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  • Creating Two Cascading Foreign Keys Against Same Target Table/Col

    - by alram
    I have the following tables: user (userid int [pk], name varchar(50)) action (actionid int [pk], description nvarchar(50)) being referenced by another table that captures the relationship: <user1> <action>'s <user2>. I did this with the following table: userAction (userActionId int [pk], actionid int [fk: action.actionid], **userId1 int [fk ref's user.userid; on del/update cascade], userId2 int [fk ref's user.userid; on del/update cascade]**). However, when I try to save the userAction table i get an error because I have two cascading fk's against user.userid. Is there any way to remedy this or must I use a trigger?

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  • Trying to verify understanding of Foreign Keys MSSQL

    - by msarchet
    So I'm working on just a learning project to expose myself to doing some things I do not get to do at work. I'm just making a simple bug and case tracking app (I know there are a million this is just to work with some tools I don't get to). So I was designing my database and realized I've never actually used Foreign Keys before in any of my projects, I've used them before but never actually setting up a column as a FK. So I've designed my database as follows, which I think is close to correct (at least for the initial layout). However When I try to add the FK's to the linking Tables I get an error saying, "The tables present in the relationship must have the same number of columns". I'm doing this by in SQLSMS by going to the Keys 'folder' and adding a FK. Is there something that I am doing wrong here, I don't understand why the tables would have to have the same number of columns for me to add a FK relationship between the tables?

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  • SQL Syntax for Complex Scenario (Deals)

    - by Yisman
    hello everyone i have a complex query to be written but cannot figure it out here are my tables Sales --one row for each sale made in the system SaleProducts --one row for each line in the invoice (similar to OrderDetails in NW) Deals --a list of possible deals/offers that a sale may be entitled to DealProducts --a list of quantities of products that must be purchased in order to get a deal now im trying to make a query which will tell me for each sale which deals he may get the relevant fields are: Sales: SaleID (PK) SaleProducts: SaleID (FK), ProductID (FK) Deals: DealID (PK) DealProducts: DealID(FK), ProductID(FK), Mandatories (int) for required qty i believe that i should be able to use some sort of cross join or outer join, but it aint working here is one sample (of about 30 things i tried) SELECT DealProducts.DealID, DealProducts.ProductID, DealProducts.Mandatories, viwSaleProductCount.SaleID, viwSaleProductCount.ProductCount FROM DealProducts LEFT OUTER JOIN viwSaleProductCount ON DealProducts.ProductID = viwSaleProductCount.ProductID GROUP BY DealProducts.DealID, DealProducts.ProductID, DealProducts.Mandatories, viwSaleProductCount.SaleID, viwSaleProductCount.ProductCount the problem is that it doesnt show any product deals that r not fullfiled (probably because of the productid join). i need that also sales that dont have the requiremnets show up, then i can filter out any saleid that exists in this query "where AmountBought thank you for your help

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  • Symfony 1.4: Deleting a sfGuardUser

    - by Tom
    Hi, I'm having some trouble with the following... I have a sfGuardUser table set up normally, and it has a one-to-one relationship with a Profile table, which contains some additional user info. When a user wants to delete themselves from the site, I'd like to retain their info in the Profile table for various purposes BUT delete the sfGuardUser in order to keep that table cleaner/shorter (not just set it to inactive). I was under the impression that I could set the FK in the Profile table to NULL and then delete the sfGuardUser, but it seems the FK-constraint fails. Indeed, it seems I can't delete either and the queries fail: If I try to delete the sfGuardUser, the Profile table will have an invalid FK If I try to delete a Profile, the sfGuardUser will have an invalid FK Other than leaving outdated sfGuardUsers and Profiles in these tables, or having to use a cascaded delete to get rid of both, can anyone tell me if there's any other way around this? Thank you.

