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• Mapping one to one foreign key relationships in Entity Framework 4.0?

  - by John K.

  Hello all, I'm sure I'm missing something very simple, but let's say I have two entities, Employee and EmployeeType. Employee type would contain values like 'Full time', 'Contractor', 'Intern', etc. An Employee entity would contain one, and only one EmployeeType value. So I am designing a new .edmx model using the Model-First approach and generating my actual sql server data schema from the model. I want to add an integer type foreign key id into my Employee entity, EmployeeTypeId, which will map to the primary key of the EmployeeType entity. So I've gone ahead and done that in my Employee entity. Where I'm stuck is how, though the Entity Framework designer, to enforce the 1:1 referential constraint on that EmployeeTypeId property? Or does the EF handle that automatically behind the scenes? thanks in advance, John

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• How do I truncate a .NET string?

  - by Steve Guidi

  I apologize for such a question that likely has a trivial solution, but I strangely could not find a concise API for this problem. Essentially, I would like to truncate a string such that it its length is not longer than a given value. I am writing to a database table and want to ensure that the values I write meet the constraint of the column's datatype. For instance, it would be nice if I could write the following: string NormalizeLength(string value, int maxLength) { return value.Substring(0, maxLength); } Unfortunately, this raises an exception because maxLength exceeds the string boundaries. Of course, I could write a function like the following, but I was hoping that something like this already exists. string NormalizeLength(string value, int maxLength) { return value.Length <= maxLength ? value : value.Substring(0, maxLength); } Where is the elusive API that performs this task? Is there one?

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• How to support both DataContractSerializer and XMLSerializer for the same contract on the same host?

  - by Sly

  In our production environment, our WCF services are serialized with the XMLSerializer. To do so our service interfaces have the [XMLSerializerFormat] attribute. Now, we need to change to DataContractSerializer but we must stay compatible with our existing clients. Therefore, we have to expose each service with both serializers. We have one constraint: we don't want to redefine each contract interface twice, we have 50 services contract interfaces and we don't want to have IIncidentServiceXml IIncidentServiceDCS IEmployeeServiceXml IEmployeeServiceDCS IContractServiceXml IContractServiceDCS How can we do that? This is a description of what we have tried so far but I'm willing to try completely different approaches: We tried to create all the endpoints by code in our own ServiceHostFactory class. Basically we create each endpoint twice. The problem is that at runtime, WCF complains that the service has two endpoints with the same contact name but with different ContractDescription instances. The message says we should use different contract names or reuse the same ContractDescription instance.

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• Making sure unsigned int/long always execute in checked context in C#

  - by theburningmonk

  Has anyone found it strange that the default context for uint and ulong is unchecked rather than checked considering that they are meant to represent values that can never be negative? So if some code is trying to violate that constraint it seems to me the natural and preferred behaviour would be to throw an exception rather than returning the max value instead (which can easily leave important pieces of data in an invalid state and impossible to revert..). Is there an existing attribute which can be applied to either class/assembly so that it always performs arithmetic operations in a checked context? I was thinking of writing one myself (as an aspect using PostSharp) but would be great if there's one already. Many thanks,

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• ImageMagick - how to enforce min/max heights/widths?

  - by Henryh

  Using ImageMagick, how can I resize an image to have a minimum: height of 150px width of 200px and also have a maximum: height of 225px width of 275px UPDATE: In case it helps, here's a further explanation of what I'm experiencing. I have a buch of images with all different ratio dimensions. Some images have 1:5 height/width ratios. Some have 5:1 height/width ratios. So that I want to do is set that a minimum height/width size for the image but also don't want the image size to be larger than a particular size. If I need to apply white padding to an image to make it fit within my constraint so that I don't have to distort the image, I'd like to do so.

