Frequently asked questions

DB-MAIN requests a serial number on startup when the license file does not exist (first run) or when the license is no longer valid.

If, after the introduction of number, the OK button does not work, it means that the license number is incorrect.
Solution: Make sure you enter a license number compatible with the version of DB-MAIN. If you try to introduce a license number version 9 with DB-MAIN 8, it will not work. In this case, you must download the new version and use the license number sent automatically. If the license number is compatible with the version, check it has been properly introduced. If the problem persists, contact dbm@rever.eu.

If, after the introduction of number, the message [Your DB-MAIN license has expired. You can renew it on www.db-main.eu (menu Support).] appears, it means that the validity date of the license number is exceeded.
Solution: Renew your license number by going to the Support section of the website.

If, after the introduction of number, the message [Impossible to generate the DB_MAIN.LIC file. Check that you have write permissions on the DB-MAIN setup directory.] appears, it means that DB-MAIN does not have permissions to write the license file in its setup directory. This problem appears especially on Windows Vista and Windows 7.
Solution: Run DB-MAIN as administrator (right click on the shortcut DB-MAIN and select Run as administrator). Next starts, run DB-MAIN normally.

There is a sixty-minute FirstStep tutorial to help you get acquainted with database design and DB-MAIN manipulation. This short tutorial is included in the 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).

If 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.

You 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.

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.
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=).

You are using version 5.* or lower under Windows 2000. You should be using version 9 or higher.

When 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 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.

These questions are about projects developed in versions 1 to 3 of DB-MAIN. New concepts have been added to subsequent versions and 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 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".

DB-MAIN is upward compatible. This means that any project developed in version X can be imported by version Y with Y >=X. 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.

Some strings may be so long that they stretch out of their box when they are imported into selected documents. DB-MAIN draws the selected objects on the clipboard rather than on screen. Box sizes are calculated to surround the longest string on the screen. When the string is pasted into another medium (a Word document for example), Windows may impose different parameters, so that some strings appear shorter or longer than they do on screen and extend beyond the limits of the box.
Solution: Select the box in the Word document and stretch it horizontally until it covers all the strings. NB: there is no relation between how the schema looks in a DB-MAIN window (always correct), in a Word document and on paper. We would welcome any elegant workarounds.
The problem may be encountered with selected reduction factors only. Always identify the reduce factors that give the best results on your installation and use them consistently.

An uncommon but annoying problem that may affect some graphic cards (e.g. ASUS-MEW V2.1 released in 1999) is that the length of an entity type box is a little smaller than the lines that define the various compartments (Name, Attribute, Group, etc). This may result in unattractive drawings in a Word document for example. This is a graphic card driver problem. Other software exhibits GUI problems too.
Solutions: You need a more recent card driver. In the Word document, double-click on the schema, then close it.

The graphical space of DB-MAIN is very large, covering several square kilometres with a resolution of 1 micro-metre. In Windows the window covers only about 64 square metres. 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-metre 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 centre of the schema.

DB-MAIN uses an intelligent algorithm to refresh the graphical representation of schemas. Only those objects that intersect with the visible window are redrawn. This is one of the reasons why DB-MAIN is so fast. Drawing the arcs is a more complex process. An arc linking two invisible objects may traverse the screen, in which case it is visible, and must be redrawn. Identifying the arcs that traverse 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 to large graphs.
Solution: Use the hypertext representation instead. It is fast, readable and easier to use.