Search Results

Search found 1042 results on 42 pages for 'relational calculus'.

Page 33/42 | < Previous Page | 29 30 31 32 33 34 35 36 37 38 39 40  | Next Page >

• Usual hibernate performance pitfall

  - by Antoine Claval

  Hi, We have just finish to profile our application. ( she's begin to be slow ). the problem seems to be "in hibernate". It's a legacy mapping. Who work's, and do it's job. The relational shema behind is ok too. But some request are slow as hell. So, we would appreciate any input on common and usual mistake made with hibernate who end up with slow response. Exemple : Eager in place of Lazy can change dramaticly the response time....

  Read the article

• Retrieving data from database. Retrieve only when needed or get everything?

  - by RHaguiuda

  I have a simple application to store Contacts. This application uses a simple relational database to store Contact information, like Name, Address and other data fields. While designing it, I question came to my mind: When designing programs that uses databases, should I retrieve all database records and store them in objects in my program, so I have a very fast performance or I should always gather data only when required? Of course, retrieving all data can only be done if it`s not too many, but do you use this approach when you make sure that the database will be small (< 300 records for example)? I have designed once a similar application that fetches data only when needed, but that was slow (using a Access database). Thanks for all help.

  Read the article

• What Can A 'TreeDict' (Or Treemap) Be Used For In Practice?

  - by Seun Osewa

  I'm developing a 'TreeDict' class in Python. This is a basically a dict that allows you to retrieve its key-value pairs in sorted order, just like the Treemap collection class in Java. I've implemented some functionality based on the way unique indexes in relational databases can be used, e.g. functions to let you retrieve values corresponding to a range of keys, keys greater than, less than or equal to a particular value in sorted order, strings or tuples that have a specific prefix in sorted order, etc. Unfortunately, I can't think of any real life problem that will require a class like this. I suspect that the reason we don't have sorted dicts in Python is that in practice they aren't required often enough to be worth it, but I want to be proved wrong. Can you think of any specific applications of a 'TreeDict'? Any real life problem that would be best solved by this data structure? I just want to know for sure whether this is worth it.

  Read the article

• I know the big picture but can't put it in place

  - by Simbilim

  Hi, I'm interested in web development and by that I mean the bigger projects like facebook or twitter. I know the basics of java, css, php and mysql. I know there is a lot more out there. I read about it. But I don't know what the purpose is and how to put in place. Things like: Scribe, thrift, casandra, Unix/Linux, shell/perl/python scripting, PostgreSQL, MongoDB, non-relational NoSQL datastores, JVM, nginx I want to know why they need it, how they use it and what te purpose is. What I need is a book like technical background of facebook for dummies or so. Are there any books or websites that explain this from scratch? Thank you!

  Read the article

• Solution for distributing MANY simple network tasks?

  - by EmpireJones

  I would like to create some sort of a distributed setup for running a ton of small/simple REST web queries in a production environment. For each 5-10 related queries which are executed from a node, I will generate a very small amount of derived data, which will need to be stored in a standard relational database (such as PostgreSQL). What platforms are built for this type of problem set? The nature, data sizes, and quantities seem to contradict the mindset of Hadoop. There are also more grid based architectures such as Condor and Sun Grid Engine, which I have seen mentioned. I'm not sure if these platforms have any recovery from errors though (checking if a job succeeds). What I would really like is a FIFO type queue that I could add jobs to, with the end result of my database getting updated. Any suggestions on the best tool for the job?

  Read the article

• Unique constraint on more than 10 columns

  - by tk

  I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

  Read the article

• What open source document-oriented database system is most mature for Windows usage?

  - by jdk

  After using relational databases as back-end storage all my Windows programming life (currently .NET), I want to experiment with a document-oriented database by this Wikipedia definition; it can be standalone or layered over an existing non-commercial database system. What open source document-oriented database solution would you recommend from your own experience and why? A nice to have would be a .NET provider. Admittedly this is somewhat subjective and potentially argumentative so keep it real folks and I'll do the same - also your answers will be invaluable to others looking into document-oriented databases for the first time on Windows. I'm sure the overall value of your answers will outweigh any biases. Thanks.

  Read the article

• How to structure opening hours of a place? May-be there's even an ontology for it?

