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  • Getting the relational table data into XML recursively

    - by Tom
    I have levels of tables (Level1, Level2, Level3, ...) For simplicity, we'll say I have 3 levels. The rows in the higher level tables are parents of lower level table rows. The relationship does not skip levels however. E.g. Row1Level1 is parent of Row3Level2, Row2Level2 is parent of Row4Level3. Level(n-1)'s parent is always be in Level(n). Given these tables with data, I need to come up with a recursive function that generates an XML file to represent the relationship and the data. E.g. <data> <level levelid = 1 rowid=1> <level levelid = 2 rowid=3 /> </level> <level levelid = 2 rowid=2> <level levelid = 3 rowid=4 /> </level> </data> I would like help with coming up with a pseudo-code for this setup. This is what I have so far: XElement GetXMLData(Table table, string identifier, XElement data) { XElement xmlData = data; if (table != null) { foreach (row in the table) { // Get subordinate table Table subordinateTable = GetSubordinateTable(table); // Get the XML Data for the children of current row xmlData += GetXMLData(subordinateTable, row.Identifier, xmlData); } } return xmlData; }

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  • Design: How to model / where to store relational data between classes

    - by Walker
    I'm trying to figure out the best design here, and I can see multiple approaches, but none that seems "right." There are three relevant classes here: Base, TradingPost, and Resource. Each Base has a TradingPost which can offer various Resources depending on the Base's tech level. Where is the right place to store the minimum tech level a base must possess to offer any given resource? A database seems like overkill. Putting it in each subclass of Resource seems wrong--that's not an intrinsic property of the Resource. Do I have a mediating class, and if so, how does it work? It's important that I not be duplicating code; that I have one place where I set the required tech level for a given item. Essentially, where does this data belong? P.S. Feel free to change the title; I struggled to come up with one that fits.

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  • What relational database system should I learn? [closed]

    - by acidzombie24
    At the moment i know sqlite (my favorite), mysql (its ok, i get annoyed) and i do not want to learn ms/t sql (it only allows one nullable row if the column is unique). I am thinking about learning a new database system. My requirements for it is Must allow multiple connections at once (read and write) All or data i choose must be ACID compliant Performance should be good. I have a 17gb table in one project. It should perform well on read and transactional writes. With mysql it took hours to restore it and there were no foreign keys on that specific table. It only finished in a workday because i found a suggestion to adjust a setting which i think was key-buffer. And it still took hours Unique columns that allow more then one row to be null. I shouldn't have to say it but dammit MS. Allows one to make ongoing backups. Something like 'binary logs'. Some relatively small amounts of data i can grab and apply it to my local db to have it in sync with the one on the server. Table joins. I rather not write a bunch of queries to simulate a join What I would like but is not required Foreign keys. This may be a requirement later Open sourced Fair tool support. So i can measure queries, easily backup/restore, etc .NET and C (or C++) interface. (I seen one that uses raw tcp with JSON which was okish) Good subquery support. Once i was working with an older version of mysql (i believe <5.1 but it could have been 5.1) and i had to write many queries to do one query because it couldn't do subqueries. Or maybe it couldnt do it efficiently and died bc of memory limitations with a huge dataset. What db system should i learn?

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  • Quiz Master at Beyond Relational

    - by Vincent Maverick Durano
    Last month a friend of mine invited me to join BeyondRelational.com and asked me to nominate myself as a .NET Quiz Master. In order to qualify I must submit an interesting question related to .NET and their .NET team will review the information and will select 31 quiz masters for the .NET quiz category. This seems insteresting to me so I go ahead and submit one entry. Luckily I was selected as one of the 31 Quiz Masters in the .NET category. I hope to be able to keep up the good work there for years to come. Big Thanks to Jacob Sebastian and his Team! And oh.. I didn't get a changce to blog about this last week but just to let you guys know that the .NET General Quiz just started last january 1st 2011. The quiz will be a series of 31 questions, managed by 31 .NET quiz masters. Each quiz master will ask one question and will moderate the discussion and answers and finally will identify the winner of each quiz. Each answer that is correct will get a certain score ranging from 1 to 10 where 10 is the highest. The scores of all 31 questions will be added up to identify the final winner. So what are you waiting for? Sign-up and register now and get a changce to win some exciting prizes! Technorati Tags: Community

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  • What is the most easy way to get in advanced Type Theory.

    - by Bubba88
    Of course, by 'advanced' I mean here just something beyond what every programmer does know. I'm currently more-or-less comfortable with the basics and want to understand the most important, most elegant and most practically applicable achievements of modern type theory. I just do not have much time, desire and mental powers to study all the formalistics more thoroughly and that may change in the future. But there is something really attractive for me in that branch, that just forces to ask silly questions like this :) Thank you very much!

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  • Theory: Can JIT Compiler be used to parse the whole program first, then execute later?