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  • best database design for city zip & state tables

    - by ryan a
    My application will need to reference addresses. Street info will be stored with my main objects but the rest needs to be stored seperately to reduce redundancy. How should I store/retrieve ZIPs, cities and states? Here are some of my ideas. single table solution (cant do relationships) [locations] locationID locationParent (FK for locationID - 0 for state entries) locationName (city, state) locationZIP two tables (with relationships, FK constraints, ref integrity) [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName zipCode three tables [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName [zip] zipID cityID (FK for city.cityID) zipName Then I read into ZIP codes amd how they are assigned. They aren't specifically related to cities. Some cities have more than one ZIP (ok will still work) but some ZIPs are in more than one city (oh snap) and some other ZIPs (very few) are in more than one state! Also some ZIPs are not even in the same state as the address they belong to at all. Seems ZIPs are made for carrier route identification and some remote places are best served by post offices in neighboring cities or states. Does anybody know of a good (not perfect) solution that takes this into consideration to minimize discrepencies as the database grows?

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  • basic database design table on rails

    - by runcode
    I am confuse on a concept. I am doing this on rails. Is that Entity set equal to a table in the database? Is that Relationship set equal to a table in the database? Let say we have Entity set "USER" and Entity set "POST" and Entity set "COMMENT" User- can post many posts and comments as they want Post- belong to users Comments-belong to posts ,users, so comment is weak entity. SCHEMA ====== USER -id -name POST -id -user_id(FK) -comment_id (FK) COMMENT -id -user_id (FK) -post_id (FK) so USER,POST,COMMENT are tables I think. And what else is a table? And do I need a table for the relationship??

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  • Creating new Entities from Stored Procedure

    - by SK
    I have a stored procedure that retrieves existing rows from a table and also creates includes new rows that match the table definition and mapped entity (.net 3.5 entity framework). These new rows are not written to the database in the stored procedure. The stored procedure executes, but the new rows that were created will not load the navigation properties sucessfully i.e. the rows that do not actually exist in the database. e.g. database rows: key, data, FK 1, xxx, a 2, xxx, b returned rows from stored procedure: key, data, FK 1, xxx, a 2, xxx, b 3, yyy, a 4, yyy, b The entity will load FK entities a and b for rows 1 and 2, but for rows 3 and 4 the FK entity is null. Do I somehow need to add the new rows to the data context? or turn off tracking?

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  • Unnecessary Redundancy with Tables.

    - by Stacey
    My items are listed as follows; This is just a summary of course. But I'm using a method shown for the "Detail" table to represent a type of 'inheritence', so to speak - since "Item" and "Downloadable" are going to be identical except that each will have a few additional fields relevant only to them. My question is in this design pattern. This sort of thing appears many, many times in our projects - is there a more intelligent way to handle it? I basically need to normalize the tables as much as possible. I'm extremely new to databases and so this is all very confusing to me. There are 5 items. Awards, Items, Purchases, Tokens, and Downloads. They are all very, very similar, except each has a few pieces of data relevant only to itself. I've tried to use a declaration field (like an enumerator 'Type' field) in conjunction with nullable columns, but I was told that is a bad approach. What I have done is take everything similar and place it in a single table, and then each type has its own table that references a column in the 'base' table. The problem occurs with relationships, or junctions. Linking all of these back to a customer. Each type takes around 2 additional tables to properly junction all of the data together- and as such, my database is growing very, very large. Is there a smarter practice for this kind of behavior? Item ID | GUID Name | varchar(64) Product ID | GUID Name | varchar(64) Store | GUID [ FK ] Details | GUID [FK] Downloadable ID | GUID Name | varchar(64) Url | nvarchar(2048) Details | GUID [FK] Details ID | GUID Price | decimal Description | text Peripherals [ JUNCTION ] ID | GUID Detail | GUID [FK] Store ID | GUID Addresses | GUID Addresses ID | GUID Name | nvarchar(64) State | int [FK] ZipCode | int Address | nvarchar(64) State ID | int Name | varchar(32)

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  • Generate Delete Statement From Foreign Key Relationships in SQL 2008 ?

