DB-Main

Database Modellering en Architectuur

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Moeten uw informatiesystemen worden gemodelleerd?
Vereenvoudig uw engineeringtaken met DB-Main

Rever DB-Main is een gebruiksvriendelijk platform voor data modellering en data architectuur. Deze software omvat ook een toolbox dat de engineering van informatiesystemen ondersteunt. DB-Main helpt ontwikkelaars en analisten bij het merendeel van hun dagelijkse werkzaamheden. De toepassing heeft betrekking op alle data engineeringprocessen en maakt de volgende activiteiten gemakkelijker uitvoerbaar:

  • Ontwerpprocessen
  • Transformaties
  • Reverse engineering en programma-inzicht
  • Onderhoud, evolutie en integratie

Daarnaast omvat de Rever DB-Main software ook meta-modeleringscomponenten waarmee u nieuwe functies kunt ontwikkelen en de gegevensbank verder uitbreiden. En dat is niet alles, want de software bevat nog tal van andere functionaliteiten die u in staat stellen om uw projecten te ontwikkelen zoals u het wilt.

Met Rever DB-Main kunt u informatie op verschillende abstractieniveaus verwerken. U kunt ze omvormen tot

  • Een conceptueel model
  • Een logisch model
  • Een fysiek model

Applicatieontwikkelaars werken meestal met logische modellen, terwijl databasebeheerders liever aan de slag gaan met fysieke modellen. De Rever DB-Main software is in beide gevallen dé tool bij uitstek.

Onze software heeft wereldwijd meer dan vijftienduizend gebruikers en speelt al jarenlang een toonaangevende rol binnen de internationale academische en researchgemeenschap. De toepassing wordt op grote schaal gebruikt voor onderzoek en database engineering, en helpt studenten en professoren al meer dan 20 jaar bij hun onderzoek.

Exclusief programma voor de academische wereld

Wij hebben een lange geschiedenis van samenwerking met de academische gemeenschap. Van toen onze software voor het eerst werd uitgebracht, vertrouwen enkele honderden universiteiten over de hele wereld op Rever DB-Main.

Rever DB-Main wordt veel gebruikt door IT-scholen in België, Italië, Brazilië, Spanje, Frankrijk, Duitsland, Zwitserland en Vietnam, om er maar een paar te noemen. Onze software wordt gebruikt voor onderzoek en database engineering.

Individuele academische licentie

Wij willen onze trouwe gebruikers uit de academische wereld (zowel studenten als academisch personeel) bedanken voor hun langdurige ondersteuning van Rever DB-Main en bieden hen daarom een speciale licentie met korting aan voor ons datamodelleringsplatform.

Koop uw DB-Main academische licentie

Groepslicenties op maat

Wij bieden ook groepslicenties aan scholen, hogescholen en universiteiten. Neem vandaag nog contact met ons op voor een vrijblijvende offerte op maat van uw behoeften.

Contacteer ons voor een groepslicentie

Alles wat u nodig hebt voor
data modellering en engineering van informatiesystemen

1. Een modelleringskader

De Rever DB-Main software biedt krachtige componenten die u zelden tegenkomt in standaard data modelleringstools. Hier volgt een overzicht van de belangrijkste kenmerken:

  • Geschikt voor alle modellen
  • Verschillende wizards beschikbaar in de tool
  • Niet zomaar een “draw-and-generate” tool
  • Reverse engineering
  • Geschikt voor alle methodes
  • Programmeerbaar en uitbreidbaar
  • Korte foutdetectie- en herstelcyclus

2. Een ontwikkelingsomgeving voor modelleringstools

De Rever DB-Main software maakt de ontwikkeling mogelijk van gespecialiseerde modelleringstools, ofwel door gebruikmaking van specifieke methodologieën, ofwel door toevoeging van nieuwe concepten en functionaliteiten aan het basispakket. Er zijn drie manieren om gepersonaliseerde modelleringstools op te bouwen:

