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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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  • Question about mysql indexes on low to medium cardinality columns

    - by Kevin J
    I have a general question about the way that database indexing works, particularly in mysql. Let's say I have a table with a million rows with a column "ClientID" that is distributed relatively equally among 30 values. Thus, this column is very low cardinality (30) relative to the primary key (1 million). Now, I understand that you shouldn't create indexes on low cardinality fields. However, in this case, queries are only ever done with one of the 30 clientIDs. Thus, wouldn't creating an index on ClientID be helpful, as the search space is automatically reduced to 1/30th what it normally would be? Or is my understanding of how the index works flawed? Thanks

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  • Windows Sharepoint Service (WSS) 3.0 search Issue

    - by dewacorp.alliances
    Based on this http://servergrrl.blogspot.com/2008/02/how-to-use-wss-30-to-search-more-than.html blog, I've created a domain account for testing and sets the permission at the side level as well as Document Library to allow specific user (DOMAIN/TestUser1) allow accessing this folder. Now, it's interesting that the user can see the document by drilling though BUT it won't be able to search and the document couldn't find it. But if I tested with the site owner (both primary and secondary), it works nicely. What did I do wrong then? It must be related on permission but I cound't work out what it is. BTW ... I am using WSS not MOSS 2007. Thanks

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  • The most elegant way to encapsulate WinAPI callbacks inside a class

    - by FractalizeR
    Hello. I am thinking about elegant way to encapsulate WinAPI callbacks inside a class. Suppose I am making a class handling asynchronous I/O. All Windows callbacks should be stdcall functions, not class methods (I need to pass their addresses to ReadFileEx WinAPI function for example). So, I cannot just pass method addresses as a callback routines to WinAPI functions. What is the most elegant way to encapsulate functionality of this type inside a class so that the class have events OnReadCompleted and OnWriteCompleted (I am using Delphi as a primary language, but I guess the situation must be the same in C++ because class methods are different from simple methods by the fact, that the first hidden parameter of them is this link. Of course this class is not a singleton and there can be many of them created by app at the same time. What do you think would be the good way to implement this?

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  • Please help me to write the sql

    - by Lu Lu
    Hello everyone, I am a new with T-SQL. So, please help me to write the sql. I have table Price (Code column is primary column): Code Value A1 234 A2 525 A3 566 I will input a string and the sql need to return a table. Ex1: input 'A2' - return: Code Value A2 525 Ex2: input 'A1 A3' - return: Code Value A1 234 A3 566 Ex3: input 'A1 A3 A1' - return: Code Value A1 234 A3 566 Ex4: input 'A1 A4' - return: Code Value A1 234 Please help me. I am using SQL Server 2005. Tks.

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  • How to optimize this user ranking query

    - by James Simpson
    I have 2 databases (users, userRankings) for a system that needs to have rankings updated every 10 minutes. I use the following code to update these rankings which works fairly well, but there is still a full table scan involved which slows things down with a few hundred thousand users. mysql_query("TRUNCATE TABLE userRankings"); mysql_query("INSERT INTO userRankings (userid) SELECT id FROM users ORDER BY score DESC"); mysql_query("UPDATE users a, userRankings b SET a.rank = b.rank WHERE a.id = b.userid"); In the userRankings table, rank is the primary key and userid is an index. Both tables are MyISAM (I've wondered if it might be beneficial to make userRankings InnoDB).

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  • How to save array of integer numbers in a column in SQL Server 2005

    - by hamed
    I have a table in SQL Server 2005 with the following properties: Users (UserID, Username, Password) where UserID is primary key I want to save an array of integer numbers in the password attribute in the Users table. -------------------- 0 1 2 3 -------------------- 1543 6543 7658 8765 -------------------- I plan to save this into the password column. On the other hand I use pictures instead of texts for password and each picture has a code (4 digit) and a password include 4 picture that produce 16 digit. I want to save these 16 digits (array of Ints) into the Password column please help me. thanks

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  • mysql query - syntax error - cannot find out why

    - by Phil Jackson
    Hi all, im taring my hair out over this one. A query is throwing an error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974101', 'fa' at line 1 I printed out the query to see what could be the problem: INSERT INTO db.tablename ( FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974299', 'false', 'dfdsfdsfd' ) and finaly the structure consists of: CREATE TABLE db.tablename ( `ID` int(12) NOT NULL auto_increment, `FROM` varchar(255) NOT NULL, `SUBJECT` varchar(255) NOT NULL, `DATE` varchar(255) NOT NULL, `READ` varchar(255) NOT NULL, `MAIL` varchar(255) NOT NULL, PRIMARY KEY (`ID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; I cant find anything wrong. Any Help would be much appreciated. ( db.tablename is a replacement for the actual tablename )

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  • Network Load Balancing (NLB): is it suitable for "stateful" ASP.NET applications?

