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• How to order the items in a nested LINQ-provided collection

  - by Carson McComas

  I've got a (SQL Server) database table called Category. And another database table called SubCategory. SubCategory has a foreign key relationship to Category. Because of this, thanks to LINQ, each Cateogory has a property called SubCategories and LINQ is nice enough to return all the SubCategories associated with my Category when I grab it. If I want to sort the Categories alphabetically, I can just do: return db.Categories.OrderBy(c => c.Name); However, I have no idea how to order the SubCategories collection inside each Category. My goal is to return a collection of Categories, where all of the SubCategory collections inside of them are ordered alphabetically by Name.

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• What arguments to use to explain why SQL Server is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• SQLAlchemy - how to map against a read-only (or calculated) property

  - by Jeff Peck

  I'm trying to figure out how to map against a simple read-only property and have that property fire when I save to the database. A contrived example should make this more clear. First, a simple table: meta = MetaData() foo_table = Table('foo', meta, Column('id', String(3), primary_key=True), Column('description', String(64), nullable=False), Column('calculated_value', Integer, nullable=False), ) What I want to do is set up a class with a read-only property that will insert into the calculated_value column for me when I call session.commit()... import datetime def Foo(object): def __init__(self, id, description): self.id = id self.description = description @property def calculated_value(self): self._calculated_value = datetime.datetime.now().second + 10 return self._calculated_value According to the sqlalchemy docs, I think I am supposed to map this like so: mapper(Foo, foo_table, properties = { 'calculated_value' : synonym('_calculated_value', map_column=True) }) The problem with this is that _calculated_value is None until you access the calculated_value property. It appears that SQLAlchemy is not calling the property on insertion into the database, so I'm getting a None value instead. What is the correct way to map this so that the result of the "calculated_value" property is inserted into the foo table's "calculated_value" column?

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• How do I hide data/field in a List in J2ME

  - by pi

  Hi, I am working on a J2ME app which has dynamically generated Lists. Items on this list may be consequently selected, and the selection processed within the commandAction block. Is there a way to have the IDs of variables populating the List (from a remote database) included in the List item definition as in: this.append("A", null); this.append("B", null); or: String[] arrayOfValues = {"A", "B"}; new List("Menu", List.IMPLICIT, arrayOfValues, null); such that when an item is selected, perhaps A, I can also have its database ID for perhaps further processing. Is it possible to hide a field/data? Thanks.

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• When should I open and close a connection to SQL Server

  - by Martin

  I have a simple static class with a few methods in it. Each of those methods open a SqlConnection, query the database and close the connection. This way, I am sure that I always close the connection to the database, but on the other hand, I don't like to always open and close connection. Below is an example of what my methods look like. public static void AddSomething(string something) { using (SqlConnection connection = new SqlConnection("...")) { connection.Open(); // ... connection.Close(); } } Considering that the methods are inside a static class, should I have a static member containing a single SqlConnection? How and when should I drop it? What are the best practices?

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• How would you start automating my job? - Part 2

  - by Jurily

  (Followup to this question) After surviving the first wave of incoming shipments (9 hours of copy/paste), I now believe I have all the requirements. Here is the updated workflow: Monkey collects email attachments (4 Excel spreadsheets, 1 PDF) Monkey creates central database, does complex calculations (right now this is also an Excel spreadsheet) Monkey sends data to two bosses, who set the retail prices independently; first one to reply wins Monkey sends order form to our other warehouses, also Excel Monkey sends spreadsheets to VIP customers, carefully sanitized and formatted (4 different discount categories) Jurily enters the data into the accounting system. I've given up on automating this part, there's too much business logic involved, and the database is a pile of sh^W legacy My question: What technologies would you use for a quick and dirty solution? I'm mostly sold on C#, but coming from a Linux/C++ background, I'm horribly confused about my choices in Microsoft-land. For bonus points: How would you redesign the whole system from the ground up? P.S. in case you were wondering, my job title is System Administrator.

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• IIS 7 Can't read data from ASP.Net application services tables

  - by vikp

  Hi, I'm working on deploying a web application written in C# with ASP.Net Application services databases. The application runs fine on the development machine. Windows Server 2003 has been built to test the application. The database has been scripted across using MS SQL Server GUI. ASP.Net application services tables were created using an utility. The connection strings are stored in the web.config and connectionStrings.config. The application connects to the database successfully, but then it times out after 10 seconds.

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• How can I display characters in a map by mapfile?