  • Functionele uitbreiding: de ingenieur – analist of methode ingenieur – krijgt een JIDBM-bibliotheek voorgesteld waarmee hij nieuwe functies kan ontwikkelen die naadloos in de tool worden geïntegreerd. Zo kan hij specifieke rapporten of code generatoren, tekstanalysatoren (bijvoorbeeld voor het importeren van woorden), complexe transformaties of specifieke controles voor specifieke problemen en gebruikscontexten opbouwen. De JIDBM-bibliotheek is en Java Interface speciaal ontwikkeld voor de Rever DB-Main toepassing en kan worden gebruikt voor de ontwikkeling van Java plug-ins. Deze bibliotheek geeft de gebruiker toegang tot de DB-Main gegevensbank in zowel lees- als schrijfmodus, en heeft zelf toegang tot alle menu-onderdelen van de DB-Main software.
  • Uitbreiding van de repository: de repository is geïmplementeerd als een object-gebaseerde opslagplaats waarin de tool de gebruikte methodologie, de projecthistoriek en de productspecificaties, hoofdzakelijk schema’s en teksten, registreert. Nieuwe eigenschappen kunnen dynamisch worden toegevoegd en beheerd via Java-functies.
  • Customisatie van de methodologieën: dankzij de architecturale basisprincipes die aan de grondslag liggen van de tool (zoals generieke specificatiemodellen, transformatie-operatoren, toolkit architectuur), is deze geschikt voor alle methodologieën en kan de software de analist helpen bij het gebruik van een grote verscheidenheid aan methodologieën. Deze customisatie is nuttig voor gebruikersbegeleiding, maar biedt vooral een nauwkeurige en gestructureerde manier voor het bijhouden van engineering historieken die noodzakelijk zijn voor de controle van de onderhouds- en evolutiesystemen.

3. Een toolbox dat de engineering van informatiesystemen ondersteunt

De Rever DB-Main software biedt een krachtige ondersteuning van de meeste forward en reverse engineering activiteiten. De tool omvat meer bepaald de volgende functies en componenten:

  • Specificatiebeheer: toegang, navigatie, aanmaak, actualisering, kopiëren, analyse, geheugenopslag.
  • Weergave van de projecthistoriek alsook van de producten (schema’s, bronteksten, gegenereerde programma’s) en van de processen die de producten of beslissingen gebruiken of genereren.
  • Een generiek, zeer verscheiden model voor de weergave van conceptuele, logische en fysieke objecten.
  • Een generiek model dat een beschrijving geeft van de procestechnische componenten van informatiesystemen op verschillende abstractieniveaus, alsook van de relaties tussen die componenten.
  • Semantische en technische semi-formele aantekeningen die aan ieder specificatie-object zijn aangehecht.
  • Meerdere weergaves van de specificaties (4 hyperteksten en 3 grafische weergaves); sommige weergaven zijn speciaal bedoeld voor zeer uitgebreide schema’s.
  • Een toolbox met meer dan 25 semantiek behoudende transformationele operatoren die gericht zijn op het systematisch uitvoeren van activiteiten zoals conceptuele normalisatie, of het ontwikkelen van geoptimaliseerde logische en fysieke schema’s voor conceptuele schema’s, en omgekeerd (d.i. reverse engineering).
  • Codegeneratoren (met inbegrip van een geavanceerde SQL-generator); rapportgeneratoren.
  • Code-parsers die fysieke schema’s ophalen uit SQL-, COBOL-, CODASYL-, IMS-, RPG-bronprogramma’s en XML-documenten.
  • Interactieve en programmeerbare brontekstanalysators die onder meer kunnen worden gebruikt voor het opsporen van complexe programmeringspatronen of clichés in bronteksten, alsook voor het opbouwen van gegevensstoomdiagrammen via programmavariabelen.
  • Een geavanceerde naamprocessor die de namen van geselecteerde objecten binnen een schema opkuist, normaliseert, converteert en vertaalt.
  • Een methode machine die gebruikers helpt bij het opvolgen van de engineeringmethodes, de historiek van de engineering activiteiten bijhoudt en de verdere automatische of geassisteerde replay ervan mogelijk maakt.
  • Het importeren en exporteren van specificaties in XML-formaat.
  • Een reeks wizards: een wizard is een soort van expert in een specifieke taak. Hij biedt ook de omgeving voor de ontwikkeling van scripts die op hun beurt fragmenten van het proces automatiseren. De tool omvat een bibliotheek met voorgedefinieerde scripts voor de meest voorkomende activiteiten, en zes steeds beschikbare wizards (eenvoudige algemene transformatie, geavanceerde algemene transformatie, schema-analyse, tekstanalyse, verwijzende sleutel).