    - by Element
    Is it possible via script/tool to generate a delete statement based on the tables fk relations. i.e. I have the table: DelMe(ID) and there are 30 tables with fk references to its ID that I need to delete first, is there some tool/script that I can run that will generate the 30 delete statements based on the FK relations for me ? (btw I know about cascade delete on the relations, I can't use it in this existing db) I'm using Microsoft SQL Server 2008

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  • LLBLGen Pro feature highlights: automatic element name construction

    - by FransBouma
    (This post is part of a series of posts about features of the LLBLGen Pro system) One of the things one might take for granted but which has a huge impact on the time spent in an entity modeling environment is the way the system creates names for elements out of the information provided, in short: automatic element name construction. Element names are created in both directions of modeling: database first and model first and the more names the system can create for you without you having to rename them, the better. LLBLGen Pro has a rich, fine grained system for creating element names out of the meta-data available, which I'll describe more in detail below. First the model element related element naming features are highlighted, in the section Automatic model element naming features and after that I'll go more into detail about the relational model element naming features LLBLGen Pro has to offer in the section Automatic relational model element naming features. Automatic model element naming features When working database first, the element names in the model, e.g. entity names, entity field names and so on, are in general determined from the relational model element (e.g. table, table field) they're mapped on, as the model elements are reverse engineered from these relational model elements. It doesn't take rocket science to automatically name an entity Customer if the entity was created after reverse engineering a table named Customer. It gets a little trickier when the entity which was created by reverse engineering a table called TBL_ORDER_LINES has to be named 'OrderLine' automatically. Automatic model element naming also takes into effect with model first development, where some settings are used to provide you with a default name, e.g. in the case of navigator name creation when you create a new relationship. The features below are available to you in the Project Settings. Open Project Settings on a loaded project and navigate to Conventions -> Element Name Construction. Strippers! The above example 'TBL_ORDER_LINES' shows that some parts of the table name might not be needed for name creation, in this case the 'TBL_' prefix. Some 'brilliant' DBAs even add suffixes to table names, fragments you might not want to appear in the entity names. LLBLGen Pro offers you to define both prefix and suffix fragments to strip off of table, view, stored procedure, parameter, table field and view field names. In the example above, the fragment 'TBL_' is a good candidate for such a strip pattern. You can specify more than one pattern for e.g. the table prefix strip pattern, so even a really messy schema can still be used to produce clean names. Underscores Be Gone Another thing you might get rid of are underscores. After all, most naming schemes for entities and their classes use PasCal casing rules and don't allow for underscores to appear. LLBLGen Pro can automatically strip out underscores for you. It's an optional feature, so if you like the underscores, you're not forced to see them go: LLBLGen Pro will leave them alone when ordered to to so. PasCal everywhere... or not, your call LLBLGen Pro can automatically PasCal case names on word breaks. It determines word breaks in a couple of ways: a space marks a word break, an underscore marks a word break and a case difference marks a word break. It will remove spaces in all cases, and based on the underscore removal setting, keep or remove the underscores, and upper-case the first character of a word break fragment, and lower case the rest. Say, we keep the defaults, which is remove underscores and PasCal case always and strip the TBL_ fragment, we get with our example TBL_ORDER_LINES, after stripping TBL_ from the table name