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  • Ruby on Rails: building a model with an attribute not in the database?

    - by randombits
    I have a model that sets one of its attributes based off of a form parameter that a user submits. The model is a child resource to a parent resource Home. A hypothetical example is the following: A class Person has an age attribute. The user submits a birthdate as an HTTP POST parameter and from that, I need to derive the age of the user. So I'd do something like this: @home.people.build(:name => params[:name], :birthdate => params[:birthdate]) Rails would barf on that for obvious reasons, complaining it doesn't know what the attribute birthdate is. What's the proper way of going about this? Is it possible to use the build constructor with the supplied solution so that my foreign key relations are also setup properly? If not, what's a better way to work around this problem?

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  • Designing DAL in .NET to be "data-source independent" and not just "database independent" ?

    - by Munish Goyal
    How to design such flexible DAL (specifically in .NET) ? What interfaces .NET provides and what should be done on my own ? Its a greenfield project starting with SQL Server as data source but in future, parts of it will move to different NoSQL type of datastores. Also, we may need to experiment with lot of different datastores (like some data may have to go with Cassandra, some with RDBMS, some to other DHT etc.) Therefore easily switchable access layer will be needed. All i know right now is the 'data' and 'operations needed on that data'.

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  • Is saving to database just to get an ID a bad hack?

    - by Narsil
    I hope the title is not too confusing. I am trying to make folders with linq-to-sql objects' IDs. Actually I have to create folders before I should save them. I will use them to keep user uploaded files. As you can see I have to create the folder with the FileID before I can save it there. So I just save a record which will be edited or maybe deleted File newFile = new File(); ...//add some values to fields so they don't throw rule violations db.AddFile(newFile); db.Save(); System.IO.Directory.CreateDirectory("..Uploads/"+newFile.FileId.ToString()); After that I will have to edit some fields and save again. Of course user might stop upload and I would have to delete it. I know I can write a stored procedure to get the next available FileID but some other upload happening at the same time would get the same number. So they would write in same directory which is a thing I don't want. Should I go on with this, would there be some problems? Can you think of a better way?

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  • Is Django's manage.py syncdb or South used to create the test database?

    - by Thierry Lam
    With Django 1.1.1 and South 0.62, running a test from the CLI usually have the following output: Creating table some_model Installing index for my_app.SomeModel model . ----- Ran 1 test in 1s OK After upgrading to South 0.7, the output is invoking South's migration: Creating table some_model Installing index for my_app.SomeModel model Migrating... Running migrations for my_app: - Migrating forwards to 0001_initial > my_app:0001_initial - Loading initial data for my_app Migrated: - my_app . ----- Ran 1 test in 1s OK To create the test DB, has the test always used South migration in the past(before South 0.7) even if the output is not explicitly being shown?

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  • KODO: how set up fetch plan for bidirectional relationships?

    - by BestPractices
    Running KODO 4.2 and having an issue inefficient queries being generated by KODO. This happens when fetching an object that contains a collection where that collection has a bidrectional relationship back to the first object. Class Classroom { List<Student> _students; } Class Student { Classroom _classroom; } If we create a fetch plan to get a list of Classrooms and their corresponding Students by setting up the following fetch plan: fetchPlan.addField(Classroom.class,”_students”); This will result in two queries (get the classrooms and then get all students that are in those classrooms), which is what we would expect. However, if we include the reference back to the classroom in our fetch plan in order for the _classroom field to get populated by doing fetchPlan.addField(Student.class, “_classroom”), this will result in X number of additional queries where X is the number of students in each classroom. Can anyone explain how to fix this? KODO already has the original Classroom objects at the point that it's executing the queries to retrieve the Classroom objects and set them in each Student object's _classroom field. So I would expect KODO to simply set those objects in the _classroom field on each Student object accordingly and not go back to the database. Once again, the documentation is sorely lacking with Kodo/JDO/OpenJPA but from what I've read it should be able to do this more efficiently. Note-- EAGER_FETCH.PARALLEL is turned on and I have tried this with caching (query and data caches) turned on and off and there is no difference in the resultant queries.