Opmerking: de Rever DB-Main software werd ontwikkeld in C++. De software wordt op grote schaal gebruikt door industriële partners gespecialiseerd in systeemontwikkeling, maar ook voor reverse engineering, herdocumentatie, reengineering en migratieprojecten.

Documentatie

Datasheet

Tutorials (EN)

Andere tutorials

Deze 3 documenten (in het Engels) zijn louter informatief. Ze kunnen op bepaalde punten dan ook afwijken van de meest recente versie van de software.

Release notes

Readme file

FAQ (EN)

1. Getting Help

1.1. Questions referring to the software
  • Click to expand the list
      • If Rever DB-Main denies your licence number :Rever DB-Main requests a serial number on startup when the licence file does not exist or when the licence is no longer valid.

        To enter the serial number, click « Enter license » and type the licence number in the « Enter your license number » field. If, after the introduction of a serial number, the « OK » button does not work, it means that the licence number is incorrect.

        Solution : Make sure you enter a licence number which is compatible with the latest version of Rever DB-Main. Please use the licence number sent automatically to you by email. If the licence number is compatible with the version, check that it has been properly introduced. If the problem persists, please contact us.

        If, after the introduction of your number, the message [Your license has expired. Please upgrade your license to keep using DB-Main (revershop.rever.eu)] appears, it means that the validity date of the licence number is exceeded.

        Solution : Renew your licence number by visiting the Rever webshop.

        If, after the introduction of the number, the message [Impossible to generate the DB_MAIN.LIC file. Check that you have write permissions on the Rever DB-Main setup directory.] appears, it means that Rever DB-Main does not have permissions to write the licence file in its setup directory. This problem appears especially on Windows Vista and Windows 7.

        Solution : Run Rever DB-Main as administrator (right click on the shortcut DB-MAIN and select Run as administrator). At the next launch, run Rever DB-Main normally.

      • How do I use Rever DB-Main ?IMPORTANT for Windows Vista and Windows 7 users : At first start, run Rever DB-Main as administrator (right click on the shortcut DB-MAIN and select Run as administrator) to allow the licence file writing. Next time, run Rever DB-Main normally.

        There is a sixty-minute FirstStep tutorial to help you get acquainted with database design and Rever DB-Main manipulation. This short tutorial is included in the Rever DB-Main release (1st-step.hlp). It can be accessed from the welcome box when you start the tool or run it independently.

        Expand your knowledge with the extended Introduction to Database Design (300 pages). Follow the twelve lessons and work through the exercises.

        For more in-depth learning on database modelling, read the first volume in the Computer-aided Database Engineering (400 pages).

      • Rever DB-Main cannot open an existing projectRever DB-Main is upward compatible. This means that any project developed in version X can be imported by version Y with Y >=X. Rever DB-Main is not downward compatible however, because the repository is extended.

        Solution : Use the correct version. Also try to generate an ISL project (File/Save as in *.ISL or *.XML format), which is more version-insensitive (provided no method was used).

        The project may be corrupted. You can send us your project and we will try to salvage it.

      • Rever DB-Main asks me questions when I open selected projectsThese questions are about projects developed in versions 1 to 3 of Rever DB-Main. New concepts have been added to subsequent versions and Rever DB-Main is trying to upgrade these projects. Your project will never be corrupted, no matter what answer you give.

        First question : “Convert the parameters in the descriptions into dynamic properties?”

        Explanation : There are two ways to add meta-properties in Rever DB-Main (see Tutorials and Reference Manuals): the old-style semi-formal parameters (the “#property=value#” sentences in SEM or TECH annotations) and the more formal dynamic properties (visible in PROP). This question asks whether you want to convert the semi-formal parameters into dynamic properties. It is perfectly safe to answer ‘Yes’. This will preserve some interesting schema properties.

        Second question : “Convert connections into processes?”

        Explanation : In earlier versions, schemas and other products were independent, and arrows (connections) between them simply indicated informal dependency relations. In more recent versions the relations between products have been precisely defined by certain processes (a process uses products to build other products). This question asks you whether you want to convert the informal relations into (fictional) processes. It is perfectly safe to answer “Yes”.

      • What’s the difference between the licence key and the licence file ?After downloading Rever DB-Main, you’ll automatically get an email with your licence key. During installation, you’ll be asked to enter this licence key in a pop-up window. This licence key activates the software for 30 days.