  - by sirius

  Hello. I'm trying to show a map using postGIS+Mapserver.And I've displayed a PNG picture in my WEB. However, I want to show some charactors in the map, just like this: this is the example from Mapserver Now I'm using database(postgreSQL), but not a shape file. How can I add the charactors then? Here is a part of my mapfile: LAYER CONNECTIONTYPE postgis NAME "state" //Connect to a remote spatial database CONNECTION "user=postgres dbname=*** host=*** password=***" PROCESSING "CLOSE_CONNECTION=DEFER" DATA "the_geom from province" STATUS ON TYPE POLYGON CLASS STYLE COLOR 122 122 122 OUTLINECOLOR 0 0 0 END LABEL COLOR 132 31 31 SHADOWCOLOR 218 218 218 SHADOWSIZE 2 2 TYPE TURETYPE FONT arial-bold SIZE 12 ANTIALIAS TRUE POSITION CL PARTIALS FALSE MINDISTANCE 300 BUFFER 4 END END Some said adding a "TEXT ([*])" in "LABEL", but I don't know howto? Thanks for your help!

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• Most elegant way to morph this sequence

  - by Ed Woodcock

  Hi folks: I've got the Day of the week stored in a database table (that I do not control), and I need to use it in my code. Problem is, I want to use the System.DayOfWeek enum for representation for this, and the sequences are not the same. In the database, it's as follows: 1 2 3 4 5 6 7 S M T W T F S I need it as follows: 0 1 2 3 4 5 6 M T W T F S S What's the most elegant way to do this? for example, I could do: i = dayOfWeek; i = i - 2; if (i < 0) { i = 6; } but that's a bit inelegant. Any suggestions?

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• the MVCC effect on migration from oracle to db2

  - by Ryan Fernandes

  I have a simple (actually simplified :) ) scenario that is possibly the cause for the headache I've been having for the last few days... My current application (that serves 100's of users) currently uses Oracle as the database. I have no stored procs (I wish actually). Now, I've been asked if the product will work if I migrate to IBM DB2 as the database. So, after taking Oracle for granted all this while.... and having re-read Tom's article on MVCC (Multiversion Concurrency Control) and going through this post stating that DB2 is not 'on the list' or 'just tip-toeing in the area' as it were... I know I can't be sure that the product will work with DB2 as is. Is there no hope.. or is there a nice disclaimer I could use.. ?

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• Creating a triple store query using SQL - how to find all triples that have a common predicate and o

  - by Ankur

  I have a database that acts like a triple store, except that it is just a simple MySQL database. I want to select all triples that have a common predicate and object. Info about RDF and triples I can't seem to work out the SQL. If I had just a single predicate and object to match I would do: select TRIPLE from TRIPLES where PREDICATE="predicateName" and OBJECT="objectName" But if I have a list (HashMap) of many pairs of (predicateName,objectName) I am not sure what I need to do. Please let me know if I need to provide more info, I am not sure that I have made this quite clear, but I am wary of providing too much info and confusing the issue.

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• How to maintain unique login in windows form application?

  - by Vivek

  Hello All, I am developing a winform application in which user's login is validated through ms sql server 2000 database.When user entry its user name and password, application checks its exists in user table or not. Now my requirement is if a user already login through one system it should not log in through another system. if solution like make entry in database about status of user like on successful log in mark user status is true and on closing application mark false , then in the case of network or hardware failure or system exception. so, please suggest me a optimal solution .

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• How do I get the position of a result in the list after an order_by?

  - by Bob Bob

  I'm trying to find an efficient way to find the rank of an object in the database related to it's score. My naive solution looks like this: rank = 0 for q in Model.objects.all().order_by('score'): if q.name == 'searching_for_this' return rank rank += 1 It should be possible to get the database to do the filtering, using order_by: Model.objects.all().order_by('score').filter(name='searching_for_this') But there doesn't seem to be a way to retrieve the index for the order_by step after the filter. Is there a better way to do this? (Using python/django and/or raw SQL.) My next thought is to pre-compute ranks on insert but that seems messy.

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• How to isolate data per customer, Django powered website

  - by Sawwy

  I have recently started learning python and django and working on a project that includes building a website for collecting information from customers. I am currently trying to figure out best way to isolate the customer data (collected information is sensitive and should only be accessible by customer and the service provider). I found this post Postgresql - one database for everyone, or one-database per customer and my question is that can I automate the model inheritance with customer creation via admin? To be specific, when save() is called for adding customer via django admin, this should create the customer specific tables (create a new set of tables with 'company_name' -prefix). For more information of the environment, I have extended the basic user registration with custom UserProfile adding 'company' and 'role' fields for each user. Upon login, the 'company' of the user will be checked to filter out tables without the 'company_name' prefix. 'Role' will further filter the which company-specific tables and set rights (view, edit). will appreciate any suggestions if more elegant methods could be used to solve the data isolation problem than model inheritance.

