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  • Compare Database container and class container

    - by Mohit Deshpande
    I am using a SQL Server database in my current project. I was watching the MVC Storefront videos (specifically the repository pattern) and I noticed that Rob (the creator of MVC Storefront) used a class called Category and Product, instead of a database and I have notice that using LINQ-SQL or ADO.NET, that a class is generated. Is there an advantage to using a class over a database to store information? Or is it the other way around? Or are they even comparable?

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  • Delete ONE SPECIFIC table of a database - leave the rest intact

    - by Jayomat
    Hi, I have a database where I store two different kinds of data. One table is for favorite routes, the other stores the retrieved routes from a server. I can retrieve the routes etc just fine. But after retrieving the first Route, pressing back or HOME, and then retrieving another route, the routes table is filled with all the old routes plus the new ones. So my question: how do I delete ONLY the routes table and not the whole database because I don't want to delete the added favorites....?! I found the following function in the android docs: public int delete (String table, String whereClause, String[] whereArgs) and I tried to implement it, but I must pass a SQLiteDataBase as an argument. But how? I implemented: public void deleteTableRoutes(SQLiteDataBase db){ db.delete("routes", null, null); } But I want to call this function from a different class where I have no reference to the database.. so what do I have to pass as an argument? Or how do I get a reference to my database? I build my database upon the code example of the NotePadExample from the dev docs. How to solve this problem? thanks

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  • Automatic database generation / migration with perl

    - by pistacchio
    Hi, In Ror or Django or web2py you can "describe" a database (as a set of classes that remaps to tables) and the framework (having being provided with a connection string to the desired database) generates the tables, fields, relations and in the case of RoR and web2py it also keeps it up-to-date (eg, removing a class drops the table, adding a property to the class triggers an "alter table add" etc). Is there any perl module that does the same? Eg, it takes the YAML / XML / JSON description of a database as input and modifies / generates the database accordingly? Thanks in advance.

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  • Why implement DB connection pointer object as a reference counting pointer? (C++)

    - by DVK
    At our company one of the core C++ classes (Database connection pointer) is implemented as a reference counting pointer. To be clear, the objects are NOT DB connections themselves, but pointers to a DB connection object. The library is very old, and nobody who designed is around anymore. So far, nether I, nor any C++ experts in the company that I asked have come up with a good reason for why this particular design was chosen. Any ideas? It is introducing some problems (partially due to awful reference pointer implementation used), and I'm trying to understand if this design actually has some deep underlying reasons? The usage pattern these days seems to be that the DB connection pointer object is returned by a DB connection manager class, and it's somewhat unclear whether DB connection pointers were designed to be able to be used independently of DB connection manager.

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  • How do you handle objects that need custom behavior, and need to exist as an entity in the database?

    - by Scott Whitlock
    For a simple example, assume your application sends out notifications to users when various events happen. So in the database I might have the following tables: TABLE Event EventId uniqueidentifier EventName varchar TABLE User UserId uniqueidentifier Name varchar TABLE EventSubscription EventUserId EventId UserId The events themselves are generated by the program. So there are hard-coded points in the application where an event instance is generated, and it needs to notify all the subscribed users. So, the application itself doesn't edit the Event table, except during initial installation, and during an update where a new Event might be created. At some point, when an event is generated, the application needs to lookup the Event and get a list of Users. What's the best way to link the event in the source code to the event in the database? Option 1: Store the EventName in the program as a fixed constant, and look it up by name. Option 2: Store the EventId in the program as a static Guid, and look it up by ID. Extra Credit In other similar circumstances I may want to include custom behavior with the event type. That is, I'll want subclasses of my Event entity class with different behaviors, and when I lookup an event, I want it to return an instance of my subclass. For instance: class Event { public Guid Id { get; } public Guid EventName { get; } public ReadOnlyCollection<EventSubscription> EventSubscriptions { get; } public void NotifySubscribers() { foreach(var eventSubscription in EventSubscriptions) { eventSubscription.Notify(); } this.OnSubscribersNotified(); } public virtual void OnSubscribersNotified() {} } class WakingEvent : Event { private readonly IWaker waker; public WakingEvent(IWaker waker) { if(waker == null) throw new ArgumentNullException("waker"); this.waker = waker; } public override void OnSubscribersNotified() { this.waker.Wake(); base.OnSubscribersNotified(); } } So, that means I need to map WakingEvent to whatever key I'm using to look it up in the database. Let's say that's the EventId. Where do I store this relationship? Does it go in the event repository class? Should the WakingEvent know declare its own ID in a static member or method? ...and then, is this all backwards? If all events have a subclass, then instead of retrieving events by ID, should I be asking my repository for the WakingEvent like this: public T GetEvent<T>() where T : Event { ... // what goes here? ... } I can't be the first one to tackle this. What's the best practice?