        Once this period has expired, you’ll need a licence file to continue using Rever DB-Main. Click on GET LICENSE in the pop-up window to buy your 1-year licence in the Rever webshop. Once your order is completed, you’ll automatically get an email with your new licence key. Follow the instructions in the email to download the licence file and then be able to upload this file into DB-Main.

      • Why do you charge a small contribution for Rever DB-Main ?Rever had to extend its team to be able to support the 190,000 DB-Main users worldwide. Our new development plan will result in entirely new versions of Rever DB-Main with modern interfaces and many new features.

        These investments have a cost. That’s why we charge a small contribution set at €5/month ex VAT (€60 yearly ex VAT).

        If you are a student or IT school representative and wish to use Rever DB-Main, please note that we also offer an academic program to best fit your needs. The academic program comes with technical support.

      • Can I get group licences for Rever DB-Main ?Yes, Rever offers the possibility to large organizations, universities and colleges to get group licences at a reduced rate. Contact us for a proposal based on your specific needs.

      • What should University of Namur users do to download Rever DB-Main ?A special academic licence is available for users of the University of Namur. Make sure to use your @unamur.be email address on the download form and to select UNamur in the use drop-down list.

      • Missing libraries on WindowsRever DB-Main requests specific Visual Studio libraries. Some errors can appear such as :
        The program can't start because api-ms-win-crt-stdio-l1-1-0.dll is missing from your computer. Try reinstalling the program to fix this problem.

        Solution: Proceed as follows :

        • Install Windows Updates
        • Go to Start – Control Panel – Windows Update
        • Check for updates
        • Install all available updates
        • After the updates are installed, restart your computer
        • After the restart, repeat the steps above again until no more updates are available.

        If the problem persists

        • Download the Visual C++ Redistributable :
        • For Windows 64-bit : Visual C++ Redistributable for Visual Studio 2015 (64-bit).
        • For Windows 32-bit : Visual C++ Redistributable for Visual Studio 2015 (32-bit).
        • Run the vcredist_x64.exe (64-bit) or vcredist_x86.exe (32-bit) and select “Uninstall”.
        • Run the .exe again and select “Install and restart the computer”.

      • Installation problem on CentosIf you try to install Rever DB-Main on Centos 6.0 / i386, in VMWare Fusion 4 (fresh install), you may encounter a problem to launch Rever DB-Main, libtiff is missing.
        db_main: error while loading shared libraries: libtiff.so.4: cannot open shared object file: No such file or directory

        Solution : You can try to locate the libtiff library on Centeos : “locate libtiff.so”. If you find another version (e.g. libtiff.so.3), you can make a symbolic link with “sudo ln -s /usr/lib/libtiff.so.3 /usr/lib/libtiff.so.4” and retry Rever DB-Main.

1.2. Questions referring to the operating system
    • Mac – Why is MacOs not supported in V11 ?We are currently developing Rever DB-Main V11 for Mac.

      Meanwhile, you can continue to use an earlier version of Rever DB-Main. Contact us to get Rever DB-Main V9 for MacOS X.

    • Linux – Corrupted DB_MAIN.INI under LinuxYou may encounter this issue : under Linux, there’s no button available to draw anything (only the Zoom factor button and the Mark button).

      Solution : It seems to be a resource problem with Rever DB-Main. You can delete the DB_MAIN.ini file in your /home/username/.db_main directory and try again.

    • Linux – Library error on Rever DB-Main launch under LinuxThis is mainly to solve the problems of missing libraries to run the Linux version of Rever DB-Main.

      If you receive the following error on the screen :

      ./db_main: error while loading shared libraries: libwx_gtk2_core-x.y.so.0: cannot open shared object file: No such file or directory

      Solution : Make sure that you have updated the environment variable LD_LIBRARY_PATH

      The path to the Rever DB-Main bin directory must be there. In the readme.html file, we propose to update the environment variables like this :

      # Edit the .bashrc file (.profile in some environment) in the home directory
      						# and add the following lines (adapt the ~/db-main/bin directory to the one chosen previously):
      					export DB_MAIN_BIN=~/db-main/bin
      					export PATH=$DB_MAIN_BIN:$PATH
      					export LD_LIBRARY_PATH=$DB_MAIN_BIN:$DB_MAIN_BIN/../java/jre/lib/i386/client:$LD_LIBRARY_PATH

      If you receive another library error :

      Solution : Make sure that you have not tried to install a 32-bit version of Rever DB-Main under a Linux 64-bit (or vice versa). If this is the case, download the correct version in accordance with your operating system.