two word fragments: ORDER and LINES. The underscores are removed, the first character of each fragment is upper-cased, the rest lower-cased, so this results in OrderLines. Almost there! Pluralization and Singularization In general entity names are singular, like Customer or OrderLine so LLBLGen Pro offers a way to singularize the names. This will convert OrderLines, the result we got after the PasCal casing functionality, into OrderLine, exactly what we're after. Show me the patterns! There are other situations in which you want more flexibility. Say, you have an entity Customer and an entity Order and there's a foreign key constraint defined from the target of Order and the target of Customer. This foreign key constraint results in a 1:n relationship between the entities Customer and Order. A relationship has navigators mapped onto the relationship in both entities the relationship is between. For this particular relationship we'd like to have Customer as navigator in Order and Orders as navigator in Customer, so the relationship becomes Customer.Orders 1:n Order.Customer. To control the naming of these navigators for the various relationship types, LLBLGen Pro defines a set of patterns which allow you, using macros, to define how the auto-created navigator names will look like. For example, if you rather have Customer.OrderCollection, you can do so, by changing the pattern from {$EndEntityName$P} to {$EndEntityName}Collection. The $P directive makes sure the name is pluralized, which is not what you want if you're going for <EntityName>Collection, hence it's removed. When working model first, it's a given you'll create foreign key fields along the way when you define relationships. For example, you've defined two entities: Customer and Order, and they have their fields setup properly. Now you want to define a relationship between them. This will automatically create a foreign key field in the Order entity, which reflects the value of the PK field in Customer. (No worries if you hate the foreign key fields in your classes, on NHibernate and EF these can be hidden in the generated code if you want to). A specific pattern is available for you to direct LLBLGen Pro how to name this foreign key field. For example, if all your entities have Id as PK field, you might want to have a different name than Id as foreign key field. In our Customer - Order example, you might want to have CustomerId instead as foreign key name in Order. The pattern for foreign key fields gives you that freedom. Abbreviations... make sense of OrdNr and friends I already described word breaks in the PasCal casing paragraph, how they're used for the PasCal casing in the constructed name. Word breaks are used for another neat feature LLBLGen Pro has to offer: abbreviation support. Burt, your friendly DBA in the dungeons below the office has a hate-hate relationship with his keyboard: he can't stand it: typing is something he avoids like the plague. This has resulted in tables and fields which have names which are very short, but also very unreadable. Example: our TBL_ORDER_LINES example has a lovely field called ORD_NR. What you would like to see in your fancy new OrderLine entity mapped onto this table is a field called OrderNumber, not a field called OrdNr. What you also like is to not have to rename that field manually. There are better things to do with your time, after all. LLBLGen Pro has you covered. All it takes is to define some abbreviation - full word pairs and during reverse engineering model elements from tables/views, LLBLGen Pro will take care of the rest. For the ORD_NR field, you need two values: ORD as abbreviation and Order as full word, and NR as abbreviation and Number as full word. LLBLGen Pro will now convert every word fragment found with the word breaks which matches an abbreviation to the given full word. They're case sensitive and can be found in the Project Settings: Navigate to Conventions -> Element Name Construction -> Abbreviations. Automatic relational model element naming features Not everyone works database first: it may very well be the case you start from scratch, or have to add additional tables to an existing database. For these situations, it's key you have the flexibility that you can control the created table names and table fields without any work: let the designer create