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• How to remove duplicate records in a table?

  - by Mason Wheeler

  I've got a table in a testing DB that someone apparently got a little too trigger-happy on when running INSERT scripts to set it up. The schema looks like this: ID UNIQUEIDENTIFIER TYPE_INT SMALLINT SYSTEM_VALUE SMALLINT NAME VARCHAR MAPPED_VALUE VARCHAR It's supposed to have a few dozen rows. It has about 200,000, most of which are duplicates in which TYPE_INT, SYSTEM_VALUE, NAME and MAPPED_VALUE are all identical and ID is not. Now, I could probably make a script to clean this up that creates a temporary table in memory, uses INSERT .. SELECT DISTINCT to grab all the unique values, TRUNCATE the original table and then copy everything back. But is there a simpler way to do it, like a DELETE query with something special in the WHERE clause?

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• importing data using get or create - identity error 1062

  - by hamackey

  I am importing data from a mssql database into mysql. Works except when it encounters the id of a previous entry. id is unique. I need to get entries that already exist so that they can be placed in the work of the day. Error is IntegrityError: (1062, "Duplicate entry '001355338' for key 2") This entry is already in the database. I need it entered for that day, but can not have it added to the table. It is already there. def handle(self, *args, **options): 59 #patients_local = Patient.objects.all() 60 #attendings_local = Attending.objects.all() 61 connection = pyodbc.connect("XXXXXXXXXXX") 62 cursor = connection.cursor() 63 cursor.execute(COMMAND) 64 rows = cursor.fetchall() 65 for row in rows: 66 # get_or_create returns (object, boolean) 67 p, created = Patient.objects.get_or_create( 68 first_name = row.Firstname, 69 middle_name = '', 70 last_name = row.Lastname, 71 id = row.id, 72 )

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• What are the constraints on Cocoa Framework version numbers?

  - by Joe

  We're distributing a Cocoa framework with regular updates. We'll be updating the version numbers with each release. The Apple documentation appears to suggest that version numbers should be consecutive incrementing integers. We are distributing output in several formats, and the framework is only one of them. We would rather not have to maintain a separate numbering system just for our frameworks. We don't really care about the precise format of the version numbers of the framework, so long as they change whenever the product changes, and behave in a correct and expected manner. I'm looking for a sensible and correct way of avoiding having to run a separate version number counter. One suggestion is that for product version 12.34.56 we could simply remove the dots and say the framework version is 123456. Is there a constraint on the type of number that can be represented (uint? long?) Does it have to be a number? Could it be a string? Do the numbers have to be consecutive? Is there a standard way of doing things in this situation?

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• Indexing affects only the WHERE clause?

  - by andre matos

  If I have something like: CREATE INDEX idx_myTable_field_x ON myTable USING btree (field_x); SELECT COUNT(field_x), field_x FROM myTable GROUP BY field_x ORDER BY field_x; Imagine myTable with around 500,000 rows and most of field_x values being unique. Since I don't use any WHERE clause, will the created index have any effect at all in my query? Edit: I'm asking this question because I don't get any relevant difference between query-times before and after creating the index; They always take about 8 seconds (which, of course is too much time!). Is this behaviour expected?

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• How can I get my div id to reload via ajax and jquery

  - by Matt Nathanson

  I'm creating a CMS using jQuery and AJAX. When I click, my "Add Campaign" buttom, it creates a unique client ID in the DB and on a hard reload, the new client shows up in its container. I am trying to use ajax to reload the container on the fly and I'm not having the exact luck i am hoping for. I can get it to reload, but it's like it's pulling in descriptions of each of the clients as well! function AddNewClient() { dataToLoad = 'clientID=' + clientID + '&addClient=yes'; $.ajax({ type: 'post', url: '/clients/controller.php', datatype: 'html', data: dataToLoad, target: ('#clientssidebar'), async: false, success: function(html){ $('#clientssidebar').html(html); }, error: function() { alert('An error occured!'); } }); };

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• Deserialization of a DataSet... deal with column name changes? how to migrate data from one column to another?