    • Linux – Compatibility problem between Linux and Windows LUN filesIf you use the Linux version of Rever DB-Main, you may experience compatibility problems to open a LUN file generated under the Windows version of our software.

      You do have the possibility to use LUN files simultaneously on Linux and Windows.

      Solution : First, be careful that LUN files are binary files. If you transfer these files by FTP, you must choose the binary option. Secondly, verify that Linux and Windows use the same encoding before using Rever DB-Main (by default Linux is UTF/8 and Windows CP1252). If it is not the case, you must change the LUN file encoding (some text editors have these functionalities).

2. Specifics

    • How to create an Access database from Rever DB-Main ?What is the procedure to create an Access database from a Rever DB-Main MPD ?

      Solution :

      • In Rever DB-Main, generate Access code on a relational schema (File/Generate/Access menu…).
      • Take the Access database (SQL-Interpreter.mdb) supplied with Rever DB-Main (for example in your directory C:\Program Files\DB-Main x.y.z\plugins\access\).
      • Run the “Execute SQL script” form.
      • Select the Access script generated by Rever DB-Main (“Find script”) and run the script (“Execute script”).
      • The Access database contains the MPD defined in Rever DB-Main.

    • How to get an MCD from a relational MLD/MPD ?Here’s how :

      Solution :

      • Open the MLD/MPD schema.
      • Make a copy of the schema (Product/Copy product… menu).
      • Open the copied schema.
      • Transform the schema into an MCD. To do this : – Run the Assist/Global transformation… menu. – Click the Predefined button. – Select the Relational rev. eng. input and click the Ok button.
      • Run the transformations. Click the Ok button.

    • How to obtain an MPD/MLD from a relational database ?Here are briefly described the three ways to recover the structure of a SQL database in Rever DB-Main :

      Solution :

      • Extraction of the DDL (SQL script) : – Prerequisite : to have a file containing the SQL statements for the construction of a database (CREATE TABLE, CREATE INDEX, ALTER TABLE, …). – Instructions :
        1. Start Rever DB-Main and create a new project (File/New project… menu).
        2. Run the SQL extractor (File/Extract/SQL… menu).
        3. Select the file to extract.
        4. A new schema is created. Double-click on it and you’ll see all the structures recovered by Rever DB-Main.

        Note : It may be that some statements are not recognized. Our extractor being generic (independent from technologies such as DB2, Oracle, SQL Server…), there may be some statements not taken into account (especially the technical parameters such as information storage). This is normally not a problem because they have no impact on the logical model of the database. Putting these statements in comment, it is possible to bypass the extraction problems.

      • ODBC extraction : – Prerequisite : to have on your machine the ODBC drivers allowing you access to the affected database types and to have set an ODBC data source. – Instructions :
        1. Start Rever DB-Main and create a new project (File/New project… menu).
        2. Run the ODBC extractor (File/Extract/ODBC… menu).
        3. Select the “Machine Data Source” tab. In the list, select a pre-defined source (Access, for example) or a source that you yourself created.
        4. Select your database. A dialog box asks you for a schema name. Fill the field if necessary (unnecessary with Access for example) and click OK.
        5. A new schema is created. Double-click on it and you’ll see all the structures recovered by Rever DB-Main.

        Note : It may be that some recovered system tables are not necessary. Just select them and delete them.

      • JDBC extraction : – Prerequisite : to have on your machine the Java JDBC drivers allowing you access to the affected database types and configure the environment variable CLASSPATH. – Instructions :
        1. Start Rever DB-Main and create a new project (File/New project… menu).
        2. Create a new schema (Product/New schema… menu).
        3. Run the JDBC extractor (File/Execute plug-in… menu). Open the file “JDBCExtraction.class” in the directory “plugins\jdbc” of the installation directory of Rever DB-Main.
        4. Select a DBMS (other, if you do not find your database type). Set the driver if necessary. Give the connection URL. Enter the username and password if necessary.
        5. A new schema is created. Double-click it and you’ll see the structures recovered by Rever DB-Main.