    - by micha12
    Hi everybody, I have posted the following question concerning ASP.NET web farms. http://stackoverflow.com/questions/1816756/how-to-create-an-asp-net-web-farm/ Guys recommended using Network Load Balancing (NLB) as a primary way of creating a web farm. However, Wikipedia says that "NLBS is intended for ... stateless applications". Our web application, however, is absolutely "stateful": it is a closed site to which users will have access by login and password, and information for every user will be different: people will see their own trades and operations. Should we still use NLB in this scenario? Thank you.

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  • How to model my database when using entity framework 4?

    - by Junior Ewing
    Trying to wrap my head around the best approach in modelling a database when we are using Entity Framework 4 as the ORM layer. We are going to use asp.net mvc 2 for the application. Is it worth trying to model using the class diagram modeller that comes with Visual Studio 2010 where you graphically configure your models into the EDMX file and then generate out the database structure? I have run into a bunch of non trivial issues and for complex many to many mappings or multi primary key entities the answer is not that obvious even after poking around a while with the tools. I figure its easy at this point to give up and start modelling the DB using real, working DB modelling tools and then try to generate out the EDMX from the database, rather than trying to do the model first approach.

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  • Prevent Casual Piracy for Simple Utility

    - by Chad
    I've written a small utility that I wish to sell for less than $10. My primary concern is "casual piracy". The scenario that plays out in my mind is this: User buys the program, enjoys using it and tells their friends. The friends copy the application to their USB drives and take it home - using the application for free (maybe never realizing they should have purchased it. Since I've got absolutely no protection built in, it would just be a simple copy'n paste to pirate the app. The users who would be using the app are in close proximity to each other (work in the same environment), so casual piracy would likely occur frequently. Any ideas? Keeping in mind the app is cheap (partly to reduce casual piracy), and the level of effort to write the app hasn't been very demanding. Update: the app will run on any system that supports .NET 3.5.

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  • Why is autorelease especially dangerous/expensive for iPhone applications?

    - by e.James
    I'm looking for a primary source (or a really good explanation) to back up the claim that the use of autorelease is dangerous or overly expensive when writing software for the iPhone. Several developers make this claim, and I have even heard that Apple does not recommend it, but I have not been able to turn up any concrete sources to back it up. SO references: autorelease-iphone Why does this create a memory leak (iPhone)? Note: I can see, from a conceptual point of view, that autorelease is slightly more expensive than a simple call to release, but I don't think that small penalty is enough to make Apple recommend against it. What's the real story?

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  • Copying Some from a PostgreSQL Server to Another

    - by whollychao
    I am in need of an application that can periodically transmit select rows from a PostgreSQL database across a network to a second PostgreSQL server. Typically these will be the most recent row added, pulled and transmitted every 10-30 seconds. The primary servers run in a MS Windows environment with a high-latency, and occasionally intermittent, network connection. Therefore, any application would have to be tolerant of this and ideally automatically reconnect / resend data that could not be transmitted. Due to the environment and the requirements, a full-blown replication package would be unnecessary. I appreciate any help anyone has with this problem.

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  • Using sizeof operator on a typedef-ed struct

    - by sskanitk
    This might be something too obvious. However, I couldn't find the specific answer though many stackoverflow threads talk about different aspects of this. typedef struct _tmp { unsigned int a; unsigned int b; } tmp; int main() { int c=10; if (c <= sizeof tmp) { printf("less\n"); } else { printf("more\n"); } return 0; } I compile this prog as - g++ -lstdc++ a.cpp I get an error - expected primary-expression before ‘)’ token I think I am missing something very obvious and straightforward. But can't seem to pinpoint it :-/ Thanks!

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  • SQL Server - Error when trying to reference a .mdf file

    - by Amokrane
    Hi, For a NUnit test I need to reference a .mdf file from a .config file. Unfortunately, I get the following error message: The FOR ATTACH option requires that at least the primary file be specified. An attempt to attach an auto-named database for file C:\....\*.mdf A database with the same name exists, or specified file cannot be opened, or it is located on UNC share. I looked for this error on google but didn't find anything that helped me solve my problem. Any idea? Thank you

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  • Does php mvc framework agavi use CRUD compliant to REST?