  - by Brian Kennedy

  So, we wanted to slightly generalize a couple columns in our typed dataset... basically dropped a foreign key constraint and then wanted to change a couple column names to better reflect their new state. All that is easy. The problem is that our users may have serialized out the old version of the DataSet as XML. We want to be able to read those old XML files and deserialize them into the revised DataSet. It seems that would be a fairly common desire... but I haven't yet figured out the right thing to search the internet for. One possible solution would seem to be some way to give a DataColumn an alias or alternate name such that when it reads the old column name, it knows that data can be read into the column with the new column name. I can find no support for any such thing. Another approach would seem to be an "after deserialization" method of some sort... so, I would let it read in the old column values into a normal DataColumn with that name, and then in the "after deserialization" method I would just move the data from the obsolete column into the new column, and then delete the old columns. That would seem to generalize to many other situations... and having such events or hooks is pretty common in ADO.NET. But I have looked for such a hook and haven't yet found it. If no "after deserialization" hook, it would seem I ought to be able to override ReadXml or ReadXmlSerializable methods to call the base and then do my "after" stuff to fix up old data into new. But it does not appear that is possible. Soooo, I have to think backward compatibility with old serialized DataSets and simple data migration would be a well-solved problem... so, trying to reinvent that wheel seems silly. But so far, I haven't seemed to find any documentation on doing those things. Suggestions? What is best practice for this?

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• Database Design Question: GUID + Natural Numbers

  - by Alan

  For a database I'm building, I've decided to use natural numbers as the primary key. I'm aware of the advantages that GUID's allow, but looking at the data, the bulk of row's data were GUID keys. I want to generate XML records from the database data, and one problem with natural numbers is that I don't want to expose my database key's to the outside world, and allow users to guess "keys." I believe GUID's solve this problem. So, I think the solution is to generate a sparse, unique iD derived from the natural ID (hopefully it would be 2-way), or just add an extra column in the database and store a guid (or some other multibyte id) The derived value is nicer because there is no storage penalty, but it would be easier to reverse and guess compared to a GUID. I'm (buy) curious as to what others on SO have done, and what insights they have.

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• Batch processing JDBC

  - by Wai Hein

  I am practicing JDBC batch processing and having errors: error 1: Unsupported feature error 2: Execute cannot be empty or null Property files include: itemsdao.updateBookName = Update Books set bookname = ? where books.id = ? itemsdao.updateAuthorName = Update books set authorname = ? where books.id = ? I know I can execute about DML statements in one update, but I am practicing batch processing in JDBC. Below is my method public void update(Item item) { String query = null; try { connection = DbConnector.getConnection(); property = SqlPropertiesLoader.getProperties("dml.properties"); connection.setAutoCommit(false); if ( property == null ) { Logging.log.debug("dml.properties does not exist. Check property loader or file name is spelled right"); return; } query = property.getProperty("itemsdao.updateBookName"); statement = connection.prepareStatement(query); statement.setString(1, item.getBookName()); statement.setInt(2, item.getId()); statement.addBatch(query); query = property.getProperty("itemsdao.updateAuthorName"); statement = connection.prepareStatement(query); statement.setString(1, item.getAuthorName()); statement.setInt(2, item.getId()); statement.addBatch(query); statement.executeBatch(); connection.commit(); }catch (ClassNotFoundException e) { Logging.log.error("Connection class does not exist", e); } catch (SQLException e) { Logging.log.error("Violating PK constraint",e); } //helper class th finally { DbUtil.close(connection); DbUtil.closePreparedStatement(statement); }

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• Django and a referrer system question

  - by Hellnar

  Hello, I am trying develop a basic referrer system to my Django website, system will be generating a unique url for each users to share with their friends. Once these friends enter this website, system somehow keep the data that "this user is browsing by the reference of X user" and once this invited person decided to register for an account, system will save this information (maybe as an extra Foreign Key of the inviting user in the UserProfile model) Now how can I keep track of the inviting user from the moment entering using the referred link to the point where he/she registers to the site. Would session framework work on this? If not how could this be done ?

