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  • .NET Database Apps: Your Preferred Setup

    - by mdvaldosta
    I'm struggling to settle into a pattern for developing typical database driven apps in C# and Visual Studio. There are so many ways to set them up, using drag/drop datasets and adapters or writing the queries manually in ADO.NET or Linq to SQL, Linq to Entities, to bind or not to data bind etc etc. Where to store the connection string, in app.config or in a method or both etc etc. So many tutorials and all of them are different. Everytime I write something I start hating the way it looks and works, so I scrap it and start over. It's getting a bit tedious. Maybe it's alittle of the OCD in me. Would any of you professional developers out there share your method of setting up and structuring your database logic and maybe some sample code? It's really how to go about organizing the code and the method(s) of interacting with SQL that I'm trying to get into a routine with, one that works and won't get me laughed at by someone reviewing it.

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  • Is SQL used by PDO database independent?

    - by Pheter
    Different databases have slight variations in their implementations of SQL. Does PDO handle this? If I write an SQL query that I use with PDO to access a MySQL database, and later tell PDO to start using a different type of database, will the query stop working? Or will PDO 'convert' the query so that it continues to work? If PDO does not do this, are there any PHP libraries that allow me to write SQL according to a particular syntax, and then the library will handle converting the SQL so that it will run on different databases?

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  • 'e-Commerce' scalable database model

    - by Ruben Trancoso
    I would like to understand database scalability so I've just heard a talk about Habits of Highly Scalable Web Applications http://techportal.ibuildings.com/2010/03/02/habits-of-highly-scalable-web-applications/ On it, the presenter mainly talk about relational database scalability. I also have read something about MapReduce and Column oriented tables, big tables, hypertable etc... trying to understand which are the most up to date methods to scale web application data. But the second group, to me, is being hard to understand where it fits. It serves as transactional, reliable data store? or not, its just for large access and processing and to handle fine graned operations we will ever need to rely on RDBMSs? Could someone give a comprehensive landscape for those new technologies and how to use it?

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  • Rolling back database changes

    - by justin
    Hi, I work in team which uses Work flow management tool. I was presented with a challenge where the user should be able to roll back the changes made anytime during the flow to a certain point in the past. Surely the toll can handle it but the additional database calls that may have made during these activities have to be manually rolled back. the challenge is that there are multiple parallel paths and there different permutations of external database calls. So is there a frame work or a way to keep track of these DB calls and rollback them?. thank you, Justin

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  • C# programatically using a string as object name when instantiating an object

    - by emk
    This is a contrived example, but lets say I have declared objects: CustomObj fooObj; CustomObj barObj; CustomObj bazObj; And I have an string array: string[] stringarray = new string[] {"foo","bar","baz"}; How can I programatically access and instantiate those objects using the string array, iterating using something like a foreach: foreach (string i in stringarray) { `i`Obj = new CustomObj(i); } Hope the idea I'm trying to get across is clear. Is this possible in C#? Thanks in advance.

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  • Recommendations for an in memory database vs thread safe data structures

    - by yx
    TLDR: What are the pros/cons of using an in-memory database vs locks and concurrent data structures? I am currently working on an application that has many (possibly remote) displays that collect live data from multiple data sources and renders them on screen in real time. One of the other developers have suggested the use of an in memory database instead of doing it the standard way our other systems behaves, which is to use concurrent hashmaps, queues, arrays, and other objects to store the graphical objects and handling them safely with locks if necessary. His argument is that the DB will lessen the need to worry about concurrency since it will handle read/write locks automatically, and also the DB will offer an easier way to structure the data into as many tables as we need instead of having create hashmaps of hashmaps of lists, etc and keeping track of it all. I do not have much DB experience myself so I am asking fellow SO users what experiences they have had and what are the pros & cons of inserting the DB into the system?

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  • ASP .net Dropdown list not saving the selected value to database

    - by user326010
    Hi In the following code i want to save the value selected by user from drop downlist into database. but whatever value is selected by user, first value of dropdown lsit is saved to database View <% =Html.DropDownList("lstUsertype", (SelectList)ViewData["UserTypeID"])%> Controller public ActionResult CreateUser() { UmUser _UmUser = new UmUser(); UMRepository _UMRepository = new UMRepository(); EvoLetDataContext db = new EvoLetDataContext(); ViewData["UserTypeID"] = new SelectList(_UMRepository.FillUserTypes(), "UserTypeID", "UserType",2); return View(_UmUser); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult CreateUser(UmUser _umUser) { //try //{ if (ModelState.IsValid) { //try //{ UserRepository _UserRepository = new UserRepository(); _UserRepository.Add(_umUser); _UserRepository.Save(); return RedirectToAction("Details", new { id = _umUser.UserID }); /*} catch { ModelState.AddModelErrors(_umUser.GetRuleViolations()); }*/ } return View(); //} /*catch { return View(); }*/ }

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  • nHibernate query looking for the related object's related object

    - by code-zoop
    I have an nHibernate querie issue that looks quite straight forward, but I can't seem to get my head around it! I am creating some simple example classes to illustrate my problem: public class Car { public int Id { get; set; } public IList<Interior> InteriorParts { get; set; } } public class Interior { public int Id { get; set; } public InteriorProducer Producer { get; set; } } public class InteriorProducer { public int Id { get; set; } } Now to the query: I have the id of the InteriorProducer, but need to get a list of Cars where the interior have been produced by the interior producer. So in a simple, pseudo SQL, it looks something like this: select cars where car.InteriorParts.Producer.Id = Id I have a really hard time getting my head around this to create an nHibernate query. Any Ideas? Thanks