    - by txwikinger
    The agavi framework uses the PUT request for create and POST for updating information. Usually in REST this is used the other way around (often referring to POST adding information while PUT replacing the whole data record). If I understand it correctly, the important issue is that PUT must be idempotent, while POST does not have this requirement. Therefore, I wounder how creating a new record can be idempotent (i.e. multiple request do not lead to multiple creations of a record) in particular when usually the ORM uses an id as a primary key and the id of a new record would not be known to the client (since it is autocreated in the database), hence cannot be part of the request. How does agavi maintain the requirement of idempotence in light of this for the PUT request. Thanks.

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  • What is the worst class/variable/function name you have ever encountered

    - by Chris Noe
    Naming things well is arguably Job 1 for professional programmers. Yet we have all suffered from some bad naming choices from time to time. So just to vent a little, what are some doozies that you may have run across? Just to get things started: One of our original developers wasn't sure what to call a secondary key - on what turned out to be a primary table for this app - so he called it: DL2WhateverTheHellThatIs. Unfortunately this system generates entity mappings from the XML, and attributes defined there result in classes, methods, and constants that are referenced through-out the app. To this day it is very hard to find a source file that does not reference this, er, thing! A few actual examples: DL2WhateverTheHellThatIsBean cos = (DL2WhateverTheHellThatIsBean)itr.next(); String code = getDL2WhateverTheHellThatIs().getCode(); From from = new From("DL2WhateverTheHellThatIs"); String filter = "_dL2WhateverTheHellThatIs._code"; (Very difficult to refactor)

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  • IN statement performance in PostgreSQL (and in general)

    - by Vasil
    I know this has probably been asked before, but I can't find it with SO's search. Lets say i've TABLE1 and TABLE2, who should I expect the performance of a query such as this: SELECT * FROM TABLE1 WHERE id IN SUBQUERY_ON_TABLE2; as the number of rows in TABLE1 and TABLE2 grow and id is a primary key on TABLE1. Yes, I know using IN is such a n00b mistake, but TABLE2 has a generic relation (django generic relation) to multiple other tables so I can't think of another way to filter the data. At what (aproximate) ammount of rows in TABLE1 and TABLE2 should I expect to notice performance issues because of this? Will performance degrade linearly, exponentially etc. depending on the number of rows?

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  • Getting "stack level too deep" error when deploying with Capistrano, Rails 3.1 ruby 1.9.2

    - by Victor S
    Here is the log for the cap deploy script output around where the error occurs. Anny suggestions why this might be happening? Thanks! [yup.la] executing command [yup.la] sh -c 'cd /srv/www/portrait/releases/20120406051647 && bundle exec rake RAILS_ENV=production RAILS_GROUPS=assets assets:precompile' ** [out :: yup.la] rake aborted! ** [out :: yup.la] ** [out :: yup.la] stack level too deep ** [out :: yup.la] (in /srv/www/portrait/releases/20120406051647/app/assets/stylesheets/mobile.css.scss) ** [out :: yup.la] ** [out :: yup.la] Tasks: TOP => assets:precompile:primary ** [out :: yup.la] (See full trace by running task with --trace) ** [out :: yup.la] command finished in 30868ms *** [deploy:update_code] rolling back * executing "rm -rf /srv/www/portrait/releases/20120406051647; true" servers: ["yup.la"] [yup.la] executing command [yup.la] sh -c 'rm -rf /srv/www/portrait/releases/20120406051647; true' command finished in 288ms failed: "sh -c 'cd /srv/www/portrait/releases/20120406051647 && bundle exec rake RAILS_ENV=production RAILS_GROUPS=assets assets:precompile'" on yup.la /Users/victorstan/Sites/portrait ?

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  • How do I chain forms in Access? (pass values between them)

    - by jeff porter
    Hello, I'm using Access 2007 and have a data model like this... Passenger - Bookings - Destinations So 1 Passenger can have Many Bookings, each for 1 Destinations. My problem... I can create a form to allow the entry of Passenger details, but I then want to add a NEXT button to take me to a form to enter the details of the Booking (i.e. just a simple drop list of the Destinations). I've added the NEXT button and it has the events of RunCommand SaveRecord OpenForm Destination_form BUT, I cant work out how to pass accross to the new form the primary key of the passenger that was just entered (PassengerID). I'd really like to have just one form, and that allow the entry of the Passenger details and the selection of a Destination, that then creates the entries in the 2 Tables (Passenger & Bookings), but I can't get that to work either. Can anyone help me out please? Thanks Jeff Porter

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  • declaring constraint to consider prog logic

    - by shantanuo
    I can open a trip only once but can close it multiple times. I can not declare the Trip_no + status as primary key since there can be multiple entries while closing the trip. Is there any way that will assure me that a trip number is opened only once? For e.g. there should not be the second row with "Open" status for trip No. 3 since it is already there in the following table. Trip No | Status 1 Open 1 Close 1 Close 2 Open 2 Close 3 Open 3 Close 3 Close 3 Close 3 Close

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  • Mysql partition error?