these names based on the entity model you defined and a set of rules. LLBLGen Pro offers several features in this area, which are described in more detail below. These features are found in Project Settings: navigate to Conventions -> Model First Development. Underscores, welcome back! Not every database is case insensitive, and not every organization requires PasCal cased table/field names, some demand all lower or all uppercase names with underscores at word breaks. Say you create an entity model with an entity called OrderLine. You work with Oracle and your organization requires underscores at word breaks: a table created from OrderLine should be called ORDER_LINE. LLBLGen Pro allows you to do that: with a simple checkbox you can order LLBLGen Pro to insert an underscore at each word break for the type of database you're working with: case sensitive or case insensitive. Checking the checkbox Insert underscore at word break case insensitive dbs will let LLBLGen Pro create a table from the entity called Order_Line. Half-way there, as there are still lower case characters there and you need all caps. No worries, see below Casing directives so everyone can sleep well at night For case sensitive databases and case insensitive databases there is one setting for each of them which controls the casing of the name created from a model element (e.g. a table created from an entity definition using the auto-mapping feature). The settings can have the following values: AsProjectElement, AllUpperCase or AllLowerCase. AsProjectElement is the default, and it keeps the casing as-is. In our example, we need to get all upper case characters, so we select AllUpperCase for the setting for case sensitive databases. This will produce the name ORDER_LINE. Sequence naming after a pattern Some databases support sequences, and using model-first development it's key to have sequences, when needed, to be created automatically and if possible using a name which shows where they're used. Say you have an entity Order and you want to have the PK values be created by the database using a sequence. The database you're using supports sequences (e.g. Oracle) and as you want all numeric PK fields to be sequenced, you have enabled this by the setting Auto assign sequences to integer pks. When you're using LLBLGen Pro's auto-map feature, to create new tables and constraints from the model, it will create a new table, ORDER, based on your settings I previously discussed above, with a PK field ID and it also creates a sequence, SEQ_ORDER, which is auto-assigns to the ID field mapping. The name of the sequence is created by using a pattern, defined in the Model First Development setting Sequence pattern, which uses plain text and macros like with the other patterns previously discussed. Grouping and schemas When you start from scratch, and you're working model first, the tables created by LLBLGen Pro will be in a catalog and / or schema created by LLBLGen Pro as well. If you use LLBLGen Pro's grouping feature, which allows you to group entities and other model elements into groups in the project (described in a future blog post), you might want to have that group name reflected in the schema name the targets of the model elements are in. Say you have a model with a group CRM and a group HRM, both with entities unique for these groups, e.g. Employee in HRM, Customer in CRM. When auto-mapping this model to create tables, you might want to have the table created for Employee in the HRM schema but the table created for Customer in the CRM schema. LLBLGen Pro will do just that when you check the setting Set schema name after group name to true (default). This gives you total control over where what is placed in the database from your model. But I want plural table names... and TBL_ prefixes! For now we follow best practices which suggest singular table names and no prefixes/suffixes for names. Of course that won't keep everyone happy, so we're looking into making it possible to have that in a future version. Conclusion LLBLGen Pro offers a variety of options to let the modeling system do as much work for you as possible. Hopefully you enjoyed this little highlight post and that it has given you new insights in the smaller features available to you in LLBLGen Pro, ones you might not have thought off in the first place. Enjoy!