  - by Ago

  Does anyone know any ontology which specifies opening hours of places? For example, I have a museum, which has 2 seasons. For low season (season start and end is specified), it is opened 10.00 - 18.00 on weekdays and 10-16 on saturday (on sunday it's closed), for high season it's opened 10-20 on weekdays and 10-18 on weekend. If there is no ontology, may-be people have experience, how best to structure information like that? I'm describing information in RDF. But whatever comments are welcome (even if you have relational database which holds given data). Thanks

  Read the article

• Storing Data as XML BLOB

  - by NBrowne

  Hi, At the moment the team i am working with is looking into the possibility of storing data which is entered by users from a series of input wizard screens as an XML blob in the database. the main reason for this being that i would like to write the input wizard as a component which can be brought into a number of systems without having to bring with it a large table structure. To try to clarify if the wizard has 100 input fields (for example) then if i go with the normal relational db structure then their will be a 1 to 1 relationship so will have 100 columns in database. So to get this working in another system will have to bring the tables,strore procedures etc into the new system. I have a number of reservations about this but i would like peoples opinions?? thanks

  Read the article

• How to return relationships in a custom un-typed dataservice provider

  - by monkey_p

  I have a custom .Net DataService and can't figure out how to return the data for relationships. The data base has 2 tables (Customer, Address). A Customer can have multiple addresses, but each address can only have on customer. I'm using Dictionary<string,object> as my data type. My question, for the following 2 urls how do i return the data. http://localhost/DataService/Customer(1)/Address http://localhost/DataService/Address(1)/Customer For the none relational queries I return a List<Dictionary<string,object>> So I imagined for the relation I should just populate the element with a either a Dictionary<string,object> for the single ones and a List<Dictionary<string,object>> for many relationships. But this just gives me a NullRefferenceException So what am I doing wrong?

  Read the article

• ADO.NET DataService Exception

  - by Ravi

  Hi, I am working on C#.Net with ADO.NET Dataservice. I try to update one record to relational tabel, when I reach context.SetLink() I am getting exception("The context is not currently tracking the entity"). I don't know how to solve this problem. My code is specified below. LogNote dbLogNote =logNote; LogSubSession dbLogSubSession = (from p in context.LogSubSession where p.UID == logNote.SubSessionId select p).First<LogSubSession>() as LogSubSession; context.AddToLogNote(dbLogNote); dbLogNote.LogSubSession = dbLogSubSession; context.SetLink(dbLogNote, "LogSubSession", dbLogSubSession); context.SaveChanges(); Here LogSubSession is a primary table and LogNote is a foreign table. I am updating data into foreign table based on primary key table. Thanks

  Read the article

• How do I take the advantage of the variable column key/value structure of Cassandra

  - by icejade

  If I have to predefine all the columns, how do I take the advantage of the variable column key/value structure of cassandra? If I use update table command, it will insert null for all the rows which don't have that column. This is same as relational DB. For example, for contact column family, I have name, phone, email. I have 100 contacts have all 3 field. Then number 101 contact has skype id which I want to add. If I use insert statement, it won't let me add skypeid since it's not defined in the CF. So I have to run alter statement to change the CF, then all the first 100 contacts will have a null field for each of them.

  Read the article

• Understanding NoSQL Data Modeling - blog application

  - by Rushabh RajeshKumar Padalia

  I am creating an blogging application in Node.js + MongoDB Database. I have used relational Database like MySQL before but this is my first experience with NoSQL database. So I would like to conform my MongoDB data models before I move further. I have decided my blogDB to have 3 collections post_collection - stores information about that article comment_collection - store information about comments on articles user_info_collection - contains user inforamtion PostDB { _"id" : ObjectID(...), "author": "author_name", "Date": new Date(....), "tag" : ["politics" , "war"], "post_title": "My first Article", "post_content": "Big big article" "likes": 23 "access": "public" } CommentDB { "_id" : Objectid(...), "POST": "My First Article", "comment_by": "User_name", "comment": "MY comments" } UserInfoDB { "_id": ObjectID(...), "user": "User_name", "password": "My_password" } I would appreciate your comments.

  Read the article

• A better understanding of the relations beetween database tables

  - by Nistor Alexandru

  Hi I am trying to get a better understanding of relational databases and there is something that I keep bumping into and don't understand.Let's take this two tables: In this case Login.ID is the primary key with auto_increment set and Profile.ID_LOGIN is the Foreign KEY.When a user is created and it's username and password is stored in the login database does the ID coresponding to the curesnt username and password get automaticly added into ID_LOGIN or do I have to create an SQL statement to do this? If I have to create a SQL statement how should I aproach adding the ID_LOGIN to make sure I am adding it corectly?

