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  • Entity framework and database logic.

    - by Xavier Devian
    Hi all, i have a question that's being around for several years. As all you know entity framework is an ORM tool that tries to model the database to an object oriented access model. All the samples I've seen are quering directly to the database tables. So, which is the role of the views in the database now?. The views were used to model the database in a more friendly way, that is, several physical tables, one logic table. This was great for example in hidding the complex relational model on stored procedures as queryng the views inside them was much easier than reproducing the query joins over and over on each stored procedure. So the question is, why is entity framework so good if stored procedures can not take benefit of it?

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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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  • 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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  • 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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  • 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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  • Visual Studio 2008 (C#) with SQL Compact Edition database error: 26

    - by Tommy
    A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) I've created a SQL compact database, included it in my application, and can connect to the database fine from other database editors, but within my application im trying using (SqlConnection con = new SqlConnection(Properties.Settings.Default.DatabaseConnection)) { con.Open(); } the connection string is Data Source=|DataDirectory|\Database.sdf I'm stumped, any insight?

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  • Composite Primary and Cardinality

    - by srini.venigalla
    I have some questions on Composite Primary Keys and the cardinality of the columns. I searched the web, but did not find any definitive answer, so I am trying again. The questions are: Context: Large (50M - 500M rows) OLAP Prep tables, not NOSQL, not Columnar. MySQL and DB2 1) Does the order of keys in a PK matter? 2) If the cardinality of the columns varies heavily, which should be used first. For example, if I have CLIENT/CAMPAIGN/PROGRAM where CLIENT is highly cardinal, CAMPAIGN is moderate, PROGRAM is almost like a bitmap index, what order is the best? 3) What order is the best for Join, if there is a Where clause and when there is no Where Clause (for views) 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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  • 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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  • Using a CMS with an external database

    - by George Reith
    I am looking at building an external site with a CMS, probably Drupal or ExpressionEngine. The problem is that our company already has a membership database that is designed to work with our existing enterprise software. Migrating data from the database manually is not an option as modifications and new data must be accessible in real-time. Because the design of the external database will differ from the CMS's own I have decided the best way forward is to use two databases and force the CMS to use the external to read user information (cannot write to) and a local for everything else the CMS needs to do (read + write). Is this feasible with these Drupal or ExpressionEngine? Ideally I need to be able to use hooks as I do not wan't to modify core CMS files. Sifting through the docs I am not able to find what I would hook into for ether CMS. (Note: I know it is possible, but I want to know if it's feasible). Finally if there is a better way of handling this situation please also chime in. Perhaps there is something at the database level to reference a field or table in an external database? I'm clutching at straws someone can point me in the right direction I'm sure.

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  • how to tackle a custom forms database

    - by Neil Hickman
    I'm currently researching a project for the place that I work in. We are trying to create a system that will allow forms to be set up dynamically from a database. My question is what database structure would best suit something like this? I currently have a structure of: forms_form forms_formfields forms_formdata I don't think this is the most appropriate layout for this. Basically to make is make sense I need to be able to make a form within the database that can have infinite fields all customized and have the data when submitted stored in the database.

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  • Database schema for simple stats project

    - by Bubnoff
    Backdrop: I have a file hierarchy of cvs files for multiple locations named by dates they cover ...by month specifically. Each cvs file in the folder is named after the location. eg', folder name: 2010-feb contains: location1.csv location2.csv Each CSV file holds records like this: 2010-06-28, 20:30:00 , 0 2010-06-29, 08:30:00 , 0 2010-06-29, 09:30:00 , 0 2010-06-29, 10:30:00 , 0 2010-06-29, 11:30:00 , 0 meaning of record columns ( column names ): Date, time, # of sessions I have a perl script that pulls the data from this mess and originally I was going to store it as json files, but am thinking a database might be more appropriate long term ...comparing year to year trends ...fun stuff like that. Pt 2 - My question/problem: So I now have a REST service that coughs up json with a test database. My question is [ I suck at db design ], how best to design a database backend for this? I am thinking the following tables would suffice and keep it simple: Location: (PK)location_code, name session: (PK)id, (FK)location_code, month, hour, num_sessions I need to be able to average sessions (plus min and max) for each hour across days of week in addition to days of week in a given month or months. I've been using perl hashes to do this and am trying to decide how best to implement this with a database. Do you think stored procedures should be used? As to the database, depending on info gathered here, it will be postgresql or sqlite. If there is no compelling reason for postgresql I'll stick with sqlite. How and where should I compare the data to hours of operation. I am storing the hours of operation in a yaml file. I currently 'match' the hour in the data to a hash from the yaml to do this. Would a database open simpler methods? I am thinking I would do this comparison as I do now then insert the data. Can be recalled with: SELECT hour, num_sessions FROM session WHERE location_code=LOC1 Since only hours of operation are present, I do not need to worry about it. Should I calculate all results as I do now then store as a stats table for different 'reports'? This, rather than processing on demand? How would this look? Anyway ...I ramble. Thanks for reading! Bubnoff