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  • Core Data - JSON (TouchJSON) on iPhone

    - by Urizen
    I have the following code which seems to go on indefinitely until the app crashes. It seems to happen with the recursion in the datastructureFromManagedObject method. I suspect that this method: 1) looks at the first managed object and follows any relationship property recursively. 2) examines the object at the other end of the relationship found at point 1 and repeats the process. Is it possible that if managed object A has a to-many relationship with object B and that relationship is two-way (i.e an inverse to-one relationship to A from B - e.g. one department has many employees but each employee has only one department) that the following code gets stuck in infinite recursion as it follows the to-one relationship from object B back to object A and so on. If so, can anyone provide a fix for this so that I can get my whole object graph of managed objects converted to JSON. #import "JSONUtils.h" @implementation JSONUtils - (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject *)managedObject { NSDictionary *attributesByName = [[managedObject entity] attributesByName]; NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName]; //getting the values correspoinding to the attributes collected in attributesByName NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy]; //sets the name for the entity being encoded to JSON [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"]; NSLog(@"+++++++++++++++++> before the for loop"); //looks at each relationship for the given managed object for (NSString *relationshipName in [relationshipsByName allKeys]) { NSLog(@"The relationship name = %@",relationshipName); NSRelationshipDescription *description = [relationshipsByName objectForKey:relationshipName]; if (![description isToMany]) { NSLog(@"The relationship is NOT TO MANY!"); [valuesDictionary setObject:[self dataStructureFromManagedObject:[managedObject valueForKey:relationshipName]] forKey:relationshipName]; continue; } NSSet *relationshipObjects = [managedObject valueForKey:relationshipName]; NSMutableArray *relationshipArray = [[NSMutableArray alloc] init]; for (NSManagedObject *relationshipObject in relationshipObjects) { [relationshipArray addObject:[self dataStructureFromManagedObject:relationshipObject]]; } [valuesDictionary setObject:relationshipArray forKey:relationshipName]; } return [valuesDictionary autorelease]; } - (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects { NSMutableArray *dataArray = [[NSArray alloc] init]; for (NSManagedObject *managedObject in managedObjects) { [dataArray addObject:[self dataStructureFromManagedObject:managedObject]]; } return [dataArray autorelease]; } //method to call for obtaining JSON structure - i.e. public interface to this class - (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects { NSLog(@"-------------> just before running the recursive method"); NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects]; NSLog(@"-------------> just before running the serialiser"); NSString *jsonString = [[CJSONSerializer serializer] serializeArray:objectsArray]; return jsonString; } - (NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary withManagedObjectContext:(NSManagedObjectContext*)moc { NSString *objectName = [structureDictionary objectForKey:@"ManagedObjectName"]; NSManagedObject *managedObject = [NSEntityDescription insertNewObjectForEntityForName:objectName inManagedObjectContext:moc]; [managedObject setValuesForKeysWithDictionary:structureDictionary]; for (NSString *relationshipName in [[[managedObject entity] relationshipsByName] allKeys]) { NSRelationshipDescription *description = [[[managedObject entity]relationshipsByName] objectForKey:relationshipName]; if (![description isToMany]) { NSDictionary *childStructureDictionary = [structureDictionary objectForKey:relationshipName]; NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [managedObject setValue:childObject forKey:relationshipName]; continue; } NSMutableSet *relationshipSet = [managedObject mutableSetValueForKey:relationshipName]; NSArray *relationshipArray = [structureDictionary objectForKey:relationshipName]; for (NSDictionary *childStructureDictionary in relationshipArray) { NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [relationshipSet addObject:childObject]; } } return managedObject; } //method to call for obtaining managed objects from JSON structure - i.e. public interface to this class - (NSArray*)managedObjectsFromJSONStructure:(NSString *)json withManagedObjectContext:(NSManagedObjectContext*)moc { NSError *error = nil; NSArray *structureArray = [[CJSONDeserializer deserializer] deserializeAsArray:[json dataUsingEncoding:NSUTF32BigEndianStringEncoding] error:&error]; NSAssert2(error == nil, @"Failed to deserialize\n%@\n%@", [error localizedDescription], json); NSMutableArray *objectArray = [[NSMutableArray alloc] init]; for (NSDictionary *structureDictionary in structureArray) { [objectArray addObject:[self managedObjectFromStructure:structureDictionary withManagedObjectContext:moc]]; } return [objectArray autorelease]; } @end

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  • What is the relationship between Turing Machine & Modern Computer ? [closed]

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge between a conceptual Turing Machine and a modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • Can Django admin handle a one-to-many relationship via related_name?

    - by Mat
    The Django admin happily supports many-to-one and many-to-many relationships through an HTML <SELECT> form field, allowing selection of one or many options respectively. There's even a nice Javascript filter_horizontal widget to help. I'm trying to do the same from the one-to-many side through related_name. I don't see how it's much different from many-to-many as far as displaying it in the form is concerned, I just need a multi-select SELECT list. But I cannot simply add the related_name value to my ModelAdmin-derived field list. Does Django support one-to-many fields in this way? My Django model something like this (contrived to simplify the example): class Person(models.Model): ... manager = models.ForeignKey('self', related_name='staff', null=True, blank=True, ) From the Person admin page, I can easily get a <SELECT> list showing all possible staff to choose this person's manager from. I also want to display a multiple-selection <SELECT> list of all the manager's staff. I don't want to use inlines, as I don't want to edit the subordinates details; I do want to be able to add/remove people from the list. (I'm trying to use django-ajax-selects to replace the SELECT widget, but that's by-the-by.)

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  • What is the relationship between Turing Machine & Modern Computer ?

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I just cannot build a bridge from a conceptual Turing Machine to a real modern computer. Could someone help me build this bridge? Below is my current understanding. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine.

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  • What is the relationship between WebProxy & IWebProxy with respect to WebClient?

