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  • Why do static Create methods exist?

    - by GeReV
    I was wondering, why do static Create methods exist? For instance, why use this code: System.Xml.XmlReader reader = System.Xml.XmlReader.Create(inputUri); over this code: System.Xml.XmlReader reader = new System.Xml.XmlReader(inputUri); I cannot find the rationale for using one over the other, and can't find any relation between classes who use this construct over the other. Can anyone shed some light on this?

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  • What will be best strategy for designing database for a magazine online?

    - by Kaveh
    Hello; I have design a magazine online and worry that is it the best approch or at least a good approch or no,the magazine contains articles+news in all subjects, i have one table for both articles+news ,but i would like to know that is this good or i must separate articles and news (it is clear that beside the main table there are several tables for categories ,tags,and photos and tables for relation between these tables)? Thanks

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  • How to Configure and run DataBase Mail in SQL Server

    - by Nasser Hajloo
    How to enable and run Database Mail in SQL Server 2008 . I know that it need Enabling Service Broker Configuring SMTP (a Mail server is needed) Using Configuration Storeprocedure. I don't know what's the relation between application and dataBase mail. Actually How to enable Database mail for a RollBack and Commit Transaction ? (not for all SP , just for some of them)

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  • Facebook database design?

    - by Marin
    I have always wondered how Facebook designed the friend <- user relation. I figure the user table is something like this: user_email PK user_id PK password I figure the table with user's data (sex, age etc connected via user email I would assume). How does it connect all the friends to this user? Something like this? user_id friend_id_1 friend_id_2 friend_id_3 friend_id_N Probably not. Because the number of users is unknown and will expand.

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  • Linq to Entities and outer joins issue

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer joins instead of inner joins? It relation was many to 0..1. There's referential constraint on DB itself, that ensures there's a record in the right table, so inner join should be used instead. Is it possible to write LINQ in a way so they will translate to inner joins rather than left outer joins. It would speed query execution a lot.

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  • Tables as relations in ER diagrams

    - by Richard Mar.
    Assume I have the following tables (**bold** - primary key, *italics* - foreign key): patient(**patient_id**, name) disease(**disease_id**, name) patient_disease(**p_d_id**, *patient_id*, *disease,_id* ) I want to draw the ER diagram for this. My idea is to make two entities, one for patient and one for disease, then make a n-to-n relation between them, with p_d_id as its attribute. Is that how it's supposed to be?

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  • Hibernate persist order

    - by user213855
    Hi there! I have a question about how Hibernate persists entity relations. Let's say I have an entity A that has a relation with entity B and another one with entity C. I create an A instance and populate it with new instances of B and C. When I persist A I need C to be persisted previous to B. Is there any way of doing this? Thanks a lot.

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  • UNIQUE Constraints in SQL (MS-SQL)

    - by rockbala
    Why are UNIQUE Constraints needed in database ? Can you provide any examples ? Primary Key is UNIQUE by default... Understandable as they are referred in other tables as Foreign keys... relation is needed to connect them for rdbms platform... but why would one refer to other columns as UNIQUE, what is benefit of doing so ?)

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  • Many-To-Many Query with Linq-To-NHibernate

    - by rjygraham
    Ok guys (and gals), this one has been driving me nuts all night and I'm turning to your collective wisdom for help. I'm using Fluent Nhibernate and Linq-To-NHibernate as my data access story and I have the following simplified DB structure: CREATE TABLE [dbo].[Classes]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [Name] [nvarchar](100) NOT NULL, [StartDate] [datetime2](7) NOT NULL, [EndDate] [datetime2](7) NOT NULL, CONSTRAINT [PK_Classes] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[Sections]( [Id] [bigint] IDENTITY(1,1) NOT NULL, [ClassId] [bigint] NOT NULL, [InternalCode] [varchar](10) NOT NULL, CONSTRAINT [PK_Sections] PRIMARY KEY CLUSTERED ( [Id] ASC ) CREATE TABLE [dbo].[SectionStudents]( [SectionId] [bigint] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, CONSTRAINT [PK_SectionStudents] PRIMARY KEY CLUSTERED ( [SectionId] ASC, [UserId] ASC ) CREATE TABLE [dbo].[aspnet_Users]( [ApplicationId] [uniqueidentifier] NOT NULL, [UserId] [uniqueidentifier] NOT NULL, [UserName] [nvarchar](256) NOT NULL, [LoweredUserName] [nvarchar](256) NOT NULL, [MobileAlias] [nvarchar](16) NULL, [IsAnonymous] [bit] NOT NULL, [LastActivityDate] [datetime] NOT NULL, PRIMARY KEY NONCLUSTERED ( [UserId] ASC ) I omitted the foreign keys for brevity, but essentially this boils down to: A Class can have many Sections. A Section can belong to only 1 Class but can have many Students. A Student (aspnet_Users) can belong to many Sections. I've setup the corresponding Model classes and Fluent NHibernate Mapping classes, all that is working fine. Here's where I'm getting stuck. I need to write a query which will return the sections a student is enrolled in based on the student's UserId and the dates of the class. Here's what I've tried so far: 1. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.First(f => f.UserId == userId) != null select s); 2. var sections = (from s in this.Session.Linq<Sections>() where s.Class.StartDate <= DateTime.UtcNow && s.Class.EndDate > DateTime.UtcNow && s.Students.Where(w => w.UserId == userId).FirstOrDefault().Id == userId select s); Obviously, 2 above will fail miserably if there are no students matching userId for classes the current date between it's start and end dates...but I just wanted to try. The filters for the Class StartDate and EndDate work fine, but the many-to-many relation with Students is proving to be difficult. Everytime I try running the query I get an ArgumentNullException with the message: Value cannot be null. Parameter name: session I've considered going down the path of making the SectionStudents relation a Model class with a reference to Section and a reference to Student instead of a many-to-many. I'd like to avoid that if I can, and I'm not even sure it would work that way. Thanks in advance to anyone who can help. Ryan

