Modeling relational databases

  • Hi,

    At the company we are being Audited by some entity...

    This entity is asking for the ERD Model of each database.

    When we develop the databases we do it directly in relational form, not first in ERD model and only then pass it to relational.

    What are you guys doing?

    Do you use ERD model first?

    Is it wrong no to have a ERD model of each database?

    We just have the SQL Server Diagram of each DB.

    Can you please help?

    What are you using to model and to present your relational database models to clients?

  • When I started here the first thing I did was model the DB, as one did not exist. Fortunately we have Visio 2007, and I was able to reverse engineer the DB. That atleast got the tables and views for me. And it made our auditors happy when they came thru.

    ERWin is probably the class of the field, but it can be expensive.

    Regarding development process, it's a coin flip. A small shop can get away with creating the objects as you go. but once more than 3 people have to develop in the DB, a model is worth its weight in gold. Easy reference when writing queries because your relationships are visible. And when new objects are created it allows the entire team to know what to expect. My preference? Model 1st.

    Just my .02 worth. 😀


    Greg Roberts

  • Database models are useful even if you work in a small shop. And not only for auditing purposes 🙂

  • Do you guys use Erwin to model? or other tool? or make every think in paper (work, etc..) and pas it to visio?

    My question is, do you have help from a modeling tool like Erwin? or do you make by your own?

  • MS Visio

  • does Erwin help people that have some difficulties in modeling? Does it point you in the right way when you do mistakes?

  • you say that you model and then pass it to visio.

    Do you make the ERD model?

  • I reverse engineered the database using Visio's built in tools. Then as changes are developed they are first added to the model.


    Greg Roberts

  • The auditing entity is asking for an ERD, or Entity Relationship Diagram. In database modeling terms, an ERD represents a Conceptual Model (this is the highest level in a three-level 'schema architecture', followed by a Logical Model and lastly by a Physical Model). Sql Server and other RDBMS's have a "Relationship" feature which can reverse engineer the database into its Physical database model, but this can usually suffice as both the Logical Model and the conceptual ERD. At the Concept Model level, "Entities" represent the database tables and "Attributes" represent columns in a Logical Model. ERDs allow naming the tables and columns with friendly names (e.g., "Last Name" instead of "LName", "Customer" instead of "tblCUST", etc.). The best database modeling tool, in my professional opinion, is Embarcadero's ER/Studio. Better (and less expensive) than ER/Win.

    You should probably send the auditors your Sql Server Relationship Diagram: that should suffice.

  • I think ERStudio from Embarcadero is WAY better for SQL Server modelling. Much better pricing too.

    But for what this OP needs, I would just slap something together for the auditors using Visio if you have it or even the modelling tool from within SSMS. No need to pay money for nebulous external requirements.

    I DO think it is valuable to have a good ERD and good ERD tool, however!!

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • I have used a free ERD diagramming tool recommended by my professor in grad school, called DIA.

    Good for conceptual model. (and free) and UML

    https://live.gnome.org/Dia/Download

  • I have not used it but did see a short demo of ERStudio from Embarcadero when looking for tools for a migration project. It could do what I needed at the time, but for pure modelling it looks VERY compelling and easy enough to generate the ERDs.

    Joie Andrew
    "Since 1982"

  • +1

  • Visual Studio now has some great tools where you can build a database. It will treat it more like "code" and also you can run the project through an MSBuild process and it will deploy difs for you automatically.

  • In software engineering, data modeling is the process of creating a data model for an information system. This is done by applying formal data modeling techniques.
    There are many tools which can help you with modeling. Some of them are free, some of them aren't. I will list you few of them which I've found most useful. 

    SQLDbm

    SQLDBM offers you an easy, convenient way to design your database absolutely anywhere on any browser, working away without need for any extra database engine or database modelling tools or apps. Use SQLDBM to design and manage both large and small databases and data models on the fly. All while incorporating any needed database rules and objects such as database keys, schemas, indexes, column constraints and relationships.

    Price: Free

    PowerDesigner

    PowerDesigner is arguably the industry’s leading data modelling tool. Its features include: fully integrated models, different modelling techniques that cater to both an IT-centric audience and non IT-centric. It also supports a powerful metadata repository and various output formats. It has a nice and polished user interface with easily readable help documentation aiding the user to quickly solve ad hoc problems.

    Price: $2,000

    ER/Studio

    ER/Studio is an intuitive data modelling tool that supports single and multi-platform environments, with native integration for big data platforms such as – MongoDB and Hadoop Hive. It can forward and reverse engineer models, includes a compare and merge function and is able to create reports in various formats (XML, PNG, JPEG). Built-in features automate routine tasks and supports the popular database platforms. ER/Studio is a great tool that that is easy to start working with due to its intuitive design and good user support.

    Price: $1,500 up to $7,500

    It truly depends on you. To design, or redesign, a database of any complexity, the Entity-Relationship modelling tool becomes essential. The specialized tools that have dominated the industry for a long while are expensive and are installed on a workstation.

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