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  • Easiest way to rename a model using Django/South?

    - by vaughnkoch
    Hi everyone, I've been hunting for an answer to this on South's site, google, and SO, but couldn't find a simple way to do this. I want to rename a Django model using South. Say you have the following: class Foo(models.Model): name = models.CharField() class FooTwo(models.Model): name = models.CharField() foo = models.ForeignKey(Foo) and you want to convert Foo to Bar, namely class Bar(models.Model): name = models.CharField() class FooTwo(models.Model): name = models.CharField() foo = models.ForeignKey(Bar) To keep it simple, I'm just trying to change the name from Foo to Bar, but ignore the 'foo' member in FooTwo for now. What's the easiest way to do this using South? a) I could probably do a data migration, but that seems pretty involved. b) Write a custom migration, e.g. db.rename_table('city_citystate', 'geo_citystate'), but I'm not sure how to fix the foreign key in this case. c) An easier way that you know? Thanks!

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  • Database Design Question

    - by deniz
    Hi, I am designing a database for a project. I have a table that has 10 columns, most of them are used whenever the table is accessed, and I need to add 3 more rows; View Count Thumbs Up (count) Thumbs Down (Count) which will be used on %90 of the queries when the table is accessed. So, my question is that whether it is better to break the table up and create new table which will have these 3 columns + Foreign ID, or just make it 13 columns and use no joins? Since these columns will be used frequently, I guess adding 3 more columns is better, but if I need to create 10 more columns which will be used %90 of the time, should I add them as well, or create a new table and use joins? I am not sure when to break the table if the columns are used very frequently. Do you have any suggestions? Thanks in advance,

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  • Ruby on Rails and database associations

    - by Marco
    Hi to all, I'm new to the Ruby world, and there is something unclear to me in defining associations between models. The question is: where is the association saved? For example, if i create a Customer model by executing: generate model Customer name:string age:integer and then i create an Order model generate model Order description:text quantity:integer and then i set the association in the following way: class Customer < ActiveRecord::Base has_many :orders end class Order < ActiveRecord::Base belongs_to :customer end I think here is missing something, for example the foreign key between the two entities. How does it handle the associations created with the keywords "has_many" and "belongs_to" ? Thanks

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  • DataMapper: using auto_migrate! with many-to-many dependencies?

    - by pschuegr
    Hi, I'm trying to migrate my app from MySql to Postgresql, using Rails3-pre and the latest DataMapper. I have several models which are related through many-to-many relationships using :through = Resource, which means that DataMapper creates a join table with foreign keys for both models. I can't auto_migrate! these changes, because I keep getting this: ERROR: cannot drop table users because other objects depend on it DETAIL: constraint artist_users_owner_fk on table artist_users depends on table users constraint site_users_owner_fk on table site_users depends on table users HINT: Use DROP ... CASCADE to drop the dependent objects too. I have tried everything I can think of, and thought I had things working when I added :constraint = :skip to the field definition, but I keep getting that error back when I try and run auto_migrate. I thought that :skip meant that it would ignore the dependents, but maybe that only applies for deleting rows and not dropping tables? I should mention that I can run auto_migrate after i nuke the db once, but after that, errors. Any suggestions or advice much appreciated.

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  • SQL? "Show me all the Activities that can be performed by User X."

    - by Casey Fulton
    I'm at my wits end. I've searched like crazy, read plenty of database textbooks and God knows how many online guides, blogs and forums. Can someone put me out of my misery? PseudoSchema Diagram (Warning: although pretty, not in a format even remotely approaching ER diagrams! Primary keys are bold, foreign keys are italics.) Given the above set of tables relating Users to Groups to Privileges, and then a set of Activities that can each require a Privilege to perform, how do you find out this: Show me all the Activities that can be performed by User X. That is: User X is a member of groups G and F; groups G and F correlate to privileges P, Q, R and S; show me all the activities that require privileges either P, Q, R or S. How do you do this?

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  • How to search in this activerecord example?