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• One to two relationship in Doctrine with YAML

  - by Jeremy DeGroot

  I'm working on my first Symfony project with Doctrine, and I've run into a hitch. I'm trying to express a game with two players. The relationship I want to have is PlayerOne and PlayerTwo each being keyed to an ID in the Users table. This is part of what I've got so far: Game: actAs: { Timestampable:- } columns: id: { type: integer, notnull: true, unique: true } startDate: { type: timestamp, notnull: true } playerOne: { type: integer, notnull: true } playerTwo: { type: integer, notnull: true } winner: { type: integer, notnull:true, default:0 } relations: User: { onUpdate: cascade, local: playerOne, foreign: id} User: { onUpdate: cascade, local: playerTwo, foreign: id} That doesn't work. It builds fine, but the SQL it generates only includes a constraint for playerTwo. I've tried a few other things: User: { onUpdate: cascade, local: [playerOne, playerTwo], foreign: id} Also: User: [{ onUpdate: cascade, local: playerOne, foreign: id}, { onUpdate: cascade, local: playerTwo, foreign: id}] Those last two throw errors when I try to build. Is there anyone out there who understands what I'm trying to do and can help me achieve it?

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• Migrate a Django project from MySQL to Oracle

  - by pablo

  Hi, I have a Django1.1 project that works with a legacy MySQL db. I'm trying to migrate this project to Oracle (xe and 11g). We have two options for the migration: - Use SQL developer to create a migration sql script. - Use Django fixtures. The schema created with the sql script from sql developer doesn't match the schema created from syncdb. For example, Django expects TIMESTAMP columns while sql developer creates DATE columns. Using syncdb with Django fixtures could be great but when trying to load the MySQL fixtures into Oracle, after using syncdb, I'm getting: IntegrityError: ORA-00001: unique constraint (USER.SYS_C004253) violated How can I find what part create the integrity error? Thanks

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• Hibernate doesn't generate cascade

  - by Shervin

  Hi. I have a set hibernate.hbm2ddl.auto to create so that Hibernate creates the tables in mysql for me. However, it doesn't seem that hibernate correctly adds Cascade on the references in the table. It does however work when I for instance delete a row, and I have a delete cascade as hibernate annotation. So I guess that means that Hibernate reads the annoation on runtime, and perform cascading manually? Is that normal behavior? For instance: @Entity class Report { @OneToOne(cascade = CascadeType.ALL) public File getPdf() { return pdf; } } Here I have set cascade to ALL. However, when running show create table Report Report | CREATE TABLE `Report` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `pdf_id` bigint(20) DEFAULT NULL, PRIMARY KEY (`id`), KEY `FK91B14154FDE6543A` (`pdf_id`), CONSTRAINT `FK91B14154FDE6543A` FOREIGN KEY (`pdf_id`) REFERENCES `File` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | It doesn't say anything about cascading other then the foreign key. In my opinion, it should have added the ON DELETE CASCADE ON DELETE UPDATE

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• Why does SQL Server keep throwing exceptions?

  - by Augusto Càzares

  I have my project in .NET that uses a database in SQL Server. I'm using Linq-to-SQL, sometimes when the project throws me an exception (Constraint) in a part of the project this same error keeps showing in other part of the project when I do another thing with the database. Like when I do an insertion and I had before an exception on delete the insertion throws me the delete exception, and it remains this way until I close and open again the project. My major problem is when this happen in my online project, this error in my project causes me problems in the project I'm testing online (I use the same database). I don't know if this exception is on the memory or something but its have been causing me a lot of headaches.

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• Triangular bounding volumes

  - by Cheery

  I've come up with an alternative for beziers that might be easier to ray-trace, perhaps even though a plain vertex shader. Though there's missing a piece. I need to find the parametric surface equation from the surface normals I have for edge vertices. I also have to know it's peak and valley so I can constraint the depth of my bounding triangle. Image explains the overall idea: I build a bounding-volume from a control triangle. Then apply a function to each parametric coordinate of the triangle (s+t+u=1 where s,t,u = 0) to get the height coordinate for that certain point. Simply put, it produces a procedurally generated height-map for the triangle's surface. I just need to find a function that generates the height-map so I can make it work.

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• Sample/Example needed for a table/field setup

  - by acctman

  Can someone explain the statement below to me with a working sample/example. thanks in advance. You can not create duplicate fields, but simply add a single extra field, "coupleId", which would have a unique id for each couple; and two rows (one for each person) per couple; then JOIN the table against itself with a constraint like a.coupleId = b.coupleId AND a.id < b.id so that you can condense the data into a single result row for a given couple.