        Note : It may be that some recovered system tables are not necessary. Just select them and delete them.

        The JDBC extraction, when applicable, is the best solution to get a full MPD of your database.

    • How do I model a postGIS database with geometric types in Rever DB-Main ?Rever DB-Main is a generic data modelization tool. It is not specialised for specific databases like geographical databases. In this context, for example longitude and latitude are not standard attribute types in Rever DB-Main. But you can define your own specific types in user-defined properties.

      Solution : For example, select an attribute. In the property box panel (menu Windows/Property box if not shown), click on “User prop.” tab. On the line “physType”, you can give your own type (e.g. Latitude). You can also give a value like “latitude(%l)” where %l represents the attribute length defined in the “Prop” tab (%d for number of decimals).

      The SQL generators take into account the “physType” property if not empty. You can also develop your own postGIS generator (java plugin) by using the Java Interface for Rever DB-Main (See the file “SQLGenerator.java” in “plugins/sql” directory of your Rever DB-Main setup directory).

    • How to recover a MPD Access in Rever DB-Main ?If you want to recover through reverse engineering a MPD from a database established in Access with Rever DB-Main.

      Solution : Here’s how :

      • Start Rever DB-Main and create a new project (File/New project menu…).
      • Run the ODBC extractor (File/Extract/ODBC menu…).
      • Select the “Machine Data Source” tab. In the list, select “MS Access Database” and click OK.
      • Select your Access database. A dialog box asks for a schema name (which has no interest in the context of Access). Leave the field blank and click OK.
      • A new schema is created. Double-click it and you will see all the information retrieved by Rever DB-Main.

      It may be that some recovered system tables are not necessary (as MSysAccess…). Just select them and delete them.

    • • SQL code generation problem when creating your relational databaseWhen you try to generate the SQL script of your MCD via the [File/Generate] menu but the generated SQL script does not meet your needs (syntax problem, lack of information), what solution do you have ?

      Solution : We recommend you to use the Java plugins to create your own generator. To do this, you have a good base with the SQLGenerator.java program in the plugins/sql directory from the Rever DB-Main installation. You can use and transform this program to meet your needs.

3. Basics

    • How to add identifiers to association types ?To add identifiers to association types via the [New/Group] menu :

      Solution : You must select the attributes and/or roles of the association types which shall participate to the identifier, then click on the [New/Group] menu and select the “Identifier” function in the group’s property box (or simply click on the “Identifier” button on the standard toolbar). If this menu (or button) is grayed out, the selected objects cannot form an identifier group of the association types.

    • How to create hybrid identifiers ?There are commands to create an hybrid identifier (containing attributes and roles).

      Solution : In the LIBRARY schema (ABOUT dialog box, button [Demo project]), to create the hybrid identifier of COPY (of.BOOK, Copy-No), first select role [0-N] played by entity-type BOOK in relationship-type of and attribute Copy-No of COPY. After that, click on ID button in the standard toolbar to create the hybrid identifier.

    • How to create a nonstandard attribute for the generation of database creation scripts ?For example, if you want to create TEXT attributes (that is to say attributes that will have the TEXT type in a relational database), you can do it like this :

      Solution : To remedy to this type of problem, we set up a mechanism allowing generators ([File/Generate] menu) to take into account the physical types specific to a language (in our case, type TEXT). This mechanism consists in the updating of the user property “physType” (“User prop.” tab from the property box). The value set in this property will be taken into account for the generation (only if it exists, otherwise you take Rever DB-Main’s own type). This feature is available since version 9.1.1 of Rever DB-Main.

    • How to create a user defined domain (and subdomains) ?If you try to add a user defined domain to a project : how can it be decomposed while containing subdomains ?

      Solution : When you create your primary domain using the dialog box ([Product / User domain …] menu, [New] or [Modify] buttons), you have two buttons [First dom.] and [Next dom.]. The [Next dom.] button creates a user domain of the same level. On the other hand, the [First dom.] button creates a subdomain of the current domain. You can thus create decomposable user domains.

    • How to ask the user to enter data during execution of a Java plugin in Rever DB-Main ?The DBMConsole class allows to capture the output stream, but not to enter data. Here’s how to remedy this :

      Solution : You can use the following code to display a dialog box to enter data. The use of this box is simple. You give it the title, the question asked, the type of icon that you want to see appear and it returns the answer in a string.