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  • How to store values in database C# ?

    - by hello-all
    Hello all, I have a form that has text boxes, buttons on it for the user to sign up and sign in. I need to store the entered sign up credentials in any database(Oracle, Service based database, local database). Then when he tries to sign in, entered credentials should be compared with stored sign up values for authentication. This is done in visual studio, c#. Can anyone please give me hints or any references? Thank you

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  • Visual Studio 2008 patching without suppressing database

    - by John
    Hi, I made a program using visual c# which connects to a local .mdf sql database. I've published it using the Publish Wizard, used the files on another computer to install it and it worked fine. However, some bugs were discovered. I've corrected the problems, published it again and tried to patch the program on the 2nd computer. After much trials and errors, fastest way to patch is to overwrite the .application file. Suprisingly, the database was also overwritten. Question is: How do I make new version of the program and install it on the other computer without modifying the database? On developping computer, database appears as a .mdf file which can be copied, but on 2nd computer this file does not exists. Supplementary info: -Developping computer: Vista, using Visual Studio 2008 with Server 2005 -2nd computer: XP using microsoft express server 2005

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  • Performance impact of not implementing relationships at the database level?

    - by JVerstry
    Let's imagine a data model with customers and invoices. There is a 1 to n relationship between a customer and its invoices. We uses an ORM (like Hibernate). One can explicitely implement the 1-n relationship (using JPA for example) or not. If not, then one must do a bit more work to fetch invoices. However, it is much easier to maintain, improve and develop the data model of applications where relationships between objects are not explicitely implemented in the database. My question is, has anyone noticed a significant performance impact when not implementing the relationships in the database?

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  • Lightest Database to be packed with an application

    - by Yatendra Goel
    I am developing a Java Desktop Application and want a light database that can be used with Hibernate and that can be packed with an application. I was going to use Derby database. It's size is near 2 MB. But before that I wanted to have views of experts on SO. Will it work with Hibernate? Actually, I am new to Hibernate and was studying that it requires a Dialect for a database so Is Hibernate has dialect for Derby?

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  • Start developing a database application using Oracle + Net Beans

    - by Ranhiru
    I have thought of creating my first database application for one of my projects using Oracle and Java. I have chosen Netbeans as my development environment. I have a few questions to getting started. Please bare with me as I'm a complete beginner to Oracle + Netbeans This will be a data intensive (yet still for a college project) database application. I do not need 1000 user concurrency or any other very advanced features but basic stuff such as triggers, stored procedures etc. Will the 11g "Express" (XE) suffice for my requirements? Do i need any Java to Oracle bridge (database connectivity driver eg. ODBC etc) for Netbeans to connect to the oracle database? If yes, what are they? Does Netbeans support Oracle databases natively? Any easy to follow guide on how do i connect to the database and insert/retrieve/display data on a J2SE application? (I know that i should Google this but if there's any guide previously followed by anyone and is considered easy, it would be greatly appreciated.)

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  • Retrieve data from database

    - by martin
    I need to use C# to get data from database(sql) and the data in database is updated every few seconds. So do I have to make a loop or there is a better way to do that? Is it possible that when database is updating, the program can wait until it finishes updating? thx!