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• Data Access from single table in sql server 2005 is too slow

  - by Muhammad Kashif Nadeem

  Following is the script of table. Accessing data from this table is too slow. SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Emails]( [id] [int] IDENTITY(1,1) NOT NULL, [datecreated] [datetime] NULL CONSTRAINT [DF_Emails_datecreated] DEFAULT (getdate()), [UID] [nvarchar](250) COLLATE Latin1_General_CI_AS NULL, [From] [nvarchar](100) COLLATE Latin1_General_CI_AS NULL, [To] [nvarchar](100) COLLATE Latin1_General_CI_AS NULL, [Subject] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [Body] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [HTML] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [AttachmentCount] [int] NULL, [Dated] [datetime] NULL ) ON [PRIMARY] Following query takes 50 seconds to fetch data. select id, datecreated, UID, [From], [To], Subject, AttachmentCount, Dated from emails If I include Body and Html in select then time is event worse. indexes are on: id unique clustered From Non unique non clustered To Non unique non clustered Tabls has currently 180000+ records. There might be 100,000 records each month so this will become more slow as time will pass. Does splitting data into two table will solve the problem? What other indexes should be there?

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• Calculating Divergent Paths on Subtending Rings

  - by Russ

  I need to calculate two paths from A to B in the following graph, with the constraint that the paths can't share any edges: hmm, okay, can't post images, here's a link. All edges have positive weights; for this example I think we can assume that they're equal. My naive approach is to use Djikstra's algorithm to calculate the first path, shown in the second graph in the above image. Then I remove the edges from the graph and try to calculate the second path, which fails. Is there a variation of Djikstra, Bellman-Ford (or anything else) that will calculate the paths shown in the third diagram above? (Without special knowledge and removal of the subtending link, is what I mean)

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• T-SQL to PL/SQL (IDENTITY)

  - by folone

  I've got a T-SQL script, that converts field to IDENTITY (in a weird way). How do I convert it to PL/SQL? (and, probably, figure out, if there is a simpler way to do this - without creating a temporary table). The T-SQL script: -- alter table ts_changes add TS_THREADID VARCHAR(100) NULL; -- Change Field TS_ID TS_NOTIFICATIONEVENTS to IDENTITY BEGIN TRANSACTION GO CREATE TABLE dbo.Tmp_TS_NOTIFICATIONEVENTS ( TS_ID int NOT NULL IDENTITY (1, 1), TS_TABLEID int NOT NULL, TS_CASEID int NULL, TS_WORKFLOWID int NULL, TS_NOTIFICATIONID int NULL, TS_PRIORITY int NULL, TS_STARTDATE int NULL, TS_TIME int NULL, TS_WAITSTATUS int NULL, TS_RECIPIENTID int NULL, TS_LASTCHANGEDATE int NULL, TS_ELAPSEDCYCLES int NULL ) ON [PRIMARY] SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS ON GO IF EXISTS(SELECT * FROM dbo.TS_NOTIFICATIONEVENTS) EXEC('INSERT INTO dbo.Tmp_TS_NOTIFICATIONEVENTS (TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES) SELECT TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES FROM dbo.TS_NOTIFICATIONEVENTS WITH (HOLDLOCK TABLOCKX)') GO SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS OFF GO DROP TABLE dbo.TS_NOTIFICATIONEVENTS GO EXECUTE sp_rename N'dbo.Tmp_TS_NOTIFICATIONEVENTS', N'TS_NOTIFICATIONEVENTS', 'OBJECT' GO ALTER TABLE dbo.TS_NOTIFICATIONEVENTS ADD CONSTRAINT aaaaaTS_NOTIFICATIONEVENTS_PK PRIMARY KEY NONCLUSTERED ( TS_ID ) WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO COMMIT

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• Why MSSQL keeps throwing me Exceptions?