    - by Horace Ho
    Two models: Invoice :invoice_num string :date datetime . . :disclaimer_num integer (foreign key) Disclaimer :disclaimer_num integer :version integer :body text For each disclaimer there are multiple versions and will be kept in database. This is how I write the search (simplified): scope = Invoice.scoped({ :joins => [:disclaimer] }) scope = scope.scoped :conditions => ["Invoice.invoice_num = ?", "#{params[:num]}"] scope = scope.scoped :conditions => ["Disclaimer.body LIKE ?", "%#{params[:text]}%"] However, the above search will search again all versions of the disclaimer. How can I limit the search to only the last disclaimer (i.e. the version integer is the maximum). Please note: Invoice does not keep the version number. New disclaimers will be added to disclaimer table and keep old versions.

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  • Saving related model objects

    - by iHeartDucks
    I have two related models (one to many) in my django app and When I do something like this ObjBlog = Blog() objBlog.name = 'test blog' objEntry1 = Entry() objEntry1.title = 'Entry one' objEntry2 = Entry() objEntry2.title = 'Entry Two' objBlog.entry_set.add(objEntry1) objBlog.entry_set.add(objEntry2) I get an error which says "null value in column and it violates the foreign key not null constraint". None of my model objects have been saved. Do I have to save the "objBlog" before I could set the entries? I was hoping I could call the save method on objBlog to save it all. NOTE: I am not creating a blog engine and this is just an example.

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  • How to delete refClass record in Doctrine?

    - by terrani
    Hi all! I have many-to-many relations with the following tables. post tag post_tag I created three classes with Doctrine, so I have the following classes as well. BasePost BaseTag BasePostTag in the setUp() method, I defined relations. I like to delete tag record when I delete post record. So I simply put cascade as descirbed on Doctrine document. $this->hasMany("Tag as Tags",array( 'refClass' => 'PostTag', 'local'=>'object_id', 'foreign'=>'tag_id', 'cascade'=> array('delete') )); it works without a problem. My questions is, how do I delete a record from post_tag table? Do I need to create a query myself?

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  • InvalidOperationException sequence contains more than one element even when only one element

    - by user310256
    I have three tables, tblCompany table, tblParts table and a link table between them tblLinkCompanyParts. Since tblLinkCompanyParts is a link table so the columns that it has are LinkCompanyPartID(primary key), CompanyID from tblCompany table and PartID from tblParts as foreign keys. I have tied them up in the dbml file. In code if I write LinkCompanyParts.Parts (where LinkCompanyParts is an object of the tblLinkCompanyParts type) to get to the corresponding Part object I get the "InvalidOperationException: Sequence constains more than one element". I have looked at the data in the database and there is only one Parts record associated with the LinkCompanyPartID. The stack trace reads like at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source) at System.Data.Linq.EntityRef`1.get_Entity() at ... I read about SingleOrDefault vs FirstOrDefault but since the link table should have a one-one mapping therefore I think SingleOrDefault should work and besides "SingleOrDefault" statement is being generated behind the scenes in the designer.cs file at the following line return this._Part.Entity; Any ideas?

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  • Finding final/effective web.config values (from inherited configurations)

    - by gregmac
    Are there any apps that can show the final configuration as applied to a particular application directory? What I'm picturing is something along the lines of FireBug's CSS viewer. Basically, it should show the equivalent single web.config file (as if you only had one), with all the values that apply to the directory in question, with each element (or even attribute) annotated with its source (the real .config file it came from). This would greatly help deploying applications into foreign environments (eg, customer sites) where they sometimes have strange configs, that add in global includes (eg, they put the include in machine.config, instead of the web.config for that app) or have allowOverride=false, etc.

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  • Ruby on Rails: building a model with an attribute not in the database?

    - by randombits
    I have a model that sets one of its attributes based off of a form parameter that a user submits. The model is a child resource to a parent resource Home. A hypothetical example is the following: A class Person has an age attribute. The user submits a birthdate as an HTTP POST parameter and from that, I need to derive the age of the user. So I'd do something like this: @home.people.build(:name => params[:name], :birthdate => params[:birthdate]) Rails would barf on that for obvious reasons, complaining it doesn't know what the attribute birthdate is. What's the proper way of going about this? Is it possible to use the build constructor with the supplied solution so that my foreign key relations are also setup properly? If not, what's a better way to work around this problem?