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  • Best way to model Customer <--> Address

    - by Jen
    Every Customer has a physical address and an optional mailing address. What is your preferred way to model this? Option 1. Customer has foreign key to Address Customer (id, phys_address_id, mail_address_id) Address (id, street, city, etc.) Option 2. Customer has one-to-many relationship to Address, which contains a field to describe the address type Customer (id) Address (id, customer_id, address_type, street, city, etc.) Option 3. Address information is de-normalized and stored in Customer Customer (id, phys_street, phys_city, etc. mail_street, mail_city, etc.) One of my overriding goals is to simplify the object-relational mappings, so I'm leaning towards the first approach. What are your thoughts?

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  • Moving dozens of existing standalone retail sites to one central inventory database: what should I know going in?

    - by palintropos
    This will be the first project of this scale that I have attempted, and the first time I have run a website at all (much less dozens) using an off-site database. In particular, I'd like to know: what sort of optimizations I should read up on to make this run as smoothly as possible? any pitfalls/gotchas wiser, more experienced folk are aware of I should be on the lookout for, and what damage-control and preventative measures I should take against the nightmare scenario of the main server (hosting the database) having an outage, grinding over 100 websites to a halt (because they have no access to the product data).

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  • Data Warehouse: Modelling a future schedule

    - by Pat
    I'm creating a DW that will contain data on financial securities such as bonds and loans. These securities are associated with payment schedules. For example, a bond could pay quarterly, while a mortage would usually pay monthly (sometimes biweekly). The payment schedule is created when the security is traded and, in the majority of cases, will remain unchanged. However, the design would need to accomodate those cases where it does change. I'm currently attempting to model this data and I'm having difficulty coming up with a workable design. One of the most commonly queried fields is "next payment date". Users often want to know when a security will pay next. Therefore, I want to make it as easy as possible for them to get the next payment date and amount for each security. Also, users often run historical queries in which case they'd want the next payment date and amount as of a specific point in time. For example, they may want to look back at 1/31/09 and query the next payment dates (which would usually be in February 2009 for mortgages). It's also common that they want to query a security's entire payment schedule, which might consist of 360 records (30 year mortgage x 12 payments/year). Since the next payment date and amount would be changing each month or even biweekly, these fields wouldn't seem to fit into a slow-changing dimension very well. It would probably make more sense to use a fact table, but I'm unsure of how to model it. Any ideas would be greatly appreciated.

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  • Database Schema Validation - deployable/compilable

    - by boomhauer
    Looking for a tool that will allow building database schema validation that can be compiled into a standalong tool or as a module to be used in another application. The scenario is - a client/server application that is sold to customers, and maintained through service releases. The service releases include database scripts to updated the database with any schema changes etc. However, since this is a database and the customer could either run upgrade scripts incorrectly, or tinker around and mess up something in the DB I would like to have this tool available with each release so we can verify the struture, and possibly some data, is valid. Also to have it available for remote debugging when a customer has a service ticket. Schema compare tools I've researched work great for comparing local databases, but I haven't seen something that can generate something that is deployable with our application. Thanks!

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  • Database class is not correctly connecting to my database.

    - by blerh
    I'm just venturing into the world of OOP so forgive me if this is a n00bish question. This is what I have on index.php: $dbObj = new Database(); $rsObj = new RS($dbObj); This is the Database class: class Database { private $dbHost; private $dbUser; private $dbPasswd; private $dbName; private $sqlCount; function __construct() { $this->dbHost = 'localhost'; $this->dbUser = 'root'; $this->dbPasswd = ''; $this->dbName = 'whatever'; $this->sqlCount = 0; } function connect() { $this->link = mysql_connect($this->db_host, $this->db_user, $this->db_passwd); if(!$this->link) $this->error(mysql_error()); $this->selection = mysql_select_db($this->db_name, $this->link); if(!$this->selection) $this->error(mysql_error()); } } I've shortened it to just the connect() method to simplify things. This is the RS class: class RS { private $username; private $password; function __construct($dbObj) { // We need to get an account from the db $dbObj->connect(); } } As you can probably see, I need to access and use the database class in my RS class. But I get this error when I load the page: Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'ODBC'@'localhost' (using password: NO) in C:\xampp\htdocs\includes\database.class.php on line 22 The thing is I have NO idea where it got the idea that it needs to use ODBC as a user... I've read up on doing this stuff and from what I can gather I am doing it correctly. Could anyone lend me a hand? Thank you.

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