  Read the article

• Is there a tool that will show diagrams of my SQL database in real-time?

  - by Rising Star

  I've created some diagrams of SQL tables using the "Reverse Engineer" feature of Microsoft Office Visio. I like being able to visualize my relational databases in this manner. However, what I get is just a static document that I can print, e-mail to colleagues, and click widgets on. Earlier this year, I saw at a demo that the new version of Visual Studio 2010 has a new feature called the "Architect Explorer", which allows developers to view relationships among .net classes on the fly. It has many features for filtering the data that the developer is interested in. It would be really awesome if I could visually browse my tables and stored procedures and see what is related to what by primary key, foreign key, and referenced in stored procedures. I realize that I'm talking about two entirely different technologies and it's not a perfect analogy, but is there some similar tool that would allow me to visualize tables in my SQL database?

  Read the article

• Sphinx without using an auto_increment id

  - by squeeks

  I am current in planning on creating a big database (2+ million rows) with a variety of data from separate sources. I would like to avoid structuring the database around auto_increment ids to help prevent against sync issues with replication, and also because each item inserted will have a alphanumeric product code that is guaranteed to be unique - it seems to me more sense to use that instead. I am looking at a search engine to index this database with Sphinx looking rather appealing due to its design around indexing relational databases. However, looking at various tutorials and documentation seems to show database designs being dependent on an auto_increment field in one form or another and a rather bold statement in the documentation saying that document ids must be 32/64bit integers only or things break. Is there a way to have a database indexed by Sphinx without auto_increment fields as the id?

  Read the article

• FastObjects.NET(is an OODB from Versant) performence in Real Scenerios?

  - by Lalit

  FastObjects.NET Saves the whole class object(if marked with attribute Persistent) at once in file system(using serilization or similar technology). They are promissing that it is even faster then normal SQL DB approach. My team also thought it is better and faster to save the whole object once instead of each field one by one. Defination of their website: FastObjects .NET 10.0 fully conforms to the Microsoft.NET 2.0 framework. Tightly integrated with Visual Studio 2005, it offers a developer-friendly, object-oriented alternative to a relational database for .NET persistence. I want to have your experiences of using FastObjects in production scenerio? They are promising for Indexing/Transaction/clustoring/replication.

  Read the article

• A step-up from TiddlyWiki that is still 100% portable?

  - by Smandoli

  TiddlyWiki is a great idea, brilliantly implemented. I'm using it as a portable personal "knowledge manager," and these are the prize virtues: It travels on my USB flash memory stick and runs on any computer, regardless of operating system No software installation is needed on the computer (TiddlyWiki merely uses the Internet browser) No Internet connection is needed In terms of data retrieval functionality, it mimics a relational database (use of tags and internal links) Let's say I've got a million words of prose in 4,000 tiddlers (posts). I'm still testing, but it looks like TiddlyWiki gets very slow. Is there an app like TiddlyWiki that keeps all the virtues I listed above, and allows more storage? NOTE: Separation of content and presentation would be ideal. It's nifty that TiddlyWiki has everything in a single HTML document, but it's unhelpful in many ways. I don't care if a directory of assorted docs is needed (SQLite, XML?), as long as it's functionally self-contained.