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  • Formtastic with Mongoid embedded_in relations

    - by miah
    Is there any quick way to make a form for embeds_many-embedded_in relation? I have the following: class Team include Mongoid::Document field :name, :type => String embeds_many :players end class Player include Mongoid::Document embedded_in :team, :inverse_of => :players field :name, :type => String end I want to create a form for team with embedded editing for players. Seen https://github.com/bowsersenior/formtastic_with_mongoid_tutorial but "TODO" there.

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  • Why does sorted list have to have a key value pair?

    - by clawson
    If I just want a sorted list of just dates, integers, or doubles is it really necessary to have to define a SortedList(of Integer, Integer)? Seems intriguing to me, but may just be trival. I'd prefer just to use a SortedList(of Integer). (This question is in relation to the .Net generic collections)

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  • facebook application error

    - by moustafa
    it needs facebook facepile plugin(http://developers.facebook.com/docs/reference/plugins/facepile). i tried but i am getting this error (The Facebook Connect cross-domain receiver URL (http://static.ak.fbcdn.net/connect/xd_proxy.php#?=&cb=f223d517566e616&origin=http%3A%2F%2Fpromolife.com.au%2Ff3e13728ba8ec8&relation=parent.parent&transport=postmessage) must have the application's Connect URL (http://www.testsite.com.au/) as a prefix. You can configure the Connect URL in the Application Settings Editor.) why do i getting this error please help me.

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  • Using a join model to relate a model to itself

    - by Gabe Hollombe
    I have two models: User MentoringRelationship MentoringRelationship is a join model that has a mentor_id column and a mentee_id column (both of these reference user_ids from the users table). How can I specify a relation called 'mentees' on the User class that will return all of the users mentored by this user, using the MentoringRelationships join table? What relations do we need to declare in the User model and in the MentoringRelationship model?

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  • UNIQUE Constraints in SQL (SQL Server)

    - by rockbala
    Why are UNIQUE Constraints needed in database ? Can you provide any examples ? Primary Key is UNIQUE by default... Understandable as they are referred in other tables as Foreign keys... relation is needed to connect them for rdbms platform... but why would one refer to other columns as UNIQUE, what is benefit of doing so ?)

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  • Remove then Query fails in JPA/Hibernate (deleted entity passed to persist)

    - by Kevin
    I've got a problem with the removal of entities in my JPA application: basically, I do in this EJB Business method: load photo list ; for each photo { //UPDATE remove TagPhoto element from @OneToMany relation //DISPLAY create query involving TagPhoto ... } and this last query always throws an EntityNotFoundException (deleted entity passed to persist: [...TagPhoto#]) I think I understand the meaning of this exception, like a synchronization problem caused by my Remove, but how can I get rid of it?

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  • Swap CSS class on the basis of Scroll Position with Javascript

    - by Alan
    I have followed answer given by CMS in relation to getting a menu to stay in one place on the page whilst you scroll the page as per this original question and it works very well but I also have a number of images on the page where I'm using the jquery fancylink plugin to show an enlarged image on click. The problem is when you then close the fancylink popup and scroll to the top of the page the static DIV then decides to stick to the very top of the page. Any ideas or help would this would be greatly appreciated.

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