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  • Inconsistent MySQL COLLATE errors across databases

    - by Teflon Ted
    I have two physically-separate MySQL databases on which I have to run a single query. The query has a section of SQL that looks like this: and foo_table.bar_column like concat('%', rules.pattern, '%') COLLATE utf8_general_ci It runs fine on database A but on database B I get this error: ERROR 1253 (42000): COLLATION 'utf8_general_ci' is not valid for CHARACTER SET 'latin1' If I remove the collation it runs fine on database B but on database A I get this error: ERROR 1267 (HY000): Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation 'like' Is there a version of the query that will run on both databases? Or, is there a configuration I can change on either database to make the query happy in both places? Update: Database A is version 5.1.38, Database B is version 5.1.34

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  • How to store array data in MySQL database using PHP & MySQL?

    - by Cyn
    I'm new to php and mysql and I'm trying to learn how to store the following array data from three different arrays friend[], hair_type[], hair_color[] using MySQL and PHP an example would be nice. Thanks Here is the HTML code. <input type="text" name="friend[]" id="friend[]" /> <select id="hair_type[]" name="hair_type[]"> <option value="Hair Type" selected="selected">Hair Type</option> <option value="Straight">Straight</option> <option value="Curly">Curly</option> <option value="Wavey">Wavey</option> <option value="Bald">Bald</option> </select> <select id="hair_color[]" name="hair_color[]"> <option value="Hair Color" selected="selected">Hair Color</option> <option value="Brown">Brown</option> <option value="Black">Black</option> <option value="Red">Red</option> <option value="Blonde">Blonde</option> </select> <input type="text" name="friend[]" id="friend[]" /> <select id="hair_type[]" name="hair_type[]"> <option value="Hair Type" selected="selected">Hair Type</option> <option value="Straight">Straight</option> <option value="Curly">Curly</option> <option value="Wavey">Wavey</option> <option value="Bald">Bald</option> </select> <select id="hair_color[]" name="hair_color[]"> <option value="Hair Color" selected="selected">Hair Color</option> <option value="Brown">Brown</option> <option value="Black">Black</option> <option value="Red">Red</option> <option value="Blonde">Blonde</option> </select> Here is the MySQL tables below. CREATE TABLE friends_hair ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, hair_id INT UNSIGNED NOT NULL, user_id INT UNSIGNED NOT NULL, PRIMARY KEY (id) ); CREATE TABLE hair_types ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, friend TEXT NOT NULL, hair_type TEXT NOT NULL, hair_color TEXT NOT NULL, PRIMARY KEY (id) );

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  • How to ask database server for current datetime using entity framework?

    - by Levelbit
    I don't want for my current ModifeidDateTime to be machine time already server time. Every time I want to update or add a person to my datebase on SQL Server 2008 I want to fill ModifiedDateTime filed. It's not like I can change update query as with data adapter command when I work with dataset and to define for my ModifiedDateTime filed to be =GetDate(). I created stored function to retutn me a value of GetDate() method, but I have a problem to import procedure which returns values as int, string ... or no value at all, already just entity values as Person for example in my case. Why is that? Anyway, It would be of great help if you can provide me any solution that works to retrieve DateTime value from server.

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  • How can I optimize the SELECT statement running on an Oracle database?