  Read the article

• Using linked servers, OPENROWSET and OPENQUERY

  - by BuckWoody

  SQL Server has a few mechanisms to reach out to another server (even another server type) and query data from within a Transact-SQL statement. Among them are a set of stored credentials and information (called a Linked Server), a statement that uses a linked server called called OPENQUERY, another called OPENROWSET, and one called OPENDATASOURCE. This post isn’t about those particular functions or statements – hit the links for more if you’re new to those topics. I’m actually more concerned about where I see these used than the particular method. In many cases, a Linked server isn’t another Relational Database Management System (RDMBS) like Oracle or DB2 (which is possible with a linked server), but another SQL Server. My concern is that linked servers are the new Data Transformation Services (DTS) from SQL Server 2000 – something that was designed for one purpose but which is being morphed into something much more. In the case of DTS, most of us turned that feature into a full-fledged job system. What was designed as a simple data import and export system has been pressed into service doing logic, routing and timing. And of course we all know how painful it was to move off of a complex DTS system onto SQL Server Integration Services. In the case of linked servers, what should be used as a method of running a simple query or two on another server where you have occasional connection or need a quick import of a small data set is morphing into a full federation strategy. In some cases I’ve seen a complex web of linked servers, and when credentials, names or anything else changes there are huge problems. Now don’t get me wrong – linked servers and other forms of distributing queries is a fantastic set of tools that we have to move data around. I’m just saying that when you start having lots of workarounds and when things get really complicated, you might want to step back a little and ask if there’s a better way. Are you able to tolerate some latency? Perhaps you’re able to use Service Broker. Would you like to be platform-independent on the data source? Perhaps a middle-tier might make more sense, abstracting the queries there and sending them to the proper server. Designed properly, I’ve seen these systems scale further and be more resilient than loading up on linked servers. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

  Read the article

• SQLAuthority News – Book Review – Beginning T-SQL 2008 by Kathi Kellenberger

  - by pinaldave

  Beginning T-SQL 2008 by Kathi Kellenberger Amazon Link Detail Review: Beginning T-SQL 2008 is one of the best books on the market if you are just beginning to work with Microsoft SQL, or have a little bit of experience and need to learn more quickly. Each chapter of the book introduces a new subject, and builds upon topics covered in previous chapters.  The author of the book, Kathi Kellenberger understands that you need to form a solid foundation of knowledge before moving on to new topics, and sets up each subject nicely.  Because the chapters move in an orderly progression, you continue to use skills you learned earlier. One of the best features of Beginning T-SQL 2008 is that each chapter has multiple examples and exercises.  Many books introduce a topic and then never go back to it.  This book gives enough examples that you will be familiar with the subject when you come across it in real life.  The exercises at the end of the chapter mean that you will be using the skills you learned – and there is no better way to cement a subject in your brain. The book also includes discussions of the common errors that programmers will come across, how to avoid them, and how to fix them if they happen.  Ms. Kellenberger understands that not only do mistakes happen, but they are bound to happen if you aren’t trained properly.  Mistakes are part of the learning process! The book begins by discussions relational theory, so that programmers will understand the way T-SQL works from the ground up.  It also walks readers through writing accurate queries, combining set-based and procedural processing, embedding logic in stored functions, and so much more. Overall, the main goal of Beginning T-SQL 2008 is to introduce novices to SQL programming, and quickly familiarize them with the basics of running the program.  The book is written with the idea that readers will not know any of the technical terms or vocabulary.  However, if you are a little more familiar with SQL and looking to become better, you will still find this book very helpful. Ratting: 4.5+ Stars Summary: I must recommend Beginning T-SQL 2008 highly enough.  If you are going to buy any beginners guide to Transect-SQL, this is the one you should spend your money on.  You can save yourself a lot of time and effort later by using this very affordable manual to learn the basics, which will allow you to become an expert much faster. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Book Review, SQLAuthority News, T SQL, Technology