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  • ValueError: too many values to unpack in a tuple

    - by falosi
    Please put some light on why am getting a too many to unpack (ValueError in my for loop).Have tried deb naislist = [('CONTROL FILE', '0', '0', '0'), ('REDO LOG', '0', '0', '0'), ('ARCHIVED LOG', '.69', '.59', '3'), ('BACKUP PIECE', '46.54', '0', '192'), ('IMAGE COPY', '0', '0', '0'), ('FLASHBACK LOG', '10.15', '6.31', '82'), ('FOREIGN ARCHIVED LOG', '0', '0', '0')] print "size of naislist is ",len((naislist)) heading = ('MAIN MENU', 'LEVELS', 'LEVEL2', 'LEVEL3') rearrange = dict(zip((0, 1, 2, 3), (len(str(x)) for x in heading))) for tu, x in naislist: rearrange.update((i, max(rearrange[i], len(str(el)))) for i, el in enumerate(tu)) rearrange[4] = max(rearrange[4], len(str(x))) forkit = '|'. join('%%-%ss' % rearrange[i] for i in xrange(0, 4)) print '\n'.join((forkit % heading, '-|-'.join(rearrange[i] * '-' for i in xrange(4)), '\n'.join(forkit % (a, b, c, d) for (a, b, c), d in naislist)))

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  • Approach for altering Primary Key from GUID to BigInt in SQL Server related tables

    - by Tom
    I have two tables with 10-20 million rows that have GUID primary keys and at leat 12 tables related via foreign key. The base tables have 10-20 indexes each. We are moving from GUID to BigInt primary keys. I'm wondering if anyone has any suggestions on an approach. Right now this is the approach I'm pondering: Drop all indexes and fkeys on all the tables involved. Add 'NewPrimaryKey' column to each table Make the key identity on the two base tables Script the data change "update table x, set NewPrimaryKey = y where OldPrimaryKey = z Rename the original primarykey to 'oldprimarykey' Rename the 'NewPrimaryKey' column 'PrimaryKey' Script back all the indexes and fkeys Does this seem like a good approach? Does anyone know of a tool or script that would help with this? TD: Edited per additional information. See this blog post that addresses an approach when the GUID is the Primary: http://www.sqlmag.com/blogs/sql-server-questions-answered/sql-server-questions-answered/tabid/1977/entryid/12749/Default.aspx

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  • Filtering forms in MS Access

    - by terence6
    I have a simple form showing products from my database. Each product has a foreign key to manufacturer_id . I would like to filter my form by manufacturer_id instead of default product_id. How I can do that ? I know I must create a macro. Also I've already created a query, that takes manufacturer's name as argument and returns manufacturer_id. So basically it should work in this way, that when I press 'Filter' button on my form, it runs macro that opens my query asking for manufacturer's name. And when the name is returned the whole form is filtered (so somewhere there should be comparison between manufacturer_id in product and that returned from query, but I can't manage to do that). I'm using access 2007. Model:

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  • Exploring search options for PHP

    - by Joshua
    I have innoDB table using numerous foreign keys, but we just want to look up some basic info out of it. I've done some research but still lost. 1) How can I tell if my host has Sphinx installed already? I don't see it as an option for table storage method (i.e. innodb, myisam). 2) Zend_Search_Lucene, responsive enough for AJAX functionality of millions of records? 3) Mirror my innoDB with a myisam? Make every innodb transaction end with a write to the myisam, then use 1:1 lookups? How would I do this automagically? This should make MyISAM ACID-compliant and free(er) from corruption no? 4) PostgreSQL fulltext queries don't even look like SQL to me wtf, I don't have time to learn a new SQL syntax I need noob options 5) ???????????????????? This is high volume site on a decently-equipped VPS Thanks very much for any ideas.

