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  • Automatic database schema generation and migration with Perl

    - by pistacchio
    In Ror or Django or web2py you can "describe" a database (as a set of classes that remaps to tables) and the framework (having being provided with a connection string to the desired database) generates the tables, fields, relations and in the case of RoR and web2py it also keeps it up-to-date (eg, removing a class drops the table, adding a property to the class triggers an "alter table add" etc). Is there any Perl module that does the same? Eg, it takes the YAML/XML/JSON description of a database as input and modifies/generates the database schema accordingly?

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  • Working with foreigh keys - cannot insert

    - by Industrial
    Hi everyone! Doing my first tryouts with foreign keys in a mySQL database and are trying to do a insert, that fails for this reason: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails Does this mean that foreign keys restrict INSERTS as well as DELETES and/or UPDATES on each table that is enforced with foreign keys relations? Thanks!

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  • .NET: Writing DataAccess dll

    - by RedsDevils
    I would like to write all data relations processes (general functions regarding with DataAccess via .NET) in dll and I want to use it repeatedly. What kinds of functions should have in that dll? Some want to use Stored Procedures , Some with Statements. Can you all suggest me? Please guide me! Thanks all!

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  • primitives of a programming language

    - by Tim
    Hi, Which do the concepts control flow, data type, statement, expression and operation belong to? Syntax or semantics? What is the relation between control flow, data type, statement, expression, operation, function, ...? How a program is built from these primitives level by level? I would like to understand these primitive concepts and their relations in order to figure out what aspects of a new language should one learn. Thanks and regards!

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  • .NET: Wrinting DataAccess dll

    - by RedsDevils
    I would like to write all data relations processes (general functions regarding with DataAccess via .NET) in dll and I wanna use it repeatedly. What kinds of functions should have in that dll? Some want to use Storedprocedures , Some with Statemets. Can you all suggest me? Please guide me! Thanks all!

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  • iPhone UITextView position relative

    - by xenep
    Hi, i got a news page (a view) at my application and it has news' image and text. Text is in a UITextView and i want my text to start next to image and when the image ends continue from the down of the image, like the text is surrounding the image. i tried autoResizingMask but as i ve understood it is for the relations between subview and superview so it didnt work. Is there any way to do it ? Thanx in advance

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  • same table, 1 field to 2 field query

    - by edib
    I have 2 tables: 1st holds employees (of ones in any position) and the 2nd holds manager employee relations with id numbers. I want to write a query like 1st field: name(employee), 2nd field: name(manager) How can I do that?

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  • Hibernate + Spring : cascade deletion ignoring non-nullable constraints

    - by E.Benoît
    Hello, I seem to be having one weird problem with some Hibernate data classes. In a very specific case, deleting an object should fail due to existing, non-nullable relations - however it does not. The strangest part is that a few other classes related to the same definition behave appropriately. I'm using HSQLDB 1.8.0.10, Hibernate 3.5.0 (final) and Spring 3.0.2. The Hibernate properties are set so that batch updates are disabled. The class whose instances are being deleted is: @Entity( name = "users.Credentials" ) @Table( name = "credentials" , schema = "users" ) public class Credentials extends ModelBase { private static final long serialVersionUID = 1L; /* Some basic fields here */ /** Administrator credentials, if any */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public AdminCredentials adminCredentials; /** Active account data */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public Account activeAccount; /* Some more reverse relations here */ } (ModelBase is a class that simply declares a Long field named "id" as being automatically generated) The Account class, which is one for which constraints work, looks like this: @Entity( name = "users.Account" ) @Table( name = "accounts" , schema = "users" ) public class Account extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials the account is linked to */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } And here is the AdminCredentials class, for which the constraints are ignored. @Entity( name = "admin.Credentials" ) @Table( name = "admin_credentials" , schema = "admin" ) public class AdminCredentials extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials linked with an administrative account */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } The code that attempts to delete the Credentials instances is: try { if ( account.validationKey != null ) { this.hTemplate.delete( account.validationKey ); } this.hTemplate.delete( account.languageSetting ); this.hTemplate.delete( account ); } catch ( DataIntegrityViolationException e ) { return false; } Where hTemplate is a HibernateTemplate instance provided by Spring, its flush mode having been set to EAGER. In the conditions shown above, the deletion will fail if there is an Account instance that refers to the Credentials instance being deleted, which is the expected behaviour. However, an AdminCredentials instance will be ignored, the deletion will succeed, leaving an invalid AdminCredentials instance behind (trying to refresh that instance causes an error because the Credentials instance no longer exists). I have tried moving the AdminCredentials table from the admin DB schema to the users DB schema. Strangely enough, a deletion-related error is then triggered, but not in the deletion code - it is triggered at the next query involving the table, seemingly ignoring the flush mode setting. I've been trying to understand this for hours and I must admit I'm just as clueless now as I was then.