    - by Streamline
    I am creating an app (.NET 2.0) that uses WebClient to connect (downloaddata, etc) to/from a http web service. I am adding a form now to handle allowing proxy information to either be stored or set to use the defaults. I am a little confused about some things. First, some of the methods & properties available in either WebProxy or IWebProxy are not in both. What is the difference here with respect to setting up how WebClient will be have when it is called? Secondly, do I have to tell WebClient to use the proxy information if I set it using either WebProxy or IWebProxy class elsewhere? Or is it automatically inherited? Thirdly, when giving the option for the user to use the default proxy (whatever is set in IE) and using the default credentials (I assume also whatever is set in IE) are these two mutually exclusive? Or you only use default credentials when you have also used default proxy? This gets me to the whole difference between WebProxy and IWebProxy. WebRequest.DefaultProxy is a IWebPRoxy class but UseDefaultCredentials is not a method on the IWebProxy class, rather it is only on WebProxy and in turn, How to set the proxy to the WebRequest.DefautlProxy if they are two different classes? Here is my current method to read the stored form settings by the user - but I am not sure if this is correct, not enough, overkill, or just wrong because of the mix of WebProxy and IWebProxy: private WebProxy _proxyInfo = new WebProxy(); private WebProxy SetProxyInfo() { if (UseProxy) { if (UseIEProxy) { // is doing this enough to set this as default for WebClient? IWebProxy iProxy = WebRequest.DefaultWebProxy; if (UseIEProxyCredentials) { _proxyInfo.UseDefaultCredentials = true; } else { // is doing this enough to set this as default credentials for WebClient? WebRequest.DefaultWebProxy.Credentials = new NetworkCredential(ProxyUsername, ProxyPassword); } } else { // is doing this enough to set this as default for WebClient? WebRequest.DefaultWebProxy = new WebProxy(ProxyAddress, ParseLib.StringToInt(ProxyPort)); if (UseIEProxyCredentials) { _proxyInfo.UseDefaultCredentials = true; } else { WebRequest.DefaultWebProxy.Credentials = new NetworkCredential(ProxyUsername, ProxyPassword); } } } // Do I need to WebClient to absorb this returned proxy info if I didn't set or use defaults? return _proxyInfo; } Is there any reason to not just scrap storing app specific proxy information and only allow the app the ability to use the default proxy information & credentials for the logged in user? Will this ever not be enough if using HTTP? Part 2 Question: How can I test that the WebClient instance is using the proxy information or not?

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  • How can I map one to one relationship in Fluent NHibernate. I have tried everything else

    - by RM
    I have this table structure and would like to map it using Fluent Hibernate (subclass if possible). I cannot change the structure because the database has too many records and might cause major applications rework. It would be easier if the Id from Party table was a foreign key in person and organization table, but in the particular scenario the database has person and organization key as a foreign key in party table. Any help would be great. Party table Id PersonId OrganizationId Person table Id FName LName Organization table Id OrgName OrgDescription

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  • How to make linq master detail query for 0..n relationship?

    - by JK
    Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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  • How to sort objects in a many-to-many relationship in ruby on rails?

    - by Kenji Kina
    I've been trying to deal with this problem for a couple of hours now and haven't been able to come up with a clean solution. It seems I'm not too good with rails... Anyway, I have the following: In code: class Article < ActiveRecord::Base has_many :line_aspects, :dependent => :destroy has_many :aspects, :through => :line_aspects #plus a name field end class LineAspect < ActiveRecord::Base belongs_to :article belongs_to :aspect end class Aspect < ActiveRecord::Base belongs_to :data_type has_many :line_aspects has_many :articles, :through => :line_aspects end Now, what I would like to do, is to sort these in two steps. First list of Articles by their Articles.name, and then inside sort them by Aspect.name (note, not the middleman). For instance, alphabetically (sorry if the notation is not correct): [{ article => 'Apple', line_aspects => [ {:value => 'red'}, #corresponding to the Attribute with :name => 'color' {:value => 'small'} #corresponding to the Attribute with :name => 'shape' ] },{ article => 'Watermelon', line_aspects => [ {:value => 'green'}, #corresponding to the Attribute with :name => 'color' {:value => 'big'} #corresponding to the Attribute with :name => 'shape' ] }] Again, note that these are ordered by the aspect name (color before shape) instead of the specific values of each line (red before green). (NOTE: My intention is to displaye these in a table in the view) I have not found a good way to do this in rails yet (without resorting to N queries). Can anyone tell me a good way to do it?