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• Windows Mobile application icon

  - by Andy White

  Is it possible to specify the application icon for a windows mobile app from a resource file or other configuration besides the .csproj? The reason I would like to do this is because I have an application that can be configured to run in several different ways. We would like to build out three unique .cabs based on these configurations, and we would like to use a different icon for each version. One option we've considered is just running multiple builds and swapping out the icon file each time, but we were hoping there would be a way to do this using a "resource" DLL or something along those lines, that could be compiled or linked in to the main .exe.

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• Hibernate Auto-Increment not working

  - by dharga

  I have a column in my DB that is set with Identity(1,1) and I can't get hibernate annotations to work for it. I get errors when I try to create a new record. In my entity I have the following. @GeneratedValue(strategy=GenerationType.IDENTITY, generator="native") @Column(name="SeqNo", unique=true, nullable=false) BigDecimal seqNo; But when I try to add a new record I get the following error. Cannot insert explicit value for identity column in table 'MemberSelectedOptions' when IDENTITY_INSERT is set to OFF. I don't want to set IDENTIY_INSERT to ON because I want the identity column in the db to manage the values. The SQL that is run is the following; where you can clearly see the insert. insert into dbo.MemberSelectedOptions (OptionStatusCd, EffectiveDate, TermDate, SelectionStatusDate, SysLstUpdtUserId, SysLstTrxDtm, SourceApplication, GroupId, MemberId, OptionId, SeqNo) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) What am I missing?

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• What Can A 'TreeDict' (Or Treemap) Be Used For In Practice?

  - by Seun Osewa

  I'm developing a 'TreeDict' class in Python. This is a basically a dict that allows you to retrieve its key-value pairs in sorted order, just like the Treemap collection class in Java. I've implemented some functionality based on the way unique indexes in relational databases can be used, e.g. functions to let you retrieve values corresponding to a range of keys, keys greater than, less than or equal to a particular value in sorted order, strings or tuples that have a specific prefix in sorted order, etc. Unfortunately, I can't think of any real life problem that will require a class like this. I suspect that the reason we don't have sorted dicts in Python is that in practice they aren't required often enough to be worth it, but I want to be proved wrong. Can you think of any specific applications of a 'TreeDict'? Any real life problem that would be best solved by this data structure? I just want to know for sure whether this is worth it.

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• WPF custom user widgets. Will UI components be standardized?

  - by Andrew Florko

  There are lots of articles and video lessons that describe how to create your unique user widget (graphical control) with WPF. There are tons of technical details what is behind the scene and I feel people enthusiasm with ability to customize widgets as never before. I remember those days when VCL library (Delphi) appeared and there was the same enthusiasm in VCL widgets area. Ability to create VCL controls was nearly the must when you was applying for a job as Delphi developer. This situation continued for several years till professional sophisticated 3'd party UI libraries appeared. Hardly you'll have to create your own VCL widget nowadays. Will WPF widgets enthusiasm die as VCL one?

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• Command Query Separation validating for retries

  - by Neil Barnwell

  So I'm comfortable with the basic concept of CQS, where you might have a command that writes to one database, and that updates the query database that you read from. However, consider the scenario where you are entering data, and want to prevent duplicates. Using new employee data entry an employee register as an example, working through a pile of application forms to key in the new employees' details: Take top sheet. Key in employee name and unique payroll number to UI. Submit. Put paper in "completed pile". Repeat. How would you now prevent the user from keying in the same payroll number again, say for instance if they get distracted and can't remember whether they've keyed one in already and the "message" hasn't got all the way back to the query db for the user to search?