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  • Database that consumes less disk space

    - by Hugo Palma
    I'm looking at solutions to store a massive quantity of information consuming the less possible disk space. The information structure is very simple and the queries will also be very simple. I've looked at solutions like Apache Cassandra and relations databases but couldn't find a comparison where disk usage is mentioned. Any ideas on this would be great.

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  • Django filter bool not iterable

    - by dana
    I want to filter all Relation Objects where (relation= following relation in a virtual community) the date one has initiated the following is in the past, related to the moment now. The following declaration seems to be wrong, as a bool object is not iterable. Is there another way to do that? d = Relations.objects.filter(date_follow < datetime.now())

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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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  • Subsonic 2.2 and SQL CE

    - by Giuseppe
    Hi, anybody use Subsonic with SQL Server CE 3.5 ? I try but get an error with Substage 2.2, error talking about PK_TABLE. My tables have primary keys and relations. Can someone help me ? By, Giuseppe.

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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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  • database is normalized but the following is a problem please help

    - by user287745
    but the prob is there are relations ships which are so huge that after normalizing they have like a 20 primary keys( composite keys) which are really foreign keys but have to be declared as primary keys to identify the relationship uniquely. so please help? is it correct and i apologize to the expert community for not accepting answers, i was not aware that accepting is possible, the TICK MARK is that visible :-)

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  • Generating db schema from c# class

    - by Niran
    Hi, Is there any other method than nHibernate by wich we can generate db schema from class definition? My classes arn't that complex etc (few one-to-many relations). However I would like to just be able to save my objects in db and recreate schema if needed. I am stuck with .NET 2.0. I am not that particular about performance for this project, I am just lazy to create tables and write save/load code and deel with nHibernate xml. Thanks

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  • Hbase and 1- Many Relation

    - by Shuja
    Hi All I have one question which can be best described by the following scenario. Suppose I have three tables BaseCategory,Category and products. If i am thinking in terms of RDBMS then the relationship amoung these tables are 1- One BaseCategory has Many categories 2- One Category has Many Products. Now i am thinking to convert it into HBase. can anybody help me how to map these relations into HBase?

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  • Scaffold is ignoring class file in CakePHP

    - by JoseMarmolejos
    Hi, when using scaffolding on a controller the views render fine and the app even attempts to insert the data; the problem is that the scaffold is completely ignoring the relations I'm defining in my model class, in fact it's ignoring the class entirely as I can delete the file and the controller still scaffolds and render the crud from the table. Has this ever happened to you?

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  • How to limit manytomanyfields on a model ?

    - by Tom
    I would like to check that I get not more than 3 relations set on a manytomanyfield. I tried on the clean method to do this : if self.tags.count()>3: raise ValidationError(_(u'You cannot add more than 3 tags')) But self.tags returns not the current updates... only saved objects. Do you have an idea to access to them ? Thanks

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  • need a project design tool

    - by santosh
    I am looking for simple and easy to use tools through which I can get project's visual picture of folder/file tree stucture , its classes, functions and objects, relations between classes and files.

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  • Methodology for a Rails app

    - by Aaron Vegh
    I'm undertaking a rather large conversion from a legacy database-driven Windows app to a Rails app. Because of the large number of forms and database tables involved, I want to make sure I've got the right methodology before getting too far. My chief concern is minimizing the amount of code I have to write. There are many models that interact together, and I want to make sure I'm using them correctly. Here's a simplified set of models: class Patient < ActiveRecord::Base has_many :PatientAddresses has_many :PatientFileStatuses end class PatientAddress < ActiveRecord::Base belongs_to :Patient end class PatientFileStatus < ActiveRecord::Base belongs_to :Patient end The controller determines if there's a Patient selected; everything else is based on that. In the view, I will be needing data from each of these models. But it seems like I have to write an instance variable in my controller for every attribute that I want to use. So I start writing code like this: @patient = Patient.find(session[:patient]) @patient_addresses = @patient.PatientAddresses @patient_file_statuses = @patient.PatientFileStatuses @enrollment_received_when = @patient_file_statuses[0].EnrollmentReceivedWhen @consent_received = @patient_file_statuses[0].ConsentReceived @consent_received_when = @patient_file_statuses[0].ConsentReceivedWhen The first three lines grab the Patient model and its relations. The next three lines are examples of my providing values to the view from one of those relations. The view has a combination of text fields and select fields to show the data above. For example: <%= select("patientfilestatus", "ConsentReceived", {"val1"="val1", "val2"="val2", "Written"="Written"}, :include_blank=true )% <%= calendar_date_select_tag "patient_file_statuses[EnrollmentReceivedWhen]", @enrollment_complete_when, :popup=:force % (BTW, the select tag isn't really working; I think I have to use collection_select?) My questions are: Do I have to manually declare the value of every instance variable in the controller, or can/should I do it within the view? What is the proper technique for displaying a select tag for data that's not the primary model? When I go to save changes to this form, will I have to manually pick out the attributes for each model and save them individually? Or is there a way to name the fields such that ActiveRecord does the right thing? Thanks in advance, Aaron.

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