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  • Cakephp - detect if unable to connect to database and recover gracefully

    - by Phantz
    I have a few sites built with Cakephp. If any of these sites lose their connection to the database for whatever reason it does not handle it well. Basically it renders itself inside itself trying to display an error over and over until the browser crashes. The rendering itself inside itself is caused by the use of requestAction from elements. What I want to know is how can I check if the database connection exists I tried this in the app_controller before filter: if(!ConnectionManager::getDataSource('default')) { die(); //this will be a message instead } but it does not seem to work. Thanks

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  • Repeating fields in similar database tables

    - by user1738833
    I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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  • Access one database from multiple ORMs :: Caching issue

    - by kaptan
    I know this is not a good idea and the best would be to let the applications talk Web Services. But I have a situation where the legacy application is accessing a database with an ORM and I need to access the same database from the new .net application using Fluent nHibernate. So the question is what problems this will make and how to solve them? I guess the main issue is the caching. I need to disable the caching on one of the applications (which would be the new app). So how can I disable caching in nHibernate? Is there anything else that should be careful about?

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  • question on database query using hibernate in java with annotations

    - by molleman
    Hello, simple question regarding HQL(Hibernate query language) so i have user class , that can hold a list of Projects, how do i take this out of the database depending on a username, this is how i take out my user String username = "stephen"; YFUser user = (YFUser) session.createQuery("select u FROM YFUser u where u.username = :username").setParameter("username", name).uniqueResult(); but i want to take out the list of projects here is the projects list within the class YFUser(my user class); how would i query the database to get this list of projects @Entity @Table(name = "yf_user_table") public class YFUser implements Serializable,ILightEntity { ......... @OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY) @JoinTable(name = "YFUSER_JOIN_PROJECT", joinColumns = { @JoinColumn(name = "user_id") }, inverseJoinColumns = { @JoinColumn(name = "project_id") }) private List<Project> projects = new ArrayList<Project>();

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  • What ORMs work well with Scala?

    - by Clinton R. Nixon
    I'm about to write a Scala command-line application that relies on a MySQL database. I've been looking around for ORMs, and am having trouble finding one that will work well. The Lift ORM looks nice, but I'm not sure it can be decoupled from the entire Lift web framework. ActiveObjects also looks OK, but the author says that it may not work well with Scala. I'm not coming to Scala from Java, so I don't know all the options. Has anyone used an ORM with Scala, and if so, what did you use and how well did it work?

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  • Instrumenting Database Access

    - by Whisk
    Jeff mentioned in one of the podcasts that one of the things he always does is put in instrumentation for database calls, so that he can tell what queries are causing slowness etc. This is something I've measured in the past using SQL Profiler, but I'm interested in what strategies other people have used to include this as part of the application. Is it simply a case of including a timer across each database call and logging the result, or is there a 'neater' way of doing it? Maybe there's a framework that does this for you already, or is there a flag I could enable in e.g. Linq-to-SQL that would provide similar functionality. I mainly use c# but would also be interested in seeing methods from different languages, and I'd be more interested in a 'code' way of doing this over a db platform method like SQL Profiler.

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  • visual c# 2008 database application examples

    - by Omar
    hi, i just have a few weeks programming with vc# (2008) and i'm trying to build an application (winforms) and i have the following problem... i need my application to work with and without connection to the mssql database, this sounds like piece of cake for our friend DataSet right? i can persist the data as XML or binary until i can reach the database and the DataSet will magically sync; all without bothering the user. The problem is... the few books i have read just mention that logic like a fairy tale but dont give any practical example of how to do it, can you point me to one example/demo/whatever i can read or download of an application with (equal or) similar logic?

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  • Database design - alternatives for Entity Attribute Value (AEV)

    - by Bob
    Hi, see http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters for similar topic. My question: i want to design a database, that will be used for a production facility of different types of products where each product has its own (number of) parameters. because i want the serial numbers to be in one tabel for overview purposes i have a problem with these different paraeters . One solution could be AEV, but it has its downsides, certainly because we have +- 5 products with every product +- 20.000 serial numbers (records). it looks a bit overkill to me... I just don't know how one could design a database so that you have an attribute in a mastertable that says: 'hey, you could find details of this record in THAT detail-table". 'in a way that you qould easely query the results) currenty i am using Visual Basic & Acces 2007. but i'm going to Visual Basic & MySQL. thanks for your help. Bob

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  • Cache for large read only database recommendation

    - by paddydub
    I am building site on with Spring, Hibernate and Mysql. The mysql database contains information on coordinates and locations etc, it is never updated only queried. The database contains 15000 rows of coordinates and 48000 rows of coordinate connections. Every time a request is processed, the application needs to read all these coordinates which is taking approx 3-4 seconds. I would like to set up a cache, to allow quick access to the data. I'm researching memcached at the moment, can you please advise if this would be my best option?

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  • Oracle database connection string PLSQL compatibility

    - by user521180
    Hi I'm using an application called Logi info. it requires a connection string to my oracle database. the connection works fine but in order to configure the connection to recive ref cursors from the database, I apparently need to add PLSQLRSet=1 to the end of the string. when I do that I recieve an error "invalid connection string" Here is my connection string without plsqlrset=1 Data Source=SID; User Id=username; Password=password; My concern is that PLSQLRSet=1 might be .NET paramater only. Can anyone shed some light on the issue. Thanks

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