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  • Django: Set foreign key using integer?

    - by User
    Is there a way to set foreign key relationship using the integer id of a model? This would be for optimization purposes. For example, suppose I have an Employee model: class Employee(models.Model): first_name = models.CharField(max_length=100) last_name = models.CharField(max_length=100) type = models.ForeignKey('EmployeeType') and EmployeeType(models.Model): type = models.CharField(max_length=100) I want the flexibility of having unlimited employee types, but in the deployed application there will likely be only a single type so I'm wondering if there is a way to hardcode the id and set the relationship this way. This way I can avoid a db call to get the EmployeeType object first.

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  • Rails: Design Pattern to Store Order of Relations

    - by ChrisInCambo
    Hi, I have four models: Customer, QueueRed, QueueBlue, QueueGreen. The Queue models have a one to many relationship with customers A customer must always be in a queue A customer can only be in one queue at a time A customer can change queues We must be able to find out the customers current position in their respective queue In an object model the queues would just have an array property containing customers, but ActiveRecord doesn't have arrays. In a DB I would probably create some extra tables just to handle the order of the stories in the queue. My question is what it the best way to model the relationship in ActiveRecord? Obviously there are many ways this could be done, but what is the best or the most in line with how ActiveRecord should be used? Cheers, Chris

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  • Saving a Django form with a Many2Many field with through table

    - by PhilGo20
    So I have this model with multiple Many2Many relationship. 2 of those (EventCategorizing and EventLocation are through tables/intermediary models) class Event(models.Model): """ Event information for Way-finding and Navigator application""" categories = models.ManyToManyField('EventCategorizing', null=True, blank=True, help_text="categories associated with the location") #categories associated with the location images = models.ManyToManyField(KMSImageP, null=True, blank=True) #images related to the event creator = models.ForeignKey(User, verbose_name=_('creator'), related_name="%(class)s_created") locations = models.ManyToManyField('EventLocation', null=True, blank=True) In my view, I first need to save the creator as the request user, so I use the commit=False parameter to get the form values. if event_form.is_valid(): event = event_form.save(commit=False) #we save the request user as the creator event.creator = request.user event.save() event = event_form.save_m2m() event.save() I get the following error: *** TypeError: 'EventCategorizing' instance expected I can manually add the M2M relationship to my "event" instance, but I am sure there is a simpler way. Am I missing on something ?

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  • Foreign key on table A --> B, AND foreign key on table B --> A. How is this done?

    - by unclaimedbaggage
    Hi, I have two tables - 'business' and 'business_contacts'. The business_contact table has a many-to-one relationship with the business table. Furthermore, each business has a 'primary contact' field - which I'd assume is a one-to-many relationship with the business_contacts table. The problem, of course, is that this creates a catch-22 for data insertion. Since neither field can be null, I can't insert a business_contact until I have a corresponding business, but I can't insert a business until I have a corresponding business_contact. If anyone could help me get my head around how mutual one-to-many relationships are supposed to be dealt with I'd be most appreciative. (Project being done in MySQL if it makes any difference)

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  • Eager loading in EF1.0

    - by Dave Swersky
    I have a many-to-many relationship: Application - Applications_Servers - Server This is set up in my Entity Data Model and all is well. My problem is that I'd like to eager-load the whole graph of Applications so that I have an IEnumerable<Applications>, each Application member populated with the Servers collection associated by the many-to-many relationship. Normally this wouldn't be a problem, but according to my research there must be a navigation property between Application and Server. This is not the case for me because my Applications_Servers join table has more in it than just the two keys. Therefore, there is no navigation property directly between Application and Server, and this doesn't work: var apps = (from a in context.Application.Include("Server") select a).ToList(); I get an error saying there is no navigation property on Application called "Server", and that's correct, there is none. How do I write the query to eager-load my Applications with their Servers in this case?