  Read the article

• Learn about MySQL with the Authentic MySQL for Beginners course

  - by Antoinette O'Sullivan

  Learn about the MySQL Server and other MySQL products by taking the authentic MySQL for Beginners course. This course covers all the basics from MySQL download and installation, to relational database concepts and database design. This course is your first step to becoming a MySQL administrator. You can take this course through one of the following delivery types: Training-on-Demand: Start the class from your desk, at your base and within 24 hrs of registering. Read Ben Krug on Day 3 of his experience taking the MySQL for Beginners course Training-on-Demand option. Live-Virtual Class: Attend this live class from your own office - no travel required. Choose from a selection of events on the schedule to suit different timezones. Delivery languages include English and German. In-Class event: Attend this class in an education center. Events already on the schedule include:  Location  Date  Delivery Language  Mechelen, Belgium  14 January 2013  English  London, England  5 March 2013  English  Hamburg, Germany  25 March 2013  German  Munich, Germany  3 June 2013  German  Budapest, Hungary  5 February 2013  Hungary  Milan, Italy  11 February 2013  Italian  Rome, Italy  4 March 2013  Italian  Riga, Latvia  18 February 2013  Latvian  Amsterdam, Netherlands  21 May 2013  Dutch  Nieuwegein, Netherlands  18 February 2013  Dutch  Warsaw, Poland  18 February 2013  Polish  Lisbon, Portugal  25 March 2013  European Portugese  Porto, Portugal  25 March 2013  European Portugese  Barcelona, Spain  11 February 2013  Spanish  Madrid, Spain  22 April 2013  Spanish  Nairobi, Kenya  14 January 2013  English  Capetown, South Africa  22 July 2013  English  Pretoria, South Africa  22 April 2013  English  Petaling Jaya, Malaysia  28 January 2013  English  Ottawa, Canada  25 March 2013  English  Toronto, Canada  25 March 2013  English  Montreal, Canada 25 March 2013   English Mexico City, Mexico  14 January 2013   Spanish  San Pedro Garza Garcia, Mexico  5 February 2013  Spanish  Sao Paolo, Brazil  29 January 2013  Brazilian Portugese For more information on this or other courses on the authentic MySQL Curriculum, go to http://oracle.com/education/mysql. Note, many organizations deploy both Oracle Database and MySQL side by side to serve different needs, and as a database professional you can find training courses on both topics at Oracle University! Check out the upcoming Oracle Database training courses and MySQL training courses. Even if you're only managing Oracle Databases at this point of time, getting familiar with MySQL will broaden your career path with growing job demand.

  Read the article

• A few things I learned regarding Azure billing policies

  - by Vincent Grondin

  An hour of small computing time: 0,12$ per hour A Gig of storage in the cloud: 0,15$ per hour 1 Gig of relational database using Azure SQL: 9,99$  per month A Visual Studio Professional with MSDN Premium account: 2500$ per year Winning an MSDN Professional account that comes preloaded with 750 free hours of Azure per month:  PRICELESS !!!      But was it really free???? Hmmm… Let’s see.....   Here's a few things I learned regarding Azure billing policies when I attended a promotional training at Microsoft last week...   1)  An instance deployed in the cloud really means whatever you upload in there... it doesn't matter if it's in STAGING OR PRODUCTION!!!!   Your MSDN account comes with 750 free hours of small computing time per month which should be enough hours per month for one instance of one application deployed in the cloud...  So we're cool, the application you run in the cloud doesn't cost you a penny....  BUT the one that's in staging is still consuming time!!!   So if you don’t want to end up having to pay 42$ at the end of the month on your credit card like this happened to a friend of mine, DELETE them staging applications once you’ve put them in production! This also applies to the instance count you can modify in the configuration file… So stop and think before you decide you want to spawn 50 of those hello world apps  .     2) If you have an MSDN account, then you have the promotional 750 hours of Azure credits per month and can use the Azure credits to explore the Cloud! But be aware, this promotion ends in 8 months (maybe more like 7 now) and then you will most likely go back to the standard 250 hours of Azure credits. If you do not delete your applications by then, you’ll get billed for the extra hours, believe me…   There is a switch that you can toggle and which will STOP your automatic enrollment after the promotion and prevent you from renewing the Azure Account automatically. Yes the default setting is to automatically renew your account and remember, you entered your credit card information in the registration process so, yes, you WILL be billed…  Go disable that ASAP    Log into your account, go to “Windows Azure Platform” then click the “Subscriptions” tab and on the right side, you’ll see a drop down with different “Actions” into it… Choose “Opt out of auto renew” and, NOW you’re safe…   Still, this is a great offer by Microsoft and I think everyone that has a chance should play a bit with Azure to get to know this technology a bit more...     Happy Cloud Computing All