  - by Augusto Càzares

  I have my project in .NET that uses a db in MSSQL Server,i'm using LINQ , sometimes when the projec throws me an exception (Constraint) in a part of the project this same error keeps showing in other part of the project when i do another thing with the db, like when i do an insertion and i had before an exception on delete the insertion throws me the delete exeption, and it remainds this way until i close and open again the project, my major problem is when this happen in my online project, this error in my project causes me problems in the project i'm testing online (i use the same db). I don't know if this exception is on the memory or something but its have been causing me a lot of headechs.

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• C#: Preferred pattern for functions requiring arguments that implement two interfaces

  - by JS Bangs

  The argument to my function f() must implement two different interfaces that are not related to each other by inheritance, IFoo and IBar. I know of two different ways of doing this. The first is to declare an empty interface that inherits from both: public interface IFooBar : IFoo, IBar { // nothing to see here } public int f(IFooBar arg) { // etc. } This, of course, requires that the classes declare themselves as implementing IFooBar rather than IFoo and IBar separately. The second way is to make f() generic with a constraint: public int f<T>(T arg) where T : IFoo, IBar { // etc. } Which of these do you prefer, and why? Are there any non-obvious advantages or disadvantages to each?

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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 specify a different column for a @Inheritance JPA annotation

  - by Cue

  @Entity @Inheritance(strategy = InheritanceType.JOINED) public class Foo @Entity @Inheritance(strategy = InheritanceType.JOINED) public class BarFoo extends Foo mysql> desc foo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ mysql> desc barfoo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | | foo_id | int | | bar_id | int | +---------------+-------------+ mysql> desc bar; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ Is it possible to specify column barfo.foo_id as the joined column? Are you allowed to specify barfoo.id as BarFoo's @Id since you are overriding the getter/seeter of class Foo? I understand the schematics behind this relationship (or at least I think I do) and I'm ok with them. The reason I want an explicit id field for BarFoo is exactly because I want to avoid using a joined key (foo _id, bar _id) when querying for BarFoo(s) or when used in a "stronger" constraint. (as Ruben put it)

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• Should we use a CSS frame work ? Are they worth it ?

  - by Gaurav M

  CSS frameworks have nice styles inbuilt and ask you to focuses on the grids but still there is a bit of dependency and lack of freedom it provide.. If I need to generate a webpage by looking on a PSD based mockup screen ..either i will use the classes provided by the framework but if that actual measurements does not exist I need to again specify my own rules that will add upto my CSS filesize and if performance is a constraint as always it is...you need not a big size file..though its in kb but every drop counts. Any comments and suggestions to use the framework in a best possible way.

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• Is it a good idea to use a computed column as part of a primary key ?

  - by Brann

  I've got a table defined as : OrderID bigint NOT NULL, IDA varchar(50) NULL, IDB bigint NULL, [ ... 50 other non relevant columns ...] The natural primary key for this table would be (OrderID,IDA,IDB), but this it not possible because IDA and IDB can be null (they can both be null, but they are never both defined at the same time). Right now I've got a unique constraint on those 3 columns. Now, the thing is I need a primary key to enable transactional replication, and I'm faced with two choices : Create an identity column and use it as a primary key Create a non-null computed column C containing either IDA or IDB or '' if both columns were null, and use (OrderID,C) as my primary key. The second alternative seams cleaner as my PK would be meaningful, and is feasible (see msdn link), but since I've never seen this done anywhere, I was wondering if they were some cons to this approach.

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• MySQL Many to Many with Unique keys and Update/Select if Exists otherwise Insert

  - by Jayrox

  In my goal to have a Many-to-Many relationship in my MySQL database I have arrived at another bridge to build. Current Tables: Users (id, name) Tags (id, name) User_Tags (user_id, tag_id) Here is the goal: I would like to have the ability to take a tag i.e: #fb and insert it into my Tags database which has a unique constraint on name and if the tag exists I would like to return it's id I would like to insert the tag.id and the current user's user.id into User_Tags. I do not have any unique constraints on the User_Tags table because I would like to be able to track the user's most commonly used tags and present them in a list ordered by frequency of use. I am currently developing this project in PHP using prepared statements. Additionally, performance is not currently an issue as my user count is still fairly small, but it is steadily growing and may be an issue in the future.