    - by Elvis Lou
    I have a SELECT statement in ORACLE: SELECT COUNT(DISTINCT ds1.endpoint_msisdn) multiple30, dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status) subscription_status FROM daily_summary ds1 join daily_summary ds2 ON ds1.endpoint_msisdn = ds2.endpoint_msisdn, daily_summary_static dss1, daily_summary_static dss2, (SELECT NULL subscription_status FROM dual UNION ALL SELECT -2 subscription_status FROM dual) x WHERE ds1.summary_ts >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND ds1.summary_ts <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss1.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss2.last_active >= To_date('10-04-2012', 'dd-mm-yyyy') - 30 AND dss2.last_active <= To_date('10-04-2012', 'dd-mm-yyyy') AND dss1.service <> dss2.service AND ( dss1.company_scope = 2 OR dss1.company_scope = 5 ) AND ( dss2.company_scope = 2 OR dss2.company_scope = 5 ) AND dss1.company_scope = dss2.company_scope AND ds1.endpoint_noc_id = dss1.endpoint_noc_id AND ds1.endpoint_host_id = dss1.endpoint_host_id AND ds1.endpoint_instance_id = dss1.endpoint_instance_id AND ds2.endpoint_noc_id = dss2.endpoint_noc_id AND ds2.endpoint_host_id = dss2.endpoint_host_id AND ds2.endpoint_instance_id = dss2.endpoint_instance_id AND dss1.endpoint_provisioning_id = dss2.endpoint_provisioning_id AND Least(1, ds1.total_actions) = 1 AND Least(1, ds2.total_actions) = 1 GROUP BY dss1.service, dss1.endpoint_provisioning_id, dss1.company_scope, Nvl(x.subscription_status, dss1.subscription_status); This query took about 26 minutes to return in my environment, but if I remove the section: dss1.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss1.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND dss2.last_active >= to_date('10-04-2012','dd-mm-yyyy') - 30 AND dss2.last_active <= to_date('10-04-2012','dd-mm-yyyy') AND it only took 20 seconds to run. We have index on the column last_active, I don't know why the section slow down the performance so much? any ideas?

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  • MySQL app with Cassandra in mind

    - by SODA
    I am planning to make a web app which will eventually use Cassandra. But now that I don't have it and don't have server(s) to run it from, I'd like to start by using MySQL. The question is, is it possible to structure data and queries in such a way that it would be fairly easy to later port it to Cassandra? Main idea, I guess, would be writing MySQL queries that would be possible to change to same Cassandra queries. Maybe you have a better suggestion?

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  • What's the best way to refactor this Rails controller?

    - by Robert DiNicolas
    I'd like some advice on how to best refactor this controller. The controller builds a page of zones and modules. Page has_many zones, zone has_many modules. So zones are just a cluster of modules wrapped in a container. The problem I'm having is that some modules may have some specific queries that I don't want executed on every page, so I've had to add conditions. The conditions just test if the module is on the page, if it is the query is executed. One of the problems with this is if I add a hundred special module queries, the controller has to iterate through each one. I think I would like to see these module condition moved out of the controller as well as all the additional custom actions. I can keep everything in this one controller, but I plan to have many apps using this controller so it could get messy. class PagesController < ApplicationController # GET /pages/1 # GET /pages/1.xml # Show is the main page rendering action, page routes are aliased in routes.rb def show #-+-+-+-+-Core Page Queries-+-+-+-+- @page = Page.find(params[:id]) @zones = @page.zones.find(:all, :order => 'zones.list_order ASC') @mods = @page.mods.find(:all) @columns = Page.columns # restful params to influence page rendering, see routes.rb @fragment = params[:fragment] # render single module @cluster = params[:cluster] # render single zone @head = params[:head] # render html, body and head #-+-+-+-+-Page Level Json Conversions-+-+-+-+- @metas = @page.metas ? ActiveSupport::JSON.decode(@page.metas) : nil @javascripts = @page.javascripts ? ActiveSupport::JSON.decode(@page.javascripts) : nil #-+-+-+-+-Module Specific Queries-+-+-+-+- # would like to refactor this process @mods.each do |mod| # Reps Module Custom Queries if mod.name == "reps" @reps = User.find(:all, :joins => :roles, :conditions => { :roles => { :name => 'rep' } }) end # Listing-poc Module Custom Queries if mod.name == "listing-poc" limit = params[:limit].to_i < 1 ? 10 : params[:limit] PropertyEntry.update_from_listing(mod.service_url) @properties = PropertyEntry.all(:limit => limit, :order => "city desc") end # Talents-index Module Custom Queries if mod.name == "talents-index" @talent = params[:type] @reps = User.find(:all, :joins => :talents, :conditions => { :talents => { :name => @talent } }) end end respond_to do |format| format.html # show.html.erb format.xml { render :xml => @page.to_xml( :include => { :zones => { :include => :mods } } ) } format.json { render :json => @page.to_json } format.css # show.css.erb, CSS dependency manager template end end # for property listing ajax request def update_properties limit = params[:limit].to_i < 1 ? 10 : params[:limit] offset = params[:offset] @properties = PropertyEntry.all(:limit => limit, :offset => offset, :order => "city desc") #render :nothing => true end end So imagine a site with a hundred modules and scores of additional controller actions. I think most would agree that it would be much cleaner if I could move that code out and refactor it to behave more like a configuration.