    - by drake
    I have a kinda table like this: CREATE TABLE test ( id MEDIUMINT NOT NULL AUTO_INCREMENT, user VARCHAR(30), time VARCHAR(30), status VARCHAR(30), origin VARCHAR(30), PRIMARY KEY (id) ) ENGINE=MyISAM; PARTITION BY RANGE(id) ( PARTITION p0 VALUES LESS THAN (500000), PARTITION p1 VALUES LESS THAN (1000000), PARTITION p2 VALUES LESS THAN (1500000), PARTITION p3 VALUES LESS THAN (2000000), PARTITION p4 VALUES LESS THAN (2500000) ) I have Three questions: 1) I have here an #1064 error; 2) How can i set split test.user as alphabetic range in partition; 3) How can i check that the partition was successful;

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  • SQL GROUP BY with "default values"

    - by Christoph Schiessl
    I'm trying to create SELECT statement with a GROUP BY clause, which should return "default values". Imagine the following simple MySQL table: CREATE TABLE `tracker` ( `id` INTEGER PRIMARY KEY auto_increment, `date` DATETIME NOT NULL, `customer_id` INTEGER NOT NULL ); The table contains only one record: INSERT INTO `tracker` (`date`, `customer_id`) VALUES('2010-05-03', 1); After wards I'm executing the following SQL query: SELECT DATE(`date`), COUNT(customer_id) FROM tracker WHERE DATE(`date`) >= '2010-05-01' AND DATE(`date`) <= '2010-05-05' GROUP BY DATE(`date`) ORDER BY DATE(`date`); And get the expected result set: +----+---------------------+-------------+ | id | date | customer_id | +----+---------------------+-------------+ | 1 | 2010-05-10 00:00:00 | 1 | +----+---------------------+-------------+ However, I would like the result set to look like this: +--------------+--------------------+ | DATE(`date`) | COUNT(customer_id) | +--------------+--------------------+ | 2010-05-01 | 0 | | 2010-05-02 | 0 | | 2010-05-03 | 1 | | 2010-05-04 | 0 | | 2010-05-05 | 0 | +--------------+--------------------+ Is it possible to achieve this behavior?

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  • Select row data as ColumnName and Value

    - by Bobcat1506
    I have a history table and I need to select the values from this table in ColumnName, ColumnValue form. I am using SQL Server 2008 and I wasn’t sure if I could use the PIVOT function to accomplish this. Below is a simplified example of what I need to accomplish: This is what I have: The table’s schema is CREATE TABLE TABLE1 (ID INT PRIMARY KEY, NAME VARCHAR(50)) The “history” table’s schema is CREATE TABLE TABLE1_HISTORY( ID INT, NAME VARCHAR(50), TYPE VARCHAR(50), TRANSACTION_ID VARCHAR(50)) Here is the data from TABLE1_HISTORY ID NAME TYPE TRANSACTION_ID 1 Joe INSERT a 1 Bill UPDATE b 1 Bill DELETE c I need to extract the data from TABLE1_HISTORY into this format: TransactionId Type ColumnName ColumnValue a INSERT ID 1 a INSERT NAME Joe b UPDATE ID 1 b UPDATE NAME Bill c DELETE ID 1 c DELETE NAME Bill Other than upgrading to Enterprise Edition and leveraging the built in change tracking functionality, what is your suggestion for accomplishing this task?

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  • InvalidOperationException sequence contains more than one element even when only one element

    - by user310256
    I have three tables, tblCompany table, tblParts table and a link table between them tblLinkCompanyParts. Since tblLinkCompanyParts is a link table so the columns that it has are LinkCompanyPartID(primary key), CompanyID from tblCompany table and PartID from tblParts as foreign keys. I have tied them up in the dbml file. In code if I write LinkCompanyParts.Parts (where LinkCompanyParts is an object of the tblLinkCompanyParts type) to get to the corresponding Part object I get the "InvalidOperationException: Sequence constains more than one element". I have looked at the data in the database and there is only one Parts record associated with the LinkCompanyPartID. The stack trace reads like at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source) at System.Data.Linq.EntityRef`1.get_Entity() at ... I read about SingleOrDefault vs FirstOrDefault but since the link table should have a one-one mapping therefore I think SingleOrDefault should work and besides "SingleOrDefault" statement is being generated behind the scenes in the designer.cs file at the following line return this._Part.Entity; Any ideas?

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