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  • Syncing magento database froms development to production

    - by ringerce
    I use git for version control. I have a development, staging and production environment. When I finish in development I push to staging for review by the client. When approved, I push changes from staging to production. That works fine as long as there is no database changes. What happens if I install modules via Magento connect on local development and it makes database modifications. How would I push those changes up to the production server since the production server is always changing? Edit: I wrote two shell scripts. One that pulls the production database down to my development server, replaces base url with develpment url and updates my development db accordingly. It also leaves the production sql dump behind to be added to my git repo. I'm not really sure if it's beneficial to keep the raw dumps in source control but I'm going to try it out. The second scripts moves the development database up to staging and essentially performs the same operations as the first. Now when it comes time to move to production I pull the updated production repo into the production server and allow magento to do it's thing. I also started using SQLYog recently and it has a database comparison wizard which will give me the differences in my development and production databases and allow me to merge the changes in selectively. It always creates a migration script that I added to source control as well. If anything goes wrong I can run the comparison to see if anything was missed. Does this sounds like a decent workflow to you guys?

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  • How to distribute a unique database already in production?

    - by JVerstry
    Let's assume a successful web spring application running on a MySql or PostGre kind of database. The traffic is becoming so high and the amount of data is becoming so big that a distributed dataase solution needs to be implemented. It is a scalability issue. Let's assume this application is using Hibernate and the data access layer is cleanly separated with DAO objects. What would be the best strategy to scale this database? Does anyone have hands on experience to share? Is it possible to minimize sharding code (Shard) in the application? Ideally, one should be able to add or remove databases easily. A failback solution is welcome too. I am not looking for you could go for sharding or you could go no sql kind of answers. I am looking for deeper answers from people with experience.

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  • Plan variable and call dependencies

    - by Gerenuk
    I'd like to write down the design of my program to understand the dependencies and calls better. I know there are class diagrams which show inheritance and attribute variables. However I'd also like to document the input parameters to method functions and in particular which calls the methods function executes inside (e.g. on the input parameters). Also sometimes it might be useful to show how actual objects are connected (if there is a standard structure). This way I can have a better understanding of the modules and design before starting to program. Can you suggest a method to do this software design? It should be one-to-one to programming code structure so that I really notice all quirks beforehand (instead of high-level design where thing are hard to implement without further work). Maybe some special diagram or tool or a combination? It is static dependency and call design rather than time dependent execution monitoring. (I use Python if you have any specialized recommendations).

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  • Database schemas WAY out of sync - need to get up to date without losing data

    - by Zind
    The problem: we have one application that has a portion which is used by a very small subset of the total users, and that part of the application is running off of a separate database as well. In a perfect world, the schemas of the two databases would be synced up, but such is not the case. Some migrations have been run on the smaller database, most haven't; and furthermore, there is nothing such as revision number to be able to easily identify which have and which haven't. We would like to solve this quandary for future projects. During a discussion we've come up with the following possible plan of action, and I am wondering if anyone knows of any project which has already solved this problem: What we would like to do is create an empty database from the schema of the large fully-migrated database, and then move all of the data from the smaller non-migrated database into that empty one. If it makes things easier, it can probably be assumed for the sake of this problem specifically that no migrations have ever removed anything, only added. Else, if there are other known solutions, I'd like to hear them as well.

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  • Database Change Auditing - Part of or Abstracted from ORM / Application Layer?

    - by BrandonV
    My fellow developers and I are at a crossroads in how to go about continuing our auditing of database changes. Most of our applications log changes via INSERT, UPDATE, and DELETE triggers. A few of our newer applications audit at the ORM layer; specifically using Hibernate Envers. While ORM layer auditing provides a much cleaner interface and is much more maintainable, it will not capture any manual database changes that are made. ORM layer auditing also means that our libraries will currently require a dependency on our ORM implementation unless, specifically in our case for example, JPA plans on providing something in the near future. Is there a common paradigm that addresses this?

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  • How can I give my client "full access" to their PHP application's MySQL database?

    - by Micah Delane Bolen
    I am building a PHP application for a client and I'm seriously considering WordPress or a simple framework that will allow me to quickly build out features like forums, etc. However, the client is adamant about having "full access" to the database and the ability to "mine the data." Unfortunately, I'm almost certain they will be disappointed when they realize they won't be able to easily glean meaningful insight by looking at serialized fields in wp_usermeta, etc. One thought I had was to replicate a variation on the live database where I flatten out all of those ambiguous and/or serialized fields into something that is then parsable by a mere mortal using a tool as simple as phpMyAdmin. Unfortunately, the client is not going to settle for a simple backend dashboard where I create the custom reports for them even though I know that would be the easiest and most sane approach.