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  • What exactly is Arel in Rails 3.0?

    - by Will
    I understand that it is a replacement for ActiveRecord and that it uses objects instead of queries. But... why is this better? will objects/queries be "easier" to create? will it lead to more efficient SQL queries? will it be compatible with all major DB's? - I assume it will. will it be easier/harder to use with stored procedures?

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  • How do I request a single random row from a force.com database in SOQL?

    - by Ollie C
    Total row-count is in the range 10k-100k rows. Can I use RAND() on force.com? Unfortunately although all the rows have a unique numeric identifier, there are many gaps, and I'd often want to select a random row from a filtered subset anyway. I suspect there's no particularly efficient way to do this, but is it possible at all? Ultimately all I want to do is to extract one row from a table (or a subset based on specific filter criteria) at random. If force.com doesn't let me select a random row, then can I query the rows to select from, and assign sequential IDs to all the rows, say 1-1,035, and then select a random number in that range locally, say 349, and then get row 349?

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  • How to secure the communication between an MSSQL database and a c# administrative tool?

    - by citronas
    How can I secure the communication between a C# programm running locally on my computer and a MSSQL Server in a hosted environment? I have an asp.net application that is secured by SSL encryption. So using the asp.net from an open wlan connection is no problem. How can I achieve the same kind of encryption for my administrative tool? Would it be best to write a service? But how would that connection to the service be secured?

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  • A good approach to db planing for reporting service

    - by Itay Moav
    The scenario: Big system (~200 tables). 60,000 users. Complex reports that will require me to do multiple queries for each report and even those will be complex queries with inner queries all over the place + some processing in PHP. I have seen an approach, which I am not sure about: Having one centralized, de-normalized, table that registers any activity in the system which is reportable. This table will hold mostly foreign keys, so she should be fairly compact and fast. So, for example (My system is a virtual learning management system), A user enrolls to course, the table stores the user id, date, course id, organization id, activity type (enrollment). Of course I also store this data in a normalized DB, which the actual application uses. Pros I see: easy, maintainable queries and code to process data and fast retrieval. Cons: there is a danger of the de-normalized table to be out of sync with the real DB. Is this approach worth considering, or (preferably from experience) is total $#%#%t?

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  • HTML stops at a PHP script made to connect to a mysql database. No errors printed.

    - by DavidR
    I'm trying to set up a login script for PHP using the tutorial on this site. The problem is that the site stops when it hits these lines, no error, no text: <?php $conn = mysql_connect('localhost', 'root', 'password') or die('error line7' . mysql_error()); mysql_select_db('mydb', $conn) or die('error line8' . mysql_error()); ?> If I take out these lines, the rest of the html runs perfectly. I've double checked my passwords and everything, nothing is working. I know very little about php and mysql other than what I've learned trying to set this up.

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