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• PHP/Codeigniter processing a list with javascript

  - by user270797

  I have a list of items that the user can select. I want it to be more user friendly than standard checkboxes so I have seperate div's each with a unique id. When user clicks an item, I use javascript to display a tick on top of that item and change the style to show that it is highlighted. Im trying to work out how I can pass the list of id's when the form is submitted. Remember, if the user unticks an item, it should be removed from the list, I was thinking of using comma seperated values in a hidden text field but couldnt work out how to remove items from the start of the list if they were deselected

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• How to map it? HasOne x References

  - by Felipe

  Hi everyones, I need to make a mapping One by One, and I have some doubts. I have this classes: public class DocumentType { public virtual int Id { get; set; } /* othes properties for documenttype */ public virtual DocumentConfiguration Configuration { get; set; } public DocumentType () { } } public class DocumentConfiguration { public virtual int Id { get; set; } /* some other properties for configuration */ public virtual DocumentType Type { get; set; } public DocumentConfiguration () { } } A DocumentType object has only one DocumentConfiguration, but it is not a inherits, it's only one by one and unique, to separate properties. How should be my mappings in this case ? Should I use References or HasOne ? Someone could give an example ? When I load a DocumentType object I'd like to auto load the property Configuration (in documentType). Thanks a lot guys! Cheers

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• Reuse C++ Header files

  - by Amrish

  Guys, I have a Visual C++ solution with 2 projects AlgorithmA & AlgorithmB and both share a common header file RunAlgo.h with the class declaration. Each project in the solution has its own unique implementation for the header file. I am trying to compile a DLL out of the common header file RunAlgo.h and add reference to this DLL in the projects AlgorithmA & AlgorithmB. I have then included separate RunAlgo.cpp definition file in both my projects. The problem is that I am getting linker errors while compiling the new DLL project which has only the header file. So, the question is Can a header file with only class declaration be compiled into a DLL (Similar to class library containing an Interface in C#)? For the above scenario, is there a better approach to reuse the common Header file among projects? Should the above method work (re-check my code?)

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• Select one column from a row in hibernate

  - by ComfortablyNumb

  I am trying to do a simple query to get a unique result back in hibernate here is my code. public String getName(Integer id) { Session session = getSessionFactory().openSession(); String name = (String)session.createSQLQuery("SELECT name FROM users WHERE user_id = :userId").setParameter("userId", id).uniqueResult(); return name; } The name that is being returned is stored as HTML text that includes html syntacx language. I think this is what is causing the problem but it doesnt make sense I just want to return it as a string. It is only happening on this one field name, I can get every other field in the row but this one it gives me the error. I am getting an exception. The exception I am getting is No Dialect mapping for JDBC type: -1; nested exception is org.hibernate.HibernateException How do you query for a specific column on a row in hibernate?

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• On counting pairs of words that differ by one letter

  - by Quintofron

  Let us consider n words, each of length k. Those words consist of letters over an alphabet (whose cardinality is n) with defined order. The task is to derive an O(nk) algorithm to count the number of pairs of words that differ by one position (no matter which one exactly, as long as it's only a single position). For instance, in the following set of words (n = 5, k = 4): abcd, abdd, adcb, adcd, aecd there are 5 such pairs: (abcd, abdd), (abcd, adcd), (abcd, aecd), (adcb, adcd), (adcd, aecd). So far I've managed to find an algorithm that solves a slightly easier problem: counting the number of pairs of words that differ by one GIVEN position (i-th). In order to do this I swap the letter at the ith position with the last letter within each word, perform a Radix sort (ignoring the last position in each word - formerly the ith position), linearly detect words whose letters at the first 1 to k-1 positions are the same, eventually count the number of occurrences of each letter at the last (originally ith) position within each set of duplicates and calculate the desired pairs (the last part is simple). However, the algorithm above doesn't seem to be applicable to the main problem (under the O(nk) constraint) - at least not without some modifications. Any idea how to solve this?