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• One to One relationship in MySQL

  - by Botto

  I'm trying to make a one to one relationship in a MySQL DB. I'm using the InnoDB engine and the basic table looks like this: CREATE TABLE `foo` ( `fooID` INT(11) NOT NULL PRIMARY KEY AUTO_INCREMENT, `name` TEXT NOT NULL ) CREATE TABLE `bar` ( `barName` VARCHAR(100) NOT NULL, `fooID` INT(11) NOT NULL PRIMARY KEY, CONSTRAINT `contact` FOREIGN KEY (`fooID`) REFERENCES `foo`(`fooID`) ) Now once I have set up these I alter the foo table so that the fooID also becomes a foreign key to the fooID in bar. The only issue I am facing with this is that there will be a integrity issue when I try to insert into either. I would like some help, thanks.

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• SubSonic isn't generating MySql foreign key tables

  - by keith

  I two tables within a MySql 5.1.34 database. When using SubSonic to generate the DAL, the foreign-key relationship doesn't get scripted, ie; I have no Parent.ChildCollection object. Looking inside the generated DAL Parent class shows the following; //no foreign key tables defined (0) I have tried SubSonic 2.1 and 2.2, and various MySql 5 versions. I must be doing something wrong procedurally - any help would be greatly appreciated. This has always just worked 'out-the-box' when using MS-SQL. TABLE `parent` ( `ParentId` INT(11) NOT NULL AUTO_INCREMENT, `SomeData` VARCHAR(25) DEFAULT NULL, PRIMARY KEY (`ParentId`) ) ENGINE=INNODB DEFAULT CHARSET=latin1; TABLE `child` ( `ChildId` INT(11) NOT NULL AUTO_INCREMENT, `ParentId` INT(11) NOT NULL, `SomeData` VARCHAR(25) DEFAULT NULL, PRIMARY KEY (`ChildId`), KEY `FK_child` (`ParentId`), CONSTRAINT `FK_child` FOREIGN KEY (`ParentId`) REFERENCES `parent` (`ParentId`) ) ENGINE=INNODB DEFAULT CHARSET=latin1;

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• Copying Data between table without identity column

  - by user668479

  I have two table and I need to copy the data across from SRCServiceUsers to Clients Everytime i run it I get the following: Violation of PRIMARY KEY constraint 'PK_Clients'. Cannot insert duplicate key in object 'dbo.Clients'. The statement has been terminated. The Primary key ClientId field is not an identity column and therefore requires filling To date I have the following insert into Clients( ClientID, Title, Forenames, FamilyName, [Address], Town, County, PostCode, PhoneNumber, StartDate) SELECT ( Select Max(Clients.ClientID)+ 1, SRCServiceUsers.Title, SRCServiceUsers.[First Names], SRCServiceUsers.Surname, --BUILD UP MUITIPLE COLUMNS SRCServiceUsers.[Property Name] + ', ' + SRCServiceUsers.Street + ', ' + SRCServiceUsers.Suburb as [Address], SRCServiceUsers.Town, SRCServiceUsers.County, SRCServiceUsers.Postcode, SRCServiceUsers.Telephone, SRCServiceUsers.[Start Date] From srcsERVICEuSERS How can i autoincrement the PK field - CLientID when inserting the data? Many thanks Andrew

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• How to persist non-trivial fields in Play Framework

  - by AlexR

  I am trying to persist complex objects using Ebeans in Play Framework (2.03). In particular, I've created a class that contains a field of type weka.classifier.Classifier (Weka is a popular machine learning library - see http://weka.sourceforge.net/doc/weka/classifiers/Classifier.html). Classifier implements Serializeable so I hoped that I can get away with something like @Entity @Table(name = "classifiers") public class ClassifierData extends Model { @Id public Long id; public Classifier classifier; } However, the Evolutions script suggests the following database structure: create table classifiers ( id bigint auto_increment not null, constraint pk_classifiers primary key (id)) ) In other words, it ignores the field of type Classifier. (The database is MySQL if it makes any difference) What should I do to store complex serializeable objects using Ebean/Evolutions/PlayFramework?

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