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  • Two Different Types of Associatons on the Same Two Tables in Rails

    - by tmo256
    I have two models, users and themes, that I'm currently joining in a HABTM association in a themes_users table. Basically, after a user creates a new theme, it becomes available to other users to select for their own use. However, only the original creator of the theme should have the ability to edit it. So, I need to have some other kind of association to handle that relationship, something like an created_by_id field in the theme. In this way, the user model acts as two different roles: they can be an implementer of a theme AND/OR the owner of the theme. The implementer relationship is handled by the themes_users join table; the question is: What is the right way to handle this secondary association? Do I need to make users polymorphic and then make the created_by_id reference an "owner"? Or is there something easier? Thanks so much for your help!

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  • Microsoft Visual Studio License

    - by Germstorm
    I developed a small winforms application for myself in Microsoft Visual Studio 2008 Professional Edition at my workplace, the Visual Studio is licensed to the firm I work at. If I want to sell that application, what are my license options? EDIT: The issue here is not my relationship with my employer (the code was written after hours, we have an understanding) but my relationship with Microsoft. Ex. if I continue developing in Visual Studio Express can I keep my old code? Is there a way to verify if some assemblies were written using a Visual Studio Professional?

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  • JPA 2.0 Eclipse Link ... Composite primary keys

    - by Parhs
    I have two entities(actually more but it doenst matter) Exam and Exam_Normals Its a oneToMany relationship... The problem is that i need a primary key for Exams_Normals PK (Exam_ID Item) Item should be 1 2 3 4 5 etc.... But cant achieve it getting errors An alternative would be to: I cound use an IDENTITY and a ManyToOne relationship at Exam_Normals but that should be like PK(Exam_Normals_ID) and a reference to Exam and an extra collumn Item to keep an order.. SO 3 collumns But to avoid the alternative tried I tried with @IdClass and got errors Tried @EmbeddedID everything nothing works Any idea??

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  • Hibernate Many-To-One Foreign Key Default 0

    - by user573648
    I have a table where the the parent object has an optional many-to-one relationship. The problem is that the table is setup to default the fkey column to 0. When selecting, using fetch="join", etc-- the default of 0 on the fkey is being used to try over and over to select from another table for the ID 0. Of course this doesn't exist, but how can I tell Hibernate to treat a value of 0 to be the same as NULL-- to not cycle through 20+ times in fetching a relationship which doesn't exist? <many-to-one name="device" lazy="false" class="Device" not-null="true" access="field" cascade="none" not-found="ignore"> <column name="DEVICEID" default="0" not-null="false"/>

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  • Fluent mapping help

    - by Matt Thrower
    Hi, This is probably a very simple question but I'm new to nHibernate and I'm having trouble working this out. I have a Page object, which can have many Region objects. I also have a Workflow object. Page and Region objects both have a relationship to Workflow and it's this double association that I'm having trouble with. The PageMap has HasMany(Function(x) x.Regions).Cascade.All() And the RegionMap has: References(Function(x) x.Page) And this all seems to work. But how do I define the relationship between Workflow and these two objects?

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  • Chaining Many-To-Many Dimensional Relationships in SSAS

    - by Ray Saltrelli
    I'm developing a cube in SSAS and attempting to model the following relationships: Many Facts to 1 Customer Many Customers to Many Sales Reps Many Sales Reps (Subordinates) to Sales Reps (Managers) Each M2M relationship is facilitated by a bridge table which also acts as a fact table in the cube I have most of this working. I can slice Facts by Customer and by Sales Rep (Subordinate), but when I add Sales Rep (Manager) to the query it appears to return every subordinate/manager combination regardless of whether or not that relationship exists in the bridge table. Any ideas as to what I might be doing wrong?

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  • Assign TableView column binding to a specific core-data object in to-many related entity based on se

    - by snown27
    How would I assign a column of a TableView to be a specific entry in a Core Data entity that is linked to the NSArrayController via a to-many relationship? For example Entity: MovieEntity Attributes: title(NSString), releaseDate(NSDate) Relationship: posters<-->> PosterEntity Entity:PosterEntity Attributes: imageLocation(NSURL), default(BOOL) Relationships: movie<<--> MovieEntity So I have a three column table that I want to display the Poster, Title, and Release Date attributes in, but as one movie could potentially have several different style's of posters how do I get the poster column to only show the one that's marked default? Since the rest of the table is defined in Interface Builder I would prefer to keep it that way for the sake of keeping the code as clean as possible, but if this can only be done programmatically then I'm all ears. I just wanted to give preference in case there's more than one way to skin a cat, so to speak.