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• Linking Excel and Access

  - by Mel

  I run a sports program where i have a master roll of who is in which class in excel. I want to link this to a database in access that stores the other information about each athlete, e.g. address, parents name, school, medical details. I want to be able to add names to class in the excel speadsheet and have this automatically generate a record for that person in access. There also needs to be some failsafe for athletes that are in multiple classes. I was also doing class roles as pivot tables out of the access database so i need to code for classes and also have this allow for athletes in multiple classes/disciplines.

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• trying to use ActiveRecord with Sinatra, Migration fails question

  - by David Lazar

  Hi, running Sinatra 1.0, I wanted to add a database table to my program. In my Rakefile I have a task task :environment do ActiveRecord::Base.establish_connection(YAML::load(File.open('config/database.yml'))["development"]) end I have a migration task in my namespace that calls the migration code: namespace :related_products do desc "run any migrations we may have in db/migrate" task :migrate => :environment do ActiveRecord::Migrator.migrate('db/migrate', ENV["VERSION"] ? ENV["VERSION"].to_i : nil ) end My console pukes out an error when the call to ActiveRecord::MIgrator.migrate() is made. rake aborted! undefined method `info' for nil:NilClass The migration code itself is pretty simple... and presents me with no clues as to what this missing info class is. class CreateStores < ActiveRecord::Migration def self.up create_table :stores do |t| t.string :name t.string :access_url t.timestamps end end def self.down drop_table :stores end end I am a little mystified here and am looking for some clues as to what might be wrong. Thanks!

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• mysql - how do I load data from a different configuration...

  - by Ronedog

  I'm not sure if this will make sense, but I'll give it a shot. My hard drive went down and I had to reinstall the os along with all my webserver configuration,etc. I kept a backup of the mysql database, but it doesn't contain all the tables...I added a couple tables after my last backup. I have access to the hard drive and the directory where the mysql data files are stored from the failed hard drive, but I don't know how to retrieve the data into my new mysql database. Is it even possible to get the raw data files from mysql and load them into a different instance? I'd even be happy if there was some way for phpmyadmin to show the data files, then I could dump out to a backup txt file, and reload them into my new configuration. Any help will be appreciated. thanks.

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• Quicken like Windows Forms application

  - by WinFXGuy

  Hi All, I need to build a quicken like application, where data needs to be secure. I don't see any database being used by Quicken. I could use XML, MDF or Access database, but data is not secure in the tables. What is the best option? How does Quicken handle it? My application may also have document attachments as well. The functionality of this application is similar to quicken but not an accounting/financial in functionality. Thanks a bunch!

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• Are there Python ORMs out there that support multiple independent databases concurrently in use?

  - by sdt

  I'm writing an application in Python where I wish to use sqlite as the backing store for documents edited by the app, with documents generally living in memory, but being saved to disk-based databases when the application saves. Ideally I'd like to use something like an ORM to make access to the data from my Python application code simple. Unfortunately it seems like the majority of Python ORMs, including SQLAlchemy, SQLObject, Django, and Storm, associate the database connection (or engine or whatever) with the classes representing table data, rather than instances of those classes. This restricts these ORMs to working with a single database connection across all instances. Since I'd like to support having multiple documents open simultaneously, this isn't going to work for me. Are there any ORMs out there that support this usage model in Python? Bazaar seems to support this, but it's quite out of date, and at first glance appears to have some other shortcomings. Thanks for any suggestions!

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• Working with hibernate/DAO problems

  - by Gandalf StormCrow

  Hello everyone here is my DAO class : public class UsersDAO extends HibernateDaoSupport { private static final Log log = LogFactory.getLog(UsersDAO.class); protected void initDao() { //do nothing } public void save(User transientInstance) { log.debug("saving Users instance"); try { getHibernateTemplate().saveOrUpdate(transientInstance); log.debug("save successful"); } catch (RuntimeException re) { log.error("save failed", re); throw re; } } public void update(User transientInstance) { log.debug("updating User instance"); try { getHibernateTemplate().update(transientInstance); log.debug("update successful"); } catch (RuntimeException re) { log.error("update failed", re); throw re; } } public void delete(User persistentInstance) { log.debug("deleting Users instance"); try { getHibernateTemplate().delete(persistentInstance); log.debug("delete successful"); } catch (RuntimeException re) { log.error("delete failed", re); throw re; } } public User findById( java.lang.Integer id) { log.debug("getting Users instance with id: " + id); try { User instance = (User) getHibernateTemplate() .get("project.hibernate.Users", id); return instance; } catch (RuntimeException re) { log.error("get failed", re); throw re; } } } Now I wrote a test class(not a junit test) to test is everything working, my user has these fields in the database : userID which is 5characters long string and unique/primary key, and fields such as address, dob etc(total 15 columns in database table). Now in my test class I intanciated User added the values like : User user = new User; user.setAddress("some address"); and so I did for all 15 fields, than at the end of assigning data to User object I called in DAO to save that to database UsersDao.save(user); and save works just perfectly. My question is how do I update/delete users using the same logic? Fox example I tried this(to delete user from table users): User user = new User; user.setUserID("1s54f"); // which is unique key for users no two keys are the same UsersDao.delete(user); I wanted to delete user with this key but its obviously different can someone explain please how to do these. thank you

