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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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  • '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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  • 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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  • 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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  • 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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  • Saving image to database as varbinary, arraylength (part 2)

    - by Thomas Schoof
    This is a followup to my previous question, which got solved (thank you for that) but now I am stuck at another error. I'm trying to save an image in my database (called 'Afbeelding'), for that I made a table which excists of: id: int souce: varbinary(max) I then created a wcf service to save an 'Afbeelding' to the database. private static DataClassesDataContext dc = new DataClassesDataContext(); [OperationContract] public void setAfbeelding(Afbeelding a) { //Afbeelding a = new Afbeelding(); //a.id = 1; //a.source = new Binary(bytes); dc.Afbeeldings.InsertOnSubmit(a); dc.SubmitChanges(); } I then put a reference to the service in my project and when I press the button I try to save it to the datbase. private void btnUpload_Click(object sender, RoutedEventArgs e) { Afbeelding a = new Afbeelding(); OpenFileDialog openFileDialog = new OpenFileDialog(); openFileDialog.Filter = "JPEG files|*.jpg"; if (openFileDialog.ShowDialog() == true) { //string imagePath = openFileDialog.File.Name; //FileStream fileStream = new FileStream(imagePath, FileMode.Open, FileAccess.Read); //byte[] buffer = new byte[fileStream.Length]; //fileStream.Read(buffer, 0, (int)fileStream.Length); //fileStream.Close(); Stream stream = (Stream)openFileDialog.File.OpenRead(); Byte[] bytes = new Byte[stream.Length]; stream.Read(bytes, 0, (int)stream.Length); string fileName = openFileDialog.File.Name; a.id = 1; a.source = new Binary { Bytes = bytes }; } EditAfbeeldingServiceClient client = new EditAfbeeldingServiceClient(); client.setAfbeeldingCompleted +=new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(client_setAfbeeldingCompleted); client.setAfbeeldingAsync(a); } void client_setAfbeeldingCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e) { if (e.Error != null) txtEmail.Text = e.Error.ToString(); else MessageBox.Show("WIN"); } However, when I do this, I get the following error: System.ServiceModel.FaultException: The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter :a. The InnerException message was 'There was an error deserializing the object of type OndernemersAward.Web.Afbeelding. The maximum array length quota (16384) has been exceeded while reading XML data. This quota may be increased by changing the MaxArrayLength property on the XmlDictionaryReaderQuotas object used when creating the XML reader.'. Please see InnerException for more details. at System.ServiceModel.Channels.ServiceChannel.HandleReply(ProxyOperationRuntime operation, ProxyRpc& rpc) at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result) at System.ServiceModel.ClientBase`1.ChannelBase`1.EndInvoke(String methodName, Object[] args, IAsyncResult result) atOndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.EditAfbeeldingServiceClientChannel.EndsetAfbeelding(IAsyncResult result) at OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingService.EndsetAfbeelding(IAsyncResult result) at OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.OnEndsetAfbeelding(IAsyncResult result) at System.ServiceModel.ClientBase`1.OnAsyncCallCompleted(IAsyncResult result) I'm not sure what's causing this but I think it has something to do with the way I write the image to the database? (The array length is too big big, I don't really know how to change it) Thank you for your help, Thomas

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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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  • 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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  • 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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  • 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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  • 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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  • C# database file directory

    - by Simon
    I'm using the windows forms aplication with an ms access database. And i would like to know if there is a way to show the directory of the database file (to save data in it)excpet like this: string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=save.mdb"; or this: "Data Source=D:\Simonova aktovka na namizju\matura\test5\save.mdb"; couse if i use the first one the aplication undos the changes i've made when i close it(the aplication) the second one makes me have to change the path everytime i bring the aplication to another computer(cous the direktory is different of coars) So... is there another way?

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  • Methods of pulling data from a database

    - by kingrichard2005
    I'm getting ready to start a C# web application project and just wanted some opinions regarding pulling data from a database. As far as I can tell, I can either use C# code to access the database from the code behind (i.e. LINQ) of my web app or I can call a stored procedure that will collect all the data and then read it with a few lines of code in my code behind. I'm curious to know which of these two approaches, or any other approach, would be the most efficient, elegant, future proof and easiest to test.

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  • The conceptual process of populating related tables in a database (MySql) from a CSV file

    - by user322772
    I'm new to relational databases and all the material I've read covered primary and foreign keys, normal forms, and joins but left out to populate the database once it's created. How do you import a CSV file so the fields match their related table? Say you were tying to build a beer database and had a CSV file with each line as a record. Header: brewer, beer_name, country, city, state, beer_category, beer_type, alcohol_content Record 1: Anheuser-Busch, Budweiser, United States, St. Louis, Mo, Pale lager, Regular, 5.0% Record 2: Anheuser-Busch, Bud Light, United States, St. Louis, Mo, Pale lager Light, 4.2% Record 3: Miller Brewing Company, Miller Lite, United States, Milwaukee, WI, Pale lager, Light, 4.2% You can create a "Brewer" table and a "Beer" table. When importing how does you connect the primary keys between the tables?

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  • Choosing proper database for a few users application

    - by tomo
    Requirements: tiny WinForms client app (C# 4.0, WinForms or WPF) a few users working simultinausly no database service at all - the whole engine as *.DLLs inside client apps database available as shared folder on one computer at least simple concurrrency checks compatible with nHibernate or EntityFramework / NET 4.0 backup as simple as copying files from shared folder - assuming no running clients at the moment no stored procedures/triggers required data size - a few tables and a few thousands rows after 2 years Nice to have: user access rights encrypted data I'm trying to choose between: MS Access SqlLite SqlServer Compact Edition. Can you recommend which one should be the best for these requirements?

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  • Database schema publishing with SQL Server 2005/2008

    - by Marconline
    Hi everybody, I've a question for you. We have built a software that has a single database for each customer. These databases are managed by SQL Server 2008. Now the problem is that when we build our software we, sometimes, need to change something on the schema (like adding table, modifying existing ones etc) and migrate these updates on all the customers' databases. Now this task is accomplished by hand: we generate update scripts and then, using T-SQL, we update each database. This is ok for a small set of customer, but we are now becoming bigger and bigger and we really don't know how to face it. We found Wizardby and it seems interesting, but quite difficult for us to learn in this exact moment. Do you have any other trick? Thanks a lot, Marco

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  • Vehicle Make/Model and Parts Database

    - by Jas Panesar
    I am looking to see if there is a web based service I can either access programmatically to access teh following information, or a database I could purchase or interface with. I am looking to see if there are databases out there for: 1) Vehicle makes and models -- I recall something being out there in the $500/yr range 2) Vehicle Part Numbers - A database of car part numbers that is maintained and updated for a yearly subscription. I had read something similar about databases being purchased for other industries on SO.. so I figure this is fair game. Thanks in advance!

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