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  • SQL Analysis Services - Dimension attributes with a "many" cardinality

    - by MonkeyBrother
    I am creating a cube with the following tables: Customer CustomerID, Name Customer Rep CustomerID, RepID Rep RepID, Name The important thing here is that there is a many to many relationship between Reps and Customers. I want to be able to ask the question "How much sales for customers working with rep 'A'?" In the data source view i set up the relationships between both customerid columns and both repid columns. I set up the rep attribute in the dimension builder and when I try to build the cube I get this error: Errors in the high-level relationship engine. the 'Rep' table that is required for a join cannot be reached based on the relationships in the data source view.

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  • Best way to order by columns in relationships?

    - by Timmy
    im using sqlalchemy, and i have a few polymorphic tables, and i want to sort by a column in one of the relationship. i have tables a,b,c,d, with relationship a to b, b to c, c to d. a to b is one-to-many b to c and c to d are one-to-one, but polymorphic. given an item in table a, i will have a list of items b, c, d (all one to one). how do i use sqlalchemy to sort them by a column in table d?

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  • Using Java, can I have one JVM spawn another, and then have the original one exit?

    - by CarlG
    I have a need to have a running JVM start another JVM and then exit. I'm currently trying to do this via Runtime.getRuntime().exec(). The other JVM starts, but my original JVM won't exit until the "child" JVM process stops. It appears that using Runtime.getRuntime().exec() creates a parent-child relationship between the processes. Is there some way to de-couple the spawned process so that the parent can die, or some other mechanism to spawn a process without any relationship to the creating process? Note that this seems exactly like this question: http://stackoverflow.com/questions/2566502/using-java-to-spawn-a-process-and-keep-it-running-after-parent-quits but the accepted answer there doesn't actually work, at least not on my system (Windows 7, Java 5 and 6). It seems that maybe this is a platform-dependent behavior. I'm looking for a platform independent way to reliably invoke the other process and let my original process die.

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  • Fluent Nhibernate mapping related items

    - by Josh
    I am trying to relate 2 items. I have a table that is simply an Id field, and then 2 columns for the Item Id's to relate. I want it to be a 2 way relationship - that is, if the items appear twice in the table, I only want one relationship connection back. So, here's my item: public class Item { public virtual Guid ItemId {get; set;} public virtual string Name {get; set;} public virtual IList<Item> RelatedItems {get; set;} } The table for relating the items looks like this: CREATE TABLE RelatedItems ( RelatedItemId uniqueidentifier NOT NULL, ItemId uniqueidentifier NOT NULL, RelatedId uniqueidentifier NOT NULL, CONSTRAINT PK_RelatedItems PRIMARY KEY CLUSTERED (RelatedItemId) ) What is the best way to map this connection?

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  • mysql codeigniter active record m:m deletion

    - by sea_1987
    Hi There, I have a table 2 tables that have a m:m relationship, what I can wanting is that when I delete a row from one of the tables I want the row in the joining table to be deleted as well, my sql is as follow, Table 1 CREATE TABLE IF NOT EXISTS `job_feed` ( `id` int(11) NOT NULL AUTO_INCREMENT, `body` text NOT NULL, `date_posted` int(10) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; Table 2 CREATE TABLE IF NOT EXISTS `job_feed_has_employer_details` ( `job_feed_id` int(11) NOT NULL, `employer_details_id` int(11) NOT NULL, PRIMARY KEY (`job_feed_id`,`employer_details_id`), KEY `fk_job_feed_has_employer_details_job_feed1` (`job_feed_id`), KEY `fk_job_feed_has_employer_details_employer_details1` (`employer_details_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; So what I am wanting to do is, if the a row is deleted from table1 and has an id of 1 I want the row in table to that also has that idea as part of the relationship also. I want to do this in keeping with codeigniters active record class I currently have this, public function deleteJobFeed($feed_id) { $this->db->where('id', $feed_id) ->delete('job_feed'); return $feed_id; }

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  • How could I compare these database values in PHP?