    - by unknownthreat
    Normally, JIT Compiler works by reads the byte code, translate it into machine code, and execute it. This is what I understand, but in theory, is it possible to make the JIT Compiler parses the whole program first, then execute the program later as machine code? I do not know how JIT Compiler works technically and exactly, so I don't know any feasibility in this case. But theoretically, is it possible? Or am I doing it wrong?

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  • The Boss Answer: What is a relational database?

    - by kce
    I'm mostly a system administrator and I don't directly work with databases other than installing them, setting up accounts, granting privileges, and so on. I realized that if The Boss walked up to me and asked, "What is a relational database?" I probably couldn't give a satisfactory answer... I'd maybe mumble something about data being stored and organized by categories which you can query with a special programing language (i.e., SQL). So could someone give a good "Boss Answer" for what a relational database is? And maybe how its different than just storing data on a file server? Bonus points for clever but accessible analogies and explaining tables, columns, records and fields. I'd define a "Boss Answer" as a quick one (maybe two) paragraph explanation for non-technical folks... mostly your Boss, on those rare occasions they actually ask you what it is you do all day.

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  • How could RDBMSes be considered a fad?

    - by StuperUser
    Completing my Computing A-level in 2003 and getting a degree in Computing in 2007, and learning my trade in a company with a lot of SQL usage, I was brought up on the idea of Relational Databases being used for storage. So, despite being relatively new to development, I was taken-aback to read a comment (on Is LinqPad site quote "Tired of querying in antiquated SQL?" accurate? ) that said: [Some devs] despise [SQL] and think that it and RDBMS are a fad Obviously, a competent dev will use the right tool for the right job and won't create a relational database when e.g. flat file or another solution for storage is appropriate, but RDBMs are useful in a massive number of circumstances, so how could they be considered a fad?

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  • Designing persistence schema for BigTable on AppEngine

    - by Vitalij Zadneprovskij
    I have tried to design the datastore schema for a very small application. That schema would have been very simple, if not trivial, using a relational database with foreign keys, many-to-many relations, joins, etc. But the problem was that my application was targeted for Google App Engine and I had to design for a database that was not relational. At the end I gave up. Is there a book or an article that describes design principles for applications that are meant for such databases? The books that I have found are about programming for App Engine and they don't spend many words about database design principles.

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  • How would you solve this graph theory handshake problem in python?

    - by Zachary Burt
    I graduated college last year with a degree in Psychology, but I also took a lot of math for fun. I recently got the book "Introductory Graph Theory" by Gary Chartrand to brush up on my math and have some fun. Here is an exercise from the book that I'm finding particularly befuddling: Suppose you and your husband attended a party with three other married couples. Several handshakes took place. No one shook hands with himself (or herself) or with his (or her) spouse, and no one shook hands with the same person more than once. After all the handshaking was completed, suppose you asked each person, including your husband, how many hands he or she had shaken. Each person gave a different answer. a) How many hands did you shake? b) How many hands did your husband shake? Now, I've been reasoning about this for a while, and trying to draw sample graphs that could illustrate a solution, but I'm coming up empty-handed. My logic is this: there are 8 different vertices in the graph, and 7 of them have different degrees. The values for the degrees must therefore be 0, 1, 2, 3, 4, 5, 6, and x. The # of degrees for one married couple is (0, 6). Since all graphs have an even number of odd vertices, x must be either 5, 3, or 1. What's your solution to this problem? And, if you could solve it in python, how would you do it? (python is fun.) Cheers.

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  • How would you solve this graph theory handshake problem in python?

    - by Zachary Burt
    I graduated college last year with a degree in Psychology, but I also took a lot of math for fun. I recently got the book "Introductory Graph Theory" by Gary Chartrand to brush up on my math and have some fun. Here is an exercise from the book that I'm finding particularly befuddling: Suppose you and your husband attended a party with three other married couples. Several handshakes took place. No one shook hands with himself (or herself) or with his (or her) spouse, and no one shook hands with the same person more than once. After all the handshaking was completed, suppose you asked each person, including your husband, how many hands he or she had shaken. Each person gave a different answer. a) How many hands did you shake? b) How many hands did your husband shake? Now, I've been reasoning about this for a while, and trying to draw sample graphs that could illustrate a solution, but I'm coming up empty-handed. My logic is this: there are 8 different vertices in the graph, and 7 of them have different degrees. The values for the degrees must therefore be 0, 1, 2, 3, 4, 5, 6, and x. The # of degrees for one married couple is (0, 6). Since all graphs have an even number of odd vertices, x must be either 5, 3, or 1. What's your solution to this problem? And, if you could solve it in python, how would you do it? (python is fun.) Cheers.

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  • Relational databases are not suited for my application - what's the alternative?