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  • Good way to make changes to production database / source code

    - by This is it
    Hi I'm interested to find out what would be the good way to make changes to production database and source code in web application (ASP.NET, SQL Server 2008). A little bit more details, we develop on local machines, and then we need to transfer the code and database changes to production (pretty much standard story). At the moment we do it in the evening, change the database directly from management studio on production server, and then just overwrite the existing asp.net code (copy/past). Thanks

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  • Can I create my own database from PHP?

    - by Roman
    I have a working PHP server. Now I want to use databases (MySQL or something similar). Is it possible to create a database from PHP? I would like to emphasize that in my case I do not have any user-name and password to which I can use to connect to MySQL server. I also do not have a control-panel where I could create a database or a table in an existing database.

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  • How do I create and link to a database in ASP.NET (Razor) with Visual studio 2013?

    - by Blake
    We have a simple web app, part of which allows users to create accounts and then, hopefully soon, to write blog posts. The user log in system is working great, it utilizes the given .sdf database created when a new project is created. We would like to expand it now to allow for blog data (the title, body of the blog, image posts perhaps, etc). However, I'm unsure of how to add another table to the user database for this purpose - or if that would even be best since it has sensitive information in it. I've been reading blog post after blog post and still can't find anything current on this. All of the articles are for MVC projects or older versions of VS. If someone could point me in the right direction it would be greatly appreciated!

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  • Google App Engine Database Index

    - by fjsj
    I need to store a undirected graph in a Google App Engine database. For optimization purposes, I am thinking to use database indexes. Using Google App Engine, is there any way to define the columns of a database table to create its index? I will need some optimization, since my app uses this stored undirected graph on a content-based filtering for item recommendation. Also, the recommender algorithm updates the weights of some graph's edges. If it is not possible to use database indexes, please suggest another method to reduce query time for the graph table. I believe my algorithm does more data retrieval operations from graph table than write operations. PS: I am using Python.

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  • how to make a software and preserve database integrity and correctness and please help confused

    - by user287745
    i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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  • Oracle Unveils Breakthrough Technology: Database In-Memory

    - by Mala Narasimharajan
    Missed Larry Ellison's big announcement this morning? Today, Oracle announced . Oracle Database In-Memory.  Oracle Database In-Memory  transparently extends the power of Oracle Database 12c to enable organizations to discover business insights in real-time while simultaneously increasing transactional performance. Here's why you should care - this new breakthrough technology enables enterprises to get faster answers to business questions ultimately leading to faster business action. Oracle Database In-Memory delivers leading-edge in-memory performance without the need to restrict functionality or accept compromises, complexity and risk. Deploying Oracle Database In-Memory with virtually any existing Oracle Database-compatible application is as easy as flipping a switch--no application changes are required.  For more information on Oracle Database In-Memory go to http://www.oracle.com/us/corporate/press/2215795

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  • Embed a database in the .apk of a distributed application [Android]

    - by Sephy
    Hi everybody, My question is I think quite simple but I don't think the answer will be... I have quite a lot of content to have in my application to make it run properly, and I'm thinking of putting all of it in a database, and distribute it in an embeded database with the application in the market. The only trouble is that I have no idea of how to do that. I know that I can extract a file .db from Eclipse DDMS with the content of my database, and I suppose I need to put it in the asset folder of my application, but then how to make the application use it to regenerate the application database? If you have any link to some code or help, that would be great. Thanks

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  • Immutable design with an ORM: How are sessions managed?

    - by Programmin Tool
    If I were to make a site with a mutable language like C# and use NHibernate, I would normally approach sessions with the idea of making them as create only when needed and dispose at request end. This has helped with keeping a session for multiple transactions by a user but keep it from staying open too long where the state might be corrupted. In an immutable system, like F#, I would think I shouldn't do this because it supposes that a single session could be updated constantly by any number of inserts/updates/deletes/ect... I'm not against the "using" solution since I would think that connecting pooling will help cut down on the cost of connecting every time, but I don't know if all database systems do connection pooling. It just seems like there should be a better way that doesn't compromise the immutability goal. Should I just do a simple "using" block per transaction or is there a better pattern for this?

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  • How can I sync a database driven website to a different server

    - by tbrandao
    I have a website using cPanel on a dedicated account, I would like to be able to automatically sync the website to a second hosting company or perhaps to a local (in house ) server. Basically this is a type of replication. The website is database driven (MySQL), so Ideally it would sync everything (content, database, emails etc.) , but most importantly is syncing the website files and its database. I'm not so much looking for a fail-over solution as an automatic replication solution, so if the primary site (Server) goes off-line, I can manually bring up the replicated site quickly. I'm familiar with tools like unison and rsync, but most of these only sync file(s) and do not do too well with open database connections.