  Read the article

• LLBLGen Pro feature highlights: model views

  - by FransBouma

  (This post is part of a series of posts about features of the LLBLGen Pro system) To be able to work with large(r) models, it's key you can view subsets of these models so you can have a better, more focused look at them. For example because you want to display how a subset of entities relate to one another in a different way than the list of entities. LLBLGen Pro offers this in the form of Model Views. Model Views are views on parts of the entity model of a project, and the subsets are displayed in a graphical way. Additionally, one can add documentation to a Model View. As Model Views are displaying parts of the model in a graphical way, they're easier to explain to people who aren't familiar with entity models, e.g. the stakeholders you're interviewing for your project. The documentation can then be used to communicate specifics of the elements on the model view to the developers who have to write the actual code. Below I've included an example. It's a model view on a subset of the entities of AdventureWorks. It displays several entities, their relationships (both relational and inheritance relationships) and also some specifics gathered from the interview with the stakeholder. As the information is inside the actual project the developer will work with, the information doesn't have to be converted back/from e.g .word documents or other intermediate formats, it's the same project. This makes sure there are less errors / misunderstandings. (of course you can hide the docked documentation pane or dock it to another corner). The Model View can contain entities which are placed in different groups. This makes it ideal to group entities together for close examination even though they're stored in different groups. The Model View is a first-class citizen of the code-generator. This means you can write templates which consume Model Views and generate code accordingly. E.g. you can write a template which generates a service per Model View and exposes the entities in the Model View as a single entity graph, fetched through a method. (This template isn't included in the LLBLGen Pro package, but it's easy to write it up yourself with the built-in template editor). Viewing an entity model in different ways is key to fully understand the entity model and Model Views help with that.

  Read the article

• Oracle ADF Core Functionality Now Available for Free - Presenting Oracle ADF Essentials

  - by Shay Shmeltzer

  Normal 0 false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:Arial;} We are happy to announce the new Oracle ADF Essentials - a free to develop and deploy version of the core technologies at the base of Oracle ADF – Oracle’s strategic development framework that was used, among other things, to build the new generation of the enterprise Oracle Fusion Applications. This release is aligned with the new Oracle JDeveloper 11.1.2.3 version that we released today. Oracle ADF Essentials enables developers to use the following free: Oracle ADF Faces Rich Client components –over 150 JSF 2.0 components that include extensive charting and data visualization components, supports skinning, internalization, accessibility and touch gestures and providing advanced Ajax, windowing, drag and drop and other UI capabilities in a declarative way. Oracle ADF Controller – an extension on top of the JSF controller providing complete process flow definition and enabling advanced reusability of flows inside page’s regions. Oracle ADF Binding – a declarative way to bind various business services to JSF user interfaces eliminating tedious managed-beans coding. Oracle ADF Business Components – a declarative layer for building Java based business services on top of relational databases. The main goal of Oracle ADF Essentials is to bring the benefits of Oracle ADF to a broader community of developers. If you are already using Oracle ADF, a key new functionality for you would be the ability to deploy your application on GlassFish. Several other interesting points: We provide instructions for deployment of Oracle ADF Essentials on GlassFish and officially support this platform for Oracle ADF Essentials deployment. Developers can choose to use the whole Oracle ADF Essentials, or just pieces of the technology. Visual development for Oracle ADF Essentials is provided in Oracle JDeveloper. Eclipse support via Oracle Enterprise for Eclipse (OEPE) is also planned. Want to learn more? Here is a quick overview and development demo of Oracle ADF Essentials For more visit the Oracle ADF Essentials page on OTN

  Read the article

• SQL Developer Data Modeler: On Notes, Comments, and Comments in RDBMS

  - by thatjeffsmith

  Ah the beautiful data model. They say a picture is worth a 1,000 words. And then we have our diagrams, how many words are they worth? Our friends from the Human Relations sample schema So our models describe how the data ‘works’ – whether that be at a logical-business level, or a technical-physical level. Developers like to say that their code is self-documenting. These would be very lazy or very bad (or both) developers. Models are the same way, you should document your models with comments and notes! I have 3 basic options: Comments Comments in RDBMS Notes So what’s the difference? Comments You’re describing the entity/table or attribute/column. This information will NOT be published in the database. It will only be available to the model, and hence, folks with access to the model. Table Comments (in the design only!) Comments in RDBMS You’re doing the same thing as above, but your words will be stored IN the data dictionary of the database. Oracle allows you to store comments on the table and column definitions. So your awesome documentation is going to be viewable to anyone with access to the database. RDBMS is an acronym for Relational Database Management System – of which Oracle is one of the first commercial examples If the DDL is produced and ran against a database, these comments WILL be stored in the data dictionary. Notes A place for you to add notes, maybe from a design meeting. Or maybe you’re using this as a to-do or requirements list. Basically it’s for anything that doesn’t literally describe the object at hand – that’s what the comments are for. I totally made these up. Now these are free text fields and you can put whatever you want here. Just make sure you put stuff here that’s worth reading. And it will live on…forever.

  Read the article

< Previous Page | 29 30 31 32 33 34 35 36 37 38 39 40  | Next Page >