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• JPA 2.0 EclipseLink Check for unique

  - by Parhs

  Hello... I have a collumn as unique=true.. in Exam class.... I found that because transactions are commited automaticaly so to force the commit i use em.commit() However i would like to know how to check if it is unique.Running a query isnt a solution because it may be an instert after checking because of the concurency.... Which is the best way to check for uniqness? List<Exam_Normal> exam_normals = exam.getExam_Normal(); exam.setExam_Normal(null); try { em.persist(exam); em.flush(); Long i = 0L; if (exam_normals != null) { for (Exam_Normal e_n : exam_normals) { i++; e_n.setItem(i); e_n.setId(exam); em.persist(e_n); } } } catch (Exception e) { System.out.print("sfalma--"); } } d

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• Unique ID for WORD2007 paragraph

  - by Ganish

  Hello, I am writing large WORD2007 socuments, which are often being changed. I ahve to number paragraphs with stationary unique unmbers, that will not change while changing the documents. The numbers should be unique, and will not change even if previous numbers are deleted. The order of the list is not mandatory, and addition of a new number before existing numbers is possible (for instance: the sequence 1, 4, 3 means that paragraphs 1-3 were written, then #2 was deleted, then #5 was added. #3 was not affected by the later editing) The mechanism should be internal to the document, as I am working on line and off line. The numbers are allocated to every document indovidually. Since I don't know to program under WORD, I'd appreciate getting complete solution. REgards Ganish

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• DDD - Validation of unique constraint

  - by W3Max

  In DDD you should never let your entities enter an invalid state. That being said, how do you handle the validation of a unique constraint? The creation of an entity is not a real problem. But let say you have an entity that must have a unique name and there is a thousand instances of this entity type - they are not in memory but stored in a database. Now let say you want to rename an instance. You can't just use a setter... the object could enter an invalid state - you have to validate against the database. How do you handle this scenario in a web environment?

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• MySQL unique clustered constraint not constraining as expected

  - by igor

  I'm creating a table with: CREATE TABLE movies ( id INT AUTO_INCREMENT PRIMARY KEY, name CHAR(255) NOT NULL, year INT NOT NULL, inyear CHAR(10), CONSTRAINT UNIQUE CLUSTERED (name, year, inyear) ); (this is jdbc SQL) Which creates a MySQL table with a clustered index, "index kind" is "unique", and spans the three clustered columns: full size However, once I dump my data (without exceptions thrown), I see that the uniqueness constraint has failed: SELECT * FROM movies WHERE name = 'Flawless' AND year = 2007 AND inyear IS NULL; gives: id, name, year, inyear 162169, 'Flawless', 2007, NULL 162170, 'Flawless', 2007, NULL Does anyone know what I'm doing wrong here?

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• Unique ID Defined by Most-Derived Class accessible through Base Class

  - by Narfanator

  Okay, so, the idea is that I have a map of "components", which inherit from componentBase, and are keyed on an ID unique to the most-derived*. Only, I can't think of a good way to get this to work. I tried it with the constructor, but that doesn't work (Maybe I did it wrong). The problem with any virtual, etc, inheritance tricks are that the user has to impliment them at the bottom, which can be forgotten and makes it less... clean. *Right phrase? If - is inheritance; foo is most-derived: foo-foo1-foo2-componentBase Here's some code showing the problem, and why CRTP can't cut it: (No, it's not legit code, but I'm trying to get my thoughts down) #include<map> class componentBase { public: virtual static char idFunction() = 0; }; template <class T> class component : public virtual componentBase { public: static char idFunction(){ return reinterpret_cast<char>(&idFunction); } }; class intermediateDerivations1 : public virtual component<intermediateDerivations1> { }; class intermediateDerivations2 : public virtual component<intermediateDerivations2> { }; class derived1 : public intermediateDerivations1 { }; class derived2 : public intermediateDerivations1 { }; //How the unique ID gets used (more or less) std::map<char, componentBase*> TheMap; template<class T> void addToMap(componentBase * c) { TheMap[T::idFunction()] = c; } template<class T> T * getFromMap() { return TheMap[T::idFunction()]; } int main() { //In each case, the key needs to be different. //For these, the CRTP should do it: getFromMap<intermediateDerivations1>(); getFromMap<intermediateDerivations2>(); //But not for these. getFromMap<derived1>(); getFromMap<derived2>(); return 0; } More or less, I need something that is always there, no matter what the user does, and has a sortable value that's unique to the most-derived class. Also, I realize this isn't the best-asked question, I'm actually having some unexpected difficultly wrapping my head around it in words, so ask questions if/when you need clarification.

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• Unique user ID in a Pylons web application

  - by John Smith

  What is the best way to create a unique user ID in Python, using UUID?