      Exemple:

      Example : String response = JOptionPane.showInputDialog(null,
      "What is your name?",
      "Enter your name",
      JOptionPane.QUESTION_MESSAGE);

    • How to give a multiple cardinality [N,N] to an association type ?This possibility does not exist in the choice of the “cardinality” line from the property box. Indeed, Rever DB-Main does not accept N-N cardinality for a role as it considers that it is impossible to verify this constraint in a database. This would mean that each instance of a table playing a N-N role should have mandatory countless links with another table.

      Solution : To create an association many-to-many [N-N], just give the 0-N cardinality to both roles.

    • How to rename two or more relations with the same name ?For example, if you want to rename a relationship type using the same name : province has district – district has village. But you can’t write ‘has’ the second time :

      Solution : In Rever DB-Main, the relationship types (like entity types) must have a unique name in a schema. But you can use the pipe (‘|’) at the end of the names to ensure the unicity. You can rename relations ‘has|1’ between ‘province’ and ‘district’ and ‘has|2’ between ‘district’ and ‘village’. On the screen, you’ll see twice ‘has’. The pipe and characters after will not be displayed.

    • How to rearrange the attributes of my entities or associations ?If you want to move up/down an attribute in an entity type or association type.

      Solution : To reorder your attributes in an entity type or association type, simply select the attribute and press the up arrow key (or down) of the keypad while simultaneously holding down the ALT key. Your attribute will then move up (or down).

    • How to represent reflexive associations ?Here’s how you go about creating a reflexive association type in a graphic view.

      Solution : You must first create an association type ([New/Rel type] menu). Click where you want to create it. Press ESC to stop the “graphic design” mode. Then go to the [New/Role/Rel-type/Link] menu to create both roles. Click the association type, hold the button and release it on the entity concerned. Repeat the same operation for the second role. Press ESC to stop the “graphic design” mode. You now have a reflexive association type.

    • How to represent a weak entity in Rever DB-Main ?In order to represent an entity whose identifier is related to another entity :

      Solution : It is possible to represent a weak entity type in Rever DB-Main. For example, run Rever DB-Main and, in the About dialog box, click the Library (demo project) button. Open the LIBRARY/Conceptual schema by double-clicking it. In this schema, you see that the identifier of the entity type COPY comprises its Copy-No attribute and the distant role 0-N played by BOOK in association type of. In the case of COPY, we speak of weak entity.

      To create an identifier of a weak entity type, be sure to select the role of the strong entity and not the one played by the weak entity in the relationship between them. For your information, a role is the object that has a cardinality, which is the link between two entity types. Generally (in the case of binary association between two entity types), there are two roles (cardinalities) on a link. The cardinality of a role is the minimum and maximum number of times an instance of an entity type can be connected to the instances of the related entity types. In a schema Entity/Association, it may be 1-1, 0-N, 1-N, 4-5 (provided that the minimum cardinality is less than or equal to the maximum cardinality). In an UML class diagram, it will be 1, *, 1-*, 4-5.

    • Impossible to create attributes (grayed out in New menu) ?To create an attribute, it is necessary that the object for which you want to create it (entity type, association type or compound attribute) is selected.

      Solution : You must select an entity type, an association type or compound attribute and go to the [New/Attribute/First Att…] menu. If the [Attribute] menu is grayed out, it means that you are not in the correct view to see the created attributes (for example, the compact view). If you select the “View/Graph. standard” menu, you will see all the attributes that you have already created. Rever DB-Main has multiple views (textual or graphic) that can work on all schema types. The default view of a schema is the standard graphical view.

    • Does Rever DB-Main support ascending and descending legacy ?The descending and ascending legacy is not implemented in Rever DB-Main.

      Solution : You must achieve the transformation manually or write a Java module that will perform this transformation.

    • The graphical toolbar is invisible ?The toolbar is closed.

      Solution : Access this toolbar through Window/Graphical tools.

      The toolbar is open but has been moved beyond the limits of the screen./p>

      Solution : Increase the resolution of the screen to show the bar or edit the db_main.ini configuration file (“Windows” directory in version 8 and lower, “\Documents and Settings\xxx\Application Data\DB-Main” directory in version 9 and higher). In version 8 and lower, in [TOOL_POS], set GRAPH_X to 0 (GRAPH_X=0) and GRAPH_Y to 0 (GRAPH_Y=0). In version 9 or higher, in [Perspectives], set Layout to nothing (Layout=).