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  • Windows Mobile local database

    - by ThePower
    Hi, I'm writing an application for windows mobile 6 and above that requires a local database. I was wondering if anyone has any experience with database hosting on windows mobile and which database management system would be most suitable for development. Thanks in advance, Lloyd

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  • Android database closed exception

    - by Bombastic
    I'm working on a project where I'm downloading and saving data from web to sqlite database. A few minutes ago I receive a strange exception to our server from a user which is saying that the sqlite database is already closed..and I just checked the whole file where the exception happened and I'm not calling dbHelper.close();. Here is the function where the app crashes and LogCat message : public void insertCollectionCountries(JSONObject obj, Context context) { //Insert in collection_countries if(RPCCommunicator.isServiceRunning){ Log.w("","JsonCollection - insertCollectionCountries"); ContentValues valuesCountries = new ContentValues(); try { collectionId = Integer.parseInt(obj.getString("collection_id")); dbHelper.deleteSQL("collection_countries", "collection_id=?", new String[] {Integer.toString(collectionId)}); JSONArray arrayCountries = obj.getJSONArray("country_availability"); for (int i=0; i<arrayCountries.length(); i++) { valuesCountries.put("collection_id", collectionId); String countryCode = arrayCountries.getString(i); valuesCountries.put("country_code", countryCode); dbHelper.executeQuery("collection_countries", valuesCountries); } } catch (JSONException e){ e.printStackTrace(); } } } and the error is on that line : dbHelper.executeQuery("collection_countries", valuesCountries); here is the LogCat message : java.lang.IllegalStateException: database /data/data/com.stampii.stampii/databases/stampii_sys_tpl.sqlite (conn# 0) already closed at android.database.sqlite.SQLiteDatabase.verifyDbIsOpen(SQLiteDatabase.java:2123) at android.database.sqlite.SQLiteDatabase.setTransactionSuccessful(SQLiteDatabase.java:734) at com.stampii.stampii.comm.rpc.SystemDatabaseHelper.execQuery(SystemDatabaseHelper.java:298) at com.stampii.stampii.comm.rpc.SystemDatabaseHelper.executeQuery(SystemDatabaseHelper.java:291) at com.stampii.stampii.jsonAPI.JsonCollection.insertCollectionCounries(JsonCollection.java:548) at com.stampii.stampii.jsonAPI.JsonCollection.executeInsert(JsonCollection.java:181) at com.stampii.stampii.collections.MyService.downloadCollections(MyService.java:122) at com.stampii.stampii.collections.MyService$2.run(MyService.java:74) at java.lang.Thread.run(Thread.java:1020) and function in my dbHelperClass which I'm using to insert data : public boolean executeQuery(String tableName,ContentValues values){ return execQuery(tableName,values); } private boolean execQuery(String tableName,ContentValues values){ sqliteDb = instance.getWritableDatabase(); sqliteDb.beginTransaction(); sqliteDb.insert(tableName, null, values); sqliteDb.setTransactionSuccessful(); sqliteDb.endTransaction(); return true; } Any ideas which can close my sqlite database or what can cause that exception, because I've tested this code on a few emulators with different Android versions, different devices (HTC EVO 3D, Samsung Galaxy Nexus,HTC Desire, LG OPTIMUS PAD, Samsung Galaxy S2, Samsung Galaxy Note) and it's working fine. Thanks in advance!

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  • What database strategy to choose for a large web application

    - by Snoopy
    I have to rewrite a large database application, running on 32 servers. The hardware is up to date, each machine has two quad core Xeon and 32 GByte RAM. The database is multi-tenant, each customer has his own file, around 5 to 10 GByte each. I run around 50 databases on this hardware. The app is open to the web, so I have no control on the load. There are no really complex queries, so SQL is not required if there is a better solution. The databases get updated via FTP every day at midnight. The database is read-only. C# is my favourite language and I want to use ASP.NET MVC. I thought about the following options: Use two big SQL servers running SQL Server 2012 to serve the 32 servers with data. On the 32 servers running IIS hosting providing REST services. Denormalize the database and use Redis on each webserver. Use booksleeve as a Redis client. Use a combination of SQL Server and Redis Use SQL Server 2012 together with Hadoop Use Hadoop without SQL Server What is the best way for a read-only database, to get the best performance without loosing maintainability? Does Map-Reduce make sense at all in such a scenario? The reason for the rewrite is, the old app written in C++ with ISAM technology is too slow, the interfaces are old fashioned and not nice to use from an website, especially when using ajax. The app uses a relational datamodel with many tables, but it is possible to write one accerlerator table where all queries can be performed on, and all other information from the other tables are possible by a simple key lookup.

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