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  • SQL Query in NHibernate diction

    - by Jan-Frederik Carl
    I have a SQL Query which works in SQL Management Studio: Select Id From table t Where t.Date= (Select Max(Date) From ( Select * From table where ReferenceId = xy) u) Reason is, from all entries with a certain foreign key, I want to receive the one with the highest date. I tried to reform this Query for use in NHibernate, and I got IQuery query = session.CreateQuery(String.Format( @"Select t.Id From table t Where t.Date = (Select Max(Date) From (Select * From table t where t.ReferenceItem.Id = " + item.ReferenceItem.Id + ")u)")); I get the error message: "In expected" How do I have to form the NHibernate query? What does the "In" mean?

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  • InnoDB not supported by webhost. What now?

    - by Peter Perhác
    I was developing a small WAMP web application on my laptop, where I have an instance of mySQL running and I chose InnoDB for my DB engine. After several weeks' development I wanted to make it available to the public and found out the database server provided by my web host does not support InnoDB, only MyISAM. The create-and-populate script generated from the innoDB schema on my laptop, when executed against the live database, can manage to create individual TABLES but then runs into problems creating the VIEWs. Are views not supported in MyISAM? I know FOREIGN KEYs are not. That's very much why I made the choice of InnoDB... What are my chances of making my innoDB schema design work with myISAM? Is there any straightforward way of converting the whole schema from one storage engine to the other? Should I look for another web host that does provide a mysql db that supports innoDB?

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  • Django - Passing arguments to models through ForeignKey attributes

    - by marshall
    I've got a class like this: class Image (models.Model): ... sizes = ((90,90), (300,250)) def resize_image(self): for size in sizes: ... and another class like this: class SomeClassWithAnImage (models.Model): ... an_image = models.ForeignKey(Image) what i'd like to do with that class is this: class SomeClassWithAnImage (models.Model): ... an_image = models.ForeignKey(Image, sizes=((90,90), (150, 120))) where i'm can specify the sizes that i want the Image class to use to resize itself as a argument rather than being hard coded on the class. I realise I could pass these in when calling resize_image if that was called directly but the idea is that the resize_image method is called automatically when the object is persisted to the db. if I try to pass arguments through the foreign key declaration like this i get an error straight away. is there an easy / better way to do this before I begin hacking down into django?

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  • MySQL query for initial filling of order column

    - by Sejanus
    Sorry for vague question title. I've got a table containing huge list of, say, products, belonging to different categories. There's a foreign key column indicating which category that particular product belongs to. I.e. in "bananas" row category might be 3 which indicates "fruits". Now I added additional column "order" which is for display order within that particular category. I need to do initial ordering. Since the list is big, I dont wanna change every row by hand. Is it possible to do with one or two queries? I dont care what initial order is as long as it starts with 1 and goes up. I cant do something like SET order = id because id counts from 1 up regardless of product category and order must start anew from 1 up for every different category.

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  • Check if row already exists, if so tell the referenced table the id

    - by flhe
    Let's assume I have a table magazine: CREATE TABLE magazine ( magazine_id integer NOT NULL DEFAULT nextval(('public.magazine_magazine_id_seq'::text)::regclass), longname character varying(1000), shortname character varying(200), issn character varying(9), CONSTRAINT pk_magazine PRIMARY KEY (magazine_id) ); And another table issue: CREATE TABLE issue ( issue_id integer NOT NULL DEFAULT nextval(('public.issue_issue_id_seq'::text)::regclass), number integer, year integer, volume integer, fk_magazine_id integer, CONSTRAINT pk_issue PRIMARY KEY (issue_id), CONSTRAINT fk_magazine_id FOREIGN KEY (fk_magazine_id) REFERENCES magazine (magazine_id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE NO ACTION ); Current INSERTS: INSERT INTO magazine (longname,shotname,issn) VALUES ('a long name','ee','1111-2222'); INSERT INTO issue (fk_magazine_id,number,year,volume) VALUES (currval('magazine_magazine_id_seq'),'8','1982','6'); Now a row should only be inserted into 'magazine', if it does not already exist. However if it exists, the table 'issue' needs to get the 'magazine_id' of the row that already exists in order to establish the reference. How can i do this? Thx in advance!