    • The configuration parameters do not workWhen you change the value of a parameter you must click the change button before you close the dialog box or the changes will not be saved.

      Exit and restart Rever DB-Main (some parameters are read at startup).

      Examine the contents of db_main.ini file (“Windows” directory in version 8 or lower, “Documents and Settings\xxx\Application Data\DB-Main” directory in version 9 or higher). This file records the current parameters.

4. Schemas

    • Want to use your schemas to illustrate a LaTeX report, in EPS or PDF format ?Solution : Rever DB-Main has no EPS/PDF output. To use graphical views in a document, you must select the elements of a schema that must be taken into account. Go to “Edit/Copy graphic” menu (or right-click of the mouse). Under Windows, the image is saved in the clipboard. Under Linux, it is saved in a BMP, PNG or JPEG file. To use the result in LaTeX, you’ll have to use an image conversion tool to EPS/PDF format.

    • Distant objects become inactive in large schemasThe graphical space of Rever DB-Main is very large, covering several square kilometers with a resolution of 1 micro-meter. In Windows the window covers only about 64 square meters. A particularly large schema can be obtained by reverse engineering, for example. In this case the entity types are displayed side by side, so that an 8 meter wide graph is relatively common. A graphical object that extends beyond the window may not be exhibited properly.

      Solution : Select a smaller zoom factor to bring the object back within the window. You can then move the distant objects towards the center of the schema.

    • Management of large schemasLarge projects are always difficult to manage. Large amounts of entity types are difficult to integrate into the main schema.

      Solution : We recommend that you develop each subsystem separately in a schema of the same Rever DB-Main project. When the subsystems are completed, we propose to integrate them (by copy/paste) in an integrated schema. This will allow you to create connections between subsystems. For your convenience, you can view your schemas in textual views (View/Text… menu). When working on large schemas, we use these views that were created for this purpose. These are hyperlinks that offer a range of interesting navigation functions. We recommend you to consult the Help section for more information.

    • The LUN file size increases abnormallyIf you find that, despite the few changes made to a project, the LUN file size increases abnormally. Maybe, willingly or not, you have activated the recording of all operations performed on a schema. This creates a log file (operation history) which is automatically saved in your LUN file.

      Solution : For all schemas, check that tracing is disabled (menu Log/Trace) and, if necessary, clear the log already registered (menu Log/Clear log). Before deleting the log, you can also save it in a different file (menu Log/Save log as…) in order to be replayed later (menu Log/Replay). To achieve the file cleaning, save your project.

    • Screen refreshing is slowed down in large schemasRever DB-Main uses an intelligent algorithm to refresh the graphical representation of schemas. Only the objects that intersect with the visible window are redrawn. This is one of the reasons why Rever DB-Main is so fast. Drawing the arcs is a more complex process. An arc linking two invisible objects may cross the screen, in which case it is visible and must be redrawn. Identifying the arcs that cross the screen is a time-consuming process, so we have decided to redraw all the arcs in the schema. A schema that includes 40,000 arcs – like some call graphs in very large applications – will clearly take more time to refresh. The problem is rarely critical for data schemas. If you experience a problem like this, the graph will probably be displayed as a solid black screen and it will be unreadable. This is a limitation of graphical representation: it works well with small graphs but is not suited for large graphs.

      Solution : Use the hypertext representation instead. It is fast, readable and easier to use.

    • Rever DB-Main refuses to create new objectsYou are in a view schema; view schemas have limited update capabilities.

      Solution : Work in the source schema instead.

      The tool is in History controlled mode and no process working on this schema is active (in other words, the schema is no longer updateable). In this mode, a product whose creation process has been closed cannot be updated or the chain of products would be rendered inconsistent. For instance, adding an attribute to a conceptual schema after its SQL code has been generated and compiled yields an inconsistent project

      Solution : Uncheck the Engineering/Control box. Be advised that project consistency checking will be lost.

    • Unique values for an attribute in an ER schemaHow to show that an attribute must contain unique values in an ER schema ?

      Solution : To show that an attribute must contain unique values in an ER schema, you must create an identifier containing this attribute. To create an identifier, select one or more attributes in a same entity type and click on the ID button in the standard toolbar.

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