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• django: Selecting questions that was not asked

  - by Oleg Tarasenko

  Hi, I am creating small django application which holds some few questions (and answers for them) What I want to do is to show user random question, but only from those which was not solved by him yet. I wonder how to do this. For now, I defined user profile model this way: class UserProfile(models.Model): rank = models.IntegerField(default = 1) solvedQ = models.ManyToManyField(Question) user = models.ForeignKey(User, unique=True) So solved problems are added this way: if user.is_authenticated(): profile = user.get_profile() profile.rank += 1 profile.solvedQ.add(Question.objects.get(id=id)) Now if the view must show random question, but not from already solved list... Is there a good way to intersect Questions and solvedQuestions.... so question is chosen from the unsolved list?

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• How to determine ASP.NET's generated ID's from codebehind?

  - by Matthew Scharley

  In ASP.NET, when you give a tag an ID it generates a unique HTML id for the element based on the control hierachy, ie. <asp:Panel ID="test" runat="server"> ... </asp:Panel> <!-- Becomes... --> <div id="plc_lt_zoneContent_PagePlaceholder_PagePlaceholder_lt_test_test"> ... </div> Is there some way of determining the generated id in the codebehind file? I need to generate some Javascript that uses the id.

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• Qlikview joins that dosen't join on all matching column names

  - by Dev_Karl

  Hi! I'm new to Qlikview and looking for some answers regarding scripting. How can I create Qlickview joins that just join on a specific column (and not all that are having a matching name)? Let's say that I'm having the following tables: Employee Id | Person | DepartmentID | Flags 1000 , Bob , 2001 , 1000000 1001 , Sue , 2002 , 1100000 Department Id | Name | Flags 2001 , HR , 01101111 2001 , R&D , 1100000 What is the best way of joining those tables on the DepartmentID <- ID field? The data is provided by SQL selects. I'm thinking of writing SQL views using unique names would be one idea, but there must be a simpler way. Please advice Kind regards, Karl

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• NHibernate: Dynamically swapping a single domain model between multiple physical data models

  - by Nigel

  Hi In this article Ayende describes how to map a single domain model to multiple physical data models. Is it possible to extend this principle such that the mapping can chosen dynamically? So for example, imagine we had an entity that could be written to the same physical schema in three ways depending on its current status, and lets assume that regardless of status each entity had a unique identifier. One solution would be to represent the entity in its different states with three separate classes: one for each mapping. Then the entity could be loaded and in order to change its state the entity could be mapped to a class representing one of its other states and then saved back to the schema, making use of a different mapping. I was wondering if it is at all possible to have the same entity represented by one class that held a status flag (kind of like a discriminator), and any save to the schema would choose the appropriate mapping based on the value of the status flag. Hopefully that made sense! Many thanks.

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• .Net Round-trip Types

  - by Fujiy

  I making a method that generate a unique string key for some parameters. But the same key if call with same values. I just accept primitive types, string, DateTime, Guid, and Nullable(since I append types together, I can distinguish who is int and who is int?), because I can convert all to string without lost values or precision.(for float and double a use ToString("R"), to DateTime ToString("O")). Exists a easy way to know which types I can transform in strings without conflict? And how do this transform(how I said before, float, double and datetime have specific ways) Thanks

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• What's the best way to implement one-dimensional collision detection?

  - by cyclotis04

  I'm writing a piece of simulation software, and need an efficient way to test for collisions along a line. The simulation is of a train crossing several switches on a track. When a wheel comes within N inches of the switch, the switch turns on, then turns off when the wheel leaves. Since all wheels are the same size, and all switches are the same size, I can represent them as a single coordinate X along the track. Switch distances and wheel distances don't change in relation to each other, once set. This is a fairly trivial problem when done through brute force by placing the X coordinates in lists, and traversing them, but I need a way to do so efficiently, because it needs to be extremely accurate, even when the train is moving at high speeds. There's a ton of tutorials on 2D collision detection, but I'm not sure the best way to go about this unique 1D scenario.

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