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  • How to configure Hibernate database reverse engineering tool to map database table relation as a ent

    - by Piotr Kochanski
    Is it possible to configure Hibernate reverse engineering and code generation tool in such a way that one-to-many relation between tables is mapped to entities inheritance instead of enrites relation? I have Person table and Employee table, which are related with the foreign key (Person contains basic information, Employee the rest). In my Java code I would like this relation mapped to inheritance Employee extends Person. This can be done by hand, but maybe I missed some custom configuration parameter that I can use. I couldn't find any official documentation - docs link on RedHat Hibernate page (http://www.hibernate.org/5.html#A10) is broken...

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  • Entity Framework: Setting EntityReference EntityKey causes exception on save

    - by NYSystemsAnalyst
    I have a table with a ModifiedUserID field that is a foreign key to a User table. In entity framework, I'm loading the first table, but not the users table. I have the user ID of the current user, and would like to set the ModifiedUserID to that value for all entities that have been modified prior to saving. Before calling SaveChanges(), I use the ObjectStateManager to get all modified entities. Since I do not have the user object, but I do have the user ID, I set the EntityReference.EntityKey property as follows: entity.UserReference.EntityKey = New EntityKey("MyContainer.User", "UserID", DatabaseUserID) This works fine, but when I execute SaveChanges(), I receive the following error: A relationship is being added or deleted from an AssociationSet 'FK_Table1_User'. With cardinality constraints, a corresponding 'Table1' must also be added or deleted. Now, I see that setting the EntityReference.EntityKey creates a new AssociationSet entry, but how to I prevent this error?

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  • Injecting relationships in DBIx::Class

    - by Carl
    I have a handful of DBIx::Class::Core objects that model various database tables. For some of those models (those that have a 'queue' column), I have another class inject subs (basically, to 'move' the model object along it's queue states). I'd like to also have that class inject has_many relationships ala class($name)->has_many('queue_history','MySchema::Result::QueueHistory', { 'foreign.record_id'=>'self.id' }, { where => { type => $name }} ); but I can't seem to get the relationships to register properly (keep getting "No Such Relationship" errors - however, when calling the relationship method on the sources provides back the relationship). Any clues as to what's wrong?

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  • Java JPA @OneToMany neededs to reciprocate @ManyToOne?

    - by bguiz
    Create Table A ( ID varchar(8), Primary Key(ID) ); Create Table B ( ID varchar(8), A_ID varchar(8), Primary Key(ID), Foreign Key(A_ID) References A(ID) ); Given that I have created two tables using the SQL statements above, and I want to create Entity classes for them, for the class B, I have these member attributes: @Id @Column(name = "ID", nullable = false, length = 8) private String id; @JoinColumn(name = "A_ID", referencedColumnName = "ID", nullable = false) @ManyToOne(optional = false) private A AId; In class A, do I need to reciprocate the many-to-one relationship? @Id @Column(name = "ID", nullable = false, length = 8) private String id; @OneToMany(cascade = CascadeType.ALL, mappedBy = "AId") private List<B> BList; //<-- Is this attribute necessary? Is it a necessary or a good idea to have a reciprocal @OneToMany for the @ManyToOne? If I make the design decision to leave out the @OneToMany annotated attribute now, will come back to bite me further down.

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  • how to model a many to many relationship

    - by Maulin
    Here is the scenario, Articles have many Comments Users can write many Comments for many Articles The comments table contains both user_id article_id as foreign keys My models are set up like so class User < ActiveRecord::Base has_many :comments has_many :articles, :through => :comments class Article < ActiveRecord::Base has_many :comments has_many :users, :through => :comments class Comment < ActiveRecord::Base belongs_to :users belongs_to :articles My routes.rb has the following code map.resources :articles, :has_many => :comments map.resources :users, :has_many => :comments which produces the following routes new_article_comment edit_article_comment new_user_comment edit_user_comment etc... This is not what I want (atleast not what I think I want), since comments must always be related to users and article, how can I get a route like so new_user_article_comment edit_user_article_comment Then I could just do new_user_article_comment_path([@user, @article]) to create a new comment

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