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• How to implement a syndication receiver? (multi-client / single server)

  - by LeonixSolutions

  I have to come up with a system architecture. A few hundred remote devices will be communicating over internet with a central server which will receive data and store it in a database. I could write my own TCP/IP based protocol use SOAP use AJAX use RSS anything else? This is currently seen as one way (telemetry, as opposed to SCADA). Would it make a difference if we make it bi-directional. There are no plans to do so, but Murphy's law makes me wary of a uni-directional solution (on the data plane; I imagine that the control plane is bi-directional in all solutions (?)). I hope that this is not too subjective. I would like a solution which is quick and easy to implement and for others to support and where the general "communications pipeline" from remote deceives to database server can be re-used as the core of future projects. I have a strong background in telecomms protocols, in C/C++ and PHP.

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• What can I do about a SQL Server ghost FK constraint?

  - by rcook8601

  I'm having some trouble with a SQL Server 2005 database that seems like it's keeping a ghost constraint around. I've got a script that drops the constraint in question, does some work, and then re-adds the same constraint. Normally, it works fine. Now, however, it can't re-add the constraint because the database says that it already exists, even though the drop worked fine! Here are the queries I'm working with: alter table individual drop constraint INDIVIDUAL_EMP_FK ALTER TABLE INDIVIDUAL ADD CONSTRAINT INDIVIDUAL_EMP_FK FOREIGN KEY (EMPLOYEE_ID) REFERENCES EMPLOYEE After the constraint is dropped, I've made sure that the object really is gone by using the following queries: select object_id('INDIVIDUAL_EMP_FK') select * from sys.foreign_keys where name like 'individual%' Both return no results (or null), but when I try to add the query again, I get: The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "INDIVIDUAL_EMP_FK". Trying to drop it gets me a message that it doesn't exist. Any ideas?

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• OOP function and if statement

  - by Luke

  Not sure if I can ask two questions? If i run the following function in my database class function generateUserArray() { $u = array(); $result = $this->selectAllUsers(); while( $row=mysql_fetch_assoc($result)) { $u[] = $row['username']; } return $u; } Would i call it like this? $u[] = $datebase->generateUserArray(); My second question, will this work: else if($database->addLeagueInformation($subname, $subformat, $subgame, $subseason, $subwindow, $subadmin, $subchampion, $subtype) && $databases->addLeagueTable($name) && $_SESSION['players'] == $subplayers && $comp_name = "$format_$game_$name_$season" && $_SESSION['comp_name'] = $comp_name) Thankyou

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• Large ResultSet on postgresql query

  - by tuler

  I'm running a query against a table in a postgresql database. The database is on a remote machine. The table has around 30 sub-tables using postgresql partitioning capability. The query will return a large result set, something around 1.8 million rows. In my code I use spring jdbc support, method JdbcTemplate.query, but my RowCallbackHandler is not being called. My best guess is that the postgresql jdbc driver (I use version 8.3-603.jdbc4) is accumulating the result in memory before calling my code. I thought the fetchSize configuration could control this, but I tried it and nothing changes. I did this as postgresql manual recomended. This query worked fine when I used Oracle XE. But I'm trying to migrate to postgresql because of the partitioning feature, which is not available in Oracle XE. My environment: Postgresql 8.3 Windows Server 2008 Enterprise 64-bit JRE 1.6 64-bit Spring 2.5.6 Postgresql JDBC Driver 8.3-603

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• Finding Cities within 'X' Kilometers (or Miles)

  - by Mike Curry

  This may or may not be clear, leave me a comment if I am off base, or you need more information. Perhaps there is a solution out there already for what I want in PHP. I am looking for a function that will add or subtract a distance from a longitude OR latitude value. Reason: I have a database with all Latitudes and Longitudes in it and want to form a query to extract all cities within X kilometers (or miles). My query would look something like this... Select * From Cities Where (Longitude > X1 and Longitude < X2) And (Latitude > Y1 and Latitude < Y2) Where X1 = Longitude - (distance) Where X2 = Longitude + (distance) Where Y1 = Latitude - (distance) Where Y2 = Latitude + (distance) I am working in PHP, with a MySql Database. Open to any suggestions also! :)

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