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• need to generate unlimited number of unique id's with jQuery

  - by jquery n00b

  Hi all, extreme n00b here... I've got a number of elements (dynamically generated by back end so it could be quite a few) and all need a unique id. I'm trying to work out how to do this wth jQuery and not doing so well. Any help is appreciated. In the code below, I'd want each "bar" div to get a unique id, like id1, id2 etc etc <div class="foo"> <ul class="bar"> </ul> <ul class="bar"> </ul> <ul class="bar"> </ul> <ul class="bar"> </ul> </div>

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• Returning unique values of a multi-dimensional array with CodeIgniter PHP

  - by Michael Bradley

  Hi - I'm developing a property rentals website. The search results page will contain a list of property results. It is my intention to redefine the results, say by town, country, property type etc. So let's say for example the user searches 'France'. All of the relative properties will be returned and displayed in a list. However, I also need to reuse this array, to display only unique town names from the search results array. e.g. Montpellier, Lyon, Rennes, Nice etc. The idea is when use user click on 'Nice', only the 'Nice' properties would return. I would also like to display how many properties are in that town. The closest example as to what I want to achieve. http://www.miaandmaggie.com/dog-collars-leashes.html Any ideas how I can use my search array to display the unique towns of the search? Many thanks! M

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• Getting USB Storage Device Instance ID (unique ID) programmatically

  - by Navaneeth

  Whenever user plug a USB mass storage device, how to get the Device Instance ID (unique ID) of that particular device programmatically?

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• Grails- Unique and Null

  - by WaZ

  The problem I have noticed is: Grails ignores nulls in unique constraints.

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• Finding One record from table having unique PK and duplicate FK

  - by Muhammad Kashif Nadeem

  I want one record from a table having unique Primary Key and duplicate Foreign Key Please see attached image below Thanks

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• Unique keys for Sphinx along three vectors instead of two

  - by Brendon Muir

  I'm trying to implement thinking-sphinx across multiple 'sites' hosted under a single rails application. I'm working with the developer of thinking-sphinx to sort through the finer details and am making good progress, but I need help with a maths problem: Usually the formula for making a unique ID in a thinking-sphinx search index is to take the id, multiply it by the total number of models that are searchable, and add the number of the currently indexed model: id * total_models + current_model This works well, but now I also through an entity_id into the mix, so there are three vextors for making this ID unique. Could someone help me figure out the equation to gaurantee that the id's will never collide using these three variables: id, total_models, total_entities The entity ID is an integer. I thought of: id * (total_models + total_entities) + (current_model + current_entity) but that results in collisions. Any help would be greatly appreciated :)

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• Removing duplicate SQL records to permit a unique key

  - by j pimmel

  I have a table ('sales') in a MYSQL DB which should have rightfully have had a unique constraint enforced to prevent duplicates. To first remove the dupes and set the constraint is proving a bit tricky. Table structure (simplified): 'id (unique, autoinc)' product_id The goal is to enforce uniqueness for product_id. The de-duping policy I want to apply is to remove all duplicate records except the most recently created, eg: the highest id Or to put another way, I would like to delete duplicate records, excluding the ids matched by the following query: select id from sales s inner join (select product_id, max(id) as maxId from sales group by product_id having count(product_id) > 1) groupedByProdId on s.product_id and s.id = groupedByProdId.maxId I've struggled with this on two fronts - writing the query to select the correct records to delete and then also the constraint in MYSQL where a subselect FROM clause of a DELETE cannot reference the same table from which data is being removed.

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• SQL Get Latest Unique Rows

  - by Simpleton

  I have a log table, each row representing an object logging its state. Each object has a unique, unchanging GUID. There are multiple objects logging their states, so there will be thousands of entries, with objects continually inserting new logs. Everytime an object checks in, it is via an INSERT. I have the PrimaryKey, GUID, ObjectState, and LogDate columns in tblObjects. I want to select the latest (by datetime) log entry for each unique GUID from tblObjects, in effect a 'snapshot' of all the objects. How can this be accomplished?

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• Finding unique elements in an string array in C

  - by LuckySlevin

  Hi, C bothers me with its handling of strings. I have a pseudocode like this in my mind: char *data[20]; char *tmp; int i,j; for(i=0;i<20;i++) { tmp = data[i]; for(j=1;j<20;j++) { if(strcmp(tmp,data[j]))//then except the uniqueness, store them in elsewhere. } } But when i coded this the results were bad.(I handled all the memory stuff,little things etc.) The problem is in the second loop obviously :D. But i cannot think any solution. How do i find unique strings in an array. Example input : abc def abe abc def deg entered unique ones : abc def abe deg should be found.

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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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• Unique serial number in a java web application.