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  • [Hibernate Mapping] relationship set between table and mapping table to use joins.

    - by Matthew De'Loughry
    Hi guys, I have two table a "Module" table and a "StaffModule" I'm wanting to display a list of modules by which staff are present on the staffmodule mapping table. I've tried from Module join Staffmodule sm with ID = sm.MID with no luck, I get the following error Path Expected for join! however I thought I had the correct join too allow this but obviously not can any one help StaffModule HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Staffmodule" schema="WALK" table="STAFFMODULE"> <composite-id class="Hibernate.StaffmoduleId" name="id"> <key-many-to-one name="mid" class="Hibernate.Module"> <column name="MID"/> </key-many-to-one> <key-property name="staffid" type="int"> <column name="STAFFID"/> </key-property> </composite-id> </class> </hibernate-mapping> and Module.HBM <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Apr 26, 2010 9:50:23 AM by Hibernate Tools 3.2.1.GA --> <hibernate-mapping> <class name="Hibernate.Module" schema="WALK" table="MODULE"> <id name="id" type="int"> <column name="ID"/> <generator class="assigned"/> </id> <property name="modulename" type="string"> <column length="50" name="MODULENAME"/> </property> <property name="teacherid" type="int"> <column name="TEACHERID" not-null="true"/> </property> </class> hope thats enough information! and thanks in advance.

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  • EF4. Add a object with relationship causes full table select

    - by Fujiy
    Ex 1: "autor.ComentariosWorkItens.Add(comentarioWorkItem);" autor.ComentariosWorkItens makes EF4 load all ComentariosWorkItens. Ex 2: comentarioWorkItem.Usuario = autor; Fixup make EF load all ComentariosWorkItens too: private void FixupUsuario(Usuario previousValue) { if (previousValue != null && previousValue.ComentariosWorkItens.Contains(this)) { previousValue.ComentariosWorkItens.Remove(this); } if (Usuario != null) { if (!Usuario.ComentariosWorkItens.Contains(this)) { Usuario.ComentariosWorkItens.Add(this); } } } How can I prevent this?

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  • PHP Doctrine - YAML syntax help. Default value for many to many relationship?

    - by Dan
    Hi, I have the following YAML schema for organising users in Doctrine: Person: tableName: people columns: id: type: integer primary: true autoincrement: true firstname: type: string notnull: true lastname: type: string notnull: true User: inheritance: extends: Person type: column_aggregation keyField: type keyValue: 1 Userdetails: columns: person_id: type: integer primary: true password: type: string notnull: true relations: User: foreignType: one local: person_id onDelete: CASCADE onUpdate: CASCADE Group: tableName: groups columns: id: type: integer primary: true autoincrement: true name: type: string notnull: true UserGroup: columns: group_id: type: integer primary: true person_id: type: integer primary: true relations: User: foreignType: many local: person_id Group: foreignType: many Basically, any people who are users will belong to one or more groups. Is there any way to add new users to a particular group by default? Any advice appreciated. Thanks

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  • Django admin breaking with non-default primary_key for model with a m2m relationship ?

    - by Gj
    I have a simple Post model with a m2m field to a Tag model. The Tag had for some reason to use a non default primary key. Inside the admin page for a Post, the labels for the multiple selection field for Tags appear, but not the input field itself. I also tried using the filter_horizontal for the tags, but still only the labels appear without the actual field. Any ideas why it breaks and/or workarounds? Thanks!

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