title, content categories id, name posts_categories post_id, category_i The problem I have is that I am getting an error when creating this form: <?php $form=$this->beginWidget('CActiveForm', array( 'id'=>'post-form', 'enableAjaxValidation'=>false, )); ?> <p class="note">Fields with <span class="required">*</span> are required.</p> <?php echo $form->errorSummary($model); ?> <div class="row"> <?php echo $form->labelEx($model,'title'); ?> <?php echo $form->textField($model,'title',array('size'=>60,'maxlength'=>255)); ?> <?php echo $form->error($model,'title'); ?> </div> <div class="row"> <?php echo $form->labelEx($model,'uri'); ?> <?php echo $form->textField($model,'uri',array('size'=>60,'maxlength'=>255)); ?> <?php echo $form->error($model,'uri'); ?> </div> <div class="row"> <?php echo $form->labelEx($model,'content'); ?> <?php echo $form->textArea($model,'content',array('rows'=>6, 'cols'=>50)); ?> <?php echo $form->error($model,'content'); ?> </div> <div class="row"> <?php // echo $form->labelEx($model,'content'); ?> <?php echo CHtml::activeDropDownList($model,'category_id', CHtml::listData(Category::model()->findAll(), 'id', 'name')); ?> <?php // echo $form->error($model,'content'); ?> </div> <div class="row buttons"> <?php echo CHtml::submitButton($model->isNewRecord ? 'Create' : 'Save'); ?> </div> <?php $this->endWidget(); ?> The error is: Property "Post.category_id" is not defined. I am quite confused. What should I be doing to correct this?

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