    - by Dan
    So a user selects from a drop down list a value. I take this value, put it into a variable, then select from the database the ID value of that table A holding the selected value also. So now I'm trying to use that ID value to get to a many-to-many relationship table that has the selected value from table A to a different table B. The many-to-many relationship table has both IDs. How can I compare this using PHP? So it would be like: $A = $_POST['a']; $sql = "SELECT a, aID from TABLEA WHERE a = $A"; What do I do then to compare the aID with the many-to-many relationships table, then get the other ID in that table and then take that ID to get values from table B?

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  • Interviewing a DBA

    - by kev
    Our Company is in the Process of recuiting a DBA. I have built a group test of questions from basic questions such as Pk and Fk constraints, simple querries(fizzbuzz style) to more advanced things such as indexes, Collation, isolation levels and how to trace deadlocks. However, that is the limit of my knowledge. So my question to all the DBA's is what is the base level knowledge that all DBA's should have? We are really looking for someone that will be able to manage our replication, analyzing some of our slower running queries(that the devs can go to for help) and someone that can trace some of the deadlock issues that we are having. Any help would be most appreciated!

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  • Interviewing a DBA

    - by kev
    Our Company is in the Process of recuiting a DBA. I have built a group test of questions from basic questions such as Pk and Fk constraints, simple querries(fizzbuzz style) to more advanced things such as indexes, Collation, isolation levels and how to trace deadlocks. However, that is the limit of my knowledge. So my question to all the DBA's is what is the base level knowledge that all DBA's should have? We are really looking for someone that will be able to manage our replication, analyzing some of our slower running queries(that the devs can go to for help) and someone that can trace some of the deadlock issues that we are having. Any help would be most appreciated!

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  • Having a generic data type for a database table column, is it "good" practice?

    - by Yanick Rochon
    I'm working on a PHP project where some object (class member) may contain different data type. For example : class Property { private $_id; // (PK) private $_ref_id; // the object reference id (FK) private $_name; // the name of the property private $_type; // 'string', 'int', 'float(n,m)', 'datetime', etc. private $_data; // ... // ..snip.. public getters/setters } Now, I need to perform some persistence on these objects. Some properties may be a text data type, but nothing bigger than what a varchar may hold. Also, later on, I need to be able to perform searches and sorting. Is it a good practice to use a single database table for this (ie. is there a non negligible performance impact)? If it's "acceptable", then what could be the data type for the data column?

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  • Optimal Database design regarding functionality of letting user share posts by other users

    - by codecool
    I want to implement functionality which let user share posts by other users similar to what Facebook and Google+ share button and twitter retweet. There are 2 choices: 1) I create duplicate copy of the post and have a column which keeps track of the original post id and makes clear this is a shared post. 2) I have a separate table shared post where I save the post id which is a foreign key to post id in post table. Talking in terms of programming basically I keep pointer to the original post in a separate table and when need to get post posted by user and also shared ones I do a left join on post and shared post table Post(post_id(PK), post_content, posted_by) SharedPost(post_id(FK to Post.post_id), sharing_user, sharedfrom(in case someone shares from non owners profile)) I am in favour of second choice but wanted to know the advice of experts out there? One thing more posts on my webapp will be more on the lines of facebook size not tweet size.

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  • Q: Is it me or is ADO.NET **BACKWARDS**? (20 replies)

    To simplify the question, I create 2 tables in SQL. Table 1 has columns: ColumnA (PK), ColumnB and Type. Table 2 has columns: A (PK) and Description Now, I want to set things up so that Table 1.Type is of type Table 2.A. 1) I guess in SQL lingo, what I'm trying to say is that Table 1.Type is a FK to Table 2.A. Is that correct terminology? Is that backwards? It appears to me to be correct. 2) So I ...

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  • Q: Is it me or is ADO.NET **BACKWARDS**? (20 replies)

    To simplify the question, I create 2 tables in SQL. Table 1 has columns: ColumnA (PK), ColumnB and Type. Table 2 has columns: A (PK) and Description Now, I want to set things up so that Table 1.Type is of type Table 2.A. 1) I guess in SQL lingo, what I'm trying to say is that Table 1.Type is a FK to Table 2.A. Is that correct terminology? Is that backwards? It appears to me to be correct. 2) So I ...

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