    - by waitinforatrain
    Hi, I'm writing a CMS in PHP that allows the user to define different fields (e.g. a Blog page could have fields for Title (string), Content (rich text), Picture (file)). I need the user to be able to add and remove fields dynamically, and the only way I can think of to do it with relational DBs is to serialise all these values and store them in one cell. This seems like a slow approach and like I'm trying to fit something dynamic within a static structure. Could someone recommend anything that is PHP-compatible that would make this easier?

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  • Are document-oriented databases any more suitable than relational ones for persisting objects?

    - by Owen Fraser-Green
    In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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  • Are GUID primary keys bad in theory, or just practice?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • XML flat file vs. relational database backend

    - by donpal
    Most projects now need some form of a database. When someone says database, I usually think relational databases, but I still hear about flat file XML databases. What parameters do you take into consideration when deciding between a "real" database and a flat-file XML database. When should one be used over the other, and under what circumstances should I never consider using a flat file (or vice versa a relational) database?

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  • Relational database question with php.

    - by Oliver Bayes-Shelton
    Hi, Not really a coding question more a little help with my idea of a Relational database. If I have 3 tables in a SQL database. In my php script I basically query the companies which are in industry "a" and then insert a row into a separate table with their details such as companyId , companyName etc is that a type of Relational database ? I have explained it in a simple way so we don't get confused what I am trying to say.

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  • Relational database queestion with php.

    - by Oliver Bayes-Shelton
    Hi, Not really a coding question more a little help with my idea of a Relational database. If I have 3 tables in a SQL database. In my php script I basically query the companies which are in industry "a" and then insert a row into a seperate table with their details such as companyId , companyName etc is that a type of Relational database ? I have explained it in a simple way so we don't get confused what I am trying to say.

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  • Modeling Tools that understand both Relational and LDAP

    - by jm04469
    I am looking to do some modeling and would like to have a tool that can capture not only a relational model like ERWIN but also allow us to easily port to LDAP as an option. NOTE: Visio can connect to an existing LDAP server and draw, but does not allow for you to model first and then deploy, unlike its relational capabilities.

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  • Cuppa Corner talk "A trip to First Normal Form" available - Domains, Functional Dependencies, Repeat

    - by tonyrogerson
    It's 15 minutes, I talk about Domains, Functional Dependencies, Repeating Groups, Relational Valued Attributes and of course First Normal Form. http://sqlcontent.sqlblogcasts.com/video/cctr20100507dbdesign1nf/cctr20100507dbdesign1nf.html For questions just ask on the http://sqlserverfaq.com chat control or Twitter using #sqlfaq tag. Slides are also availble here: http://sqlcontent.sqlblogcasts.com/video/cctr20100507dbdesign1nf/cc_tr20100507_dbdesign1nf.pptx...(read more)

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  • Technology Selection for a dynamic product

    - by Kuntal Shah
    We are building a product for Procurement Domain in JAVA. Following are the main technical requirements. Platform Independent Database Independent Browser Independent In functional requirements the product is very dynamic in nature. The main reason being the procurement process around the world is different from client to client. Briefly we need to have a dynamic workflow engine and a dynamic template engine. The workflow engine by which we can define any kind of workflows and the template engine allows us to define any kind of data structures and based on definition it can get the user input through workflow. We have been developing this product for almost 2 years. It has been a long time till we can get down with the dynamics of requirements. Till now we have developed a basic workflow and template engine and which is in use at one of the client. We have been using following technologies. GWT-Ext (Front End Framework) Hibernate (Database Layer) In between we have faced some issues with GWT-Ext (mainly browser compatibility) and database optimization due to sub classing in hibernate. For resolving GWT-Ext issue, which a dying community so we decided to move to SmartGWT. In SmartGWT we faced issues related to loading and now we are able to finalize that GWT 2.3 will be the way to go as the library is rich and performance is upto the mark. We are able to almost finalize GWT-Spring based front and middle layer. In hibernate, we found main issues with sub-classing due to that it was throwing astronomical queries and sometimes it would stop firing any queries for 5-10 seconds or may be around 30 seconds and then resume again. Few days back I came to one article related to ORM. I am a traditional .Net SQL developer and I have always worked with relational database. Reading through this article, I also found it relating to the issues I face. I am still not completely convinced of using hibernate and this article just supported my opinion. Following are the questions for which I am looking for an answer. Should we be going with Hibernate in case of dynamic database requirements and the load of the data will be heavy in future? How can we partition the data, how we can efficiently join the data, how we can optimize the queries? If the answer is no then how do we achieve database independence? Is our choice related to GWT and Spring proper or do we need to change that too? Should we use any other key value pair database if the data is dynamic in nature and it is very difficult to make it relational?

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  • Should database-models (conceptual or physical) be reviewed by DBAs?

    - by user61852
    Where I work, new applications that are being developed that will use their own relational database, must have their database-models (conceptual, then physical ) reviewed and aproved by DBAs. Things looked after are normalization, antipatterns, table and column naming standards, etc. Is this really a DBA's responsability to do this ? or should it be, in a greater extend, the responsability of app designers and architects ?

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