  - by Zenzen

  I've been wondering what's the correct practice for generating unique ids? The thing is in my web app I'll have a plugin system, when a user registers a plugin I want to generate a unique serial ID for it. I've been thinking about storing all numbers in a DB or a file on the server, generating a random number and checking whether it already exists in the DB/file, but that doesn't seem that good. Are there other ways to do it? Would using the UUID be the preferred way to go?

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• speed up calling lot of entities, and getting unique values, google app engine python

  - by user291071

  OK this is a 2 part question, I've seen and searched for several methods to get a list of unique values for a class and haven't been practically happy with any method so far. So anyone have a simple example code of getting unique values for instance for this code. Here is my super slow example. class LinkRating2(db.Model): user = db.StringProperty() link = db.StringProperty() rating2 = db.FloatProperty() def uniqueLinkGet(tabl): start = time.time() dic = {} query = tabl.all() for obj in query: dic[obj.link]=1 end = time.time() print end-start return dic My second question is calling for instance an iterator instead of fetch slower? Is there a faster method to do this code below? Especially if the number of elements called be larger than 1000? query = LinkRating2.all() link1 = 'some random string' a = query.filter('link = ', link1) adic ={} for itema in a: adic[itema.user]=itema.rating2

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• Get Item from Collection by unique ID

  - by David Murdoch

  I have a collection of Contacts that inherits from CollectionBase: public class ContactCollection : CollectionBase{ //... } each contact in the collection has a unique ID: public class Contact{ public int ContactID{ get; private set; } //... } I think what I would like to do is something like the following: // get the contact by their unique [Contact]ID Contact myPerson = Contact.GetContactById(15); // get all contacts for the customer ContactCollection contacts = customer.GetContacts(); // replaces the contact in the collection with the // myPerson contact with the same ContactID. contacts.ReplaceAt(myPerson); // saves the changes to the contacts and the customer // customer.Save(); There is probably a better way...if so, please suggest it.

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• How to generate unique ID in clustering

  - by Samina Shaikh

  Is there any clustering API that helps in generating the unique ID across many servers?

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• Specifying a unique control name when adding at runtime (like the VS IDE)

  - by user316383

  hi, I have a basic IDE for a user control i am building. It allows me to add labels to a panel and move them around, like a very basic form designer. When I add the controls to the panel at runtime, I'd like to give the control a unique name string like how the VS IDE tracks the controls it already has and adds an extra number when it creates the default control name. I have tried checking the controls collection each time a new control is added, but wasnt sure if there was a good string comparison method to return a name with a unique number on the end that hasn't been used yet.

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• Do encryption algorithms provide really unique results?

  - by Mikulas Dite

  I was wondering whether md5, sha1 and anothers return unique values. For example, sha1() for test returns a94a8fe5ccb19ba61c4c0873d391e987982fbbd3, which is 40 characters long. So, sha1 for strings larger than 40 chars must be the same (of course it's scrambled, because the given input may contain whitespaces and special chars etc.). Due to this, when we are storing users' passwords, they can enter either their original password or some super-long one, which nobody knows. Is this right, or do these hash algorithms provide really unique results - I'm quite sure it's hardly possible.

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• Interesting or unique types encountered?

  - by user318904

  What is the most strange or unique type you have seen in a programming language? I was thinking the other day about a "random variable", ie whenever it is evaluated it yields a random value from some domain. It would require some runtime trickery. Also I bet there can be some interesting mapping of regular expressions into a type system. It does not necessarily have to be a built in or primitive type, but some random class that implements a domain specific type won't really be interesting just unique.

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• Add Unique Key For Nullable Columns - SQL Server

  - by Ruby

  I'm using sql server 2008 R2 and would like to apply unique key constraint to nullable columns. This code works good, but if I have multiple columns to add this rule to, it would generate as many 'nullbuster' columns. ALTER TABLE tblBranch ADD nullbuster AS (CASE WHEN column1 IS NULL THEN BranchID ELSE NULL END); CREATE UNIQUE INDEX UK_Column1 ON tblBranch(column1,nullbuster); tblBranch is the table name, nullbuster would be the new column name, BranchId is the Primary key column of the target table, and Column1 is the column name of the target column. Is there any way that I could achieve the goal without generating new columns.

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• Trying to get unique records with MySQL

  - by Joshmattvander

  I have a query that is looking at a 'page_views' table. And I so far have the ability to get the total views by day. However, I am having an issue with getting unique views by day. The column I am testing against is user_id... Here's the query I have for total views. SELECT site_id, CONCAT(month(created_at) , '-', day(created_at), '-' , year(created_at)) as created_at_date, COUNT(*) as total_results FROM page_views GROUP BY day(created_at) I can't figure out the logic to just get the unique views, by day based on the user_id column though.

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