ERWin Was A Fantastic Early MySQL Tool

erwinwafeLogicWorks Inc.’s ERwin/SQL is a Windows-based tool that lets database designers graphically create and maintain database structures. Database designs can be easily manipulated and are presented in a clear, flexible manner. However, ERwin/SQL’s complete absence of help and referential documentation made the product more difficult to learn and use than it should have been.

Rather than trying to be all database products to all users, LogicWorks’ ERwin/SQL 2.0 focuses on the all-important design of the database.

A heavy price can be paid for incorrectly designing a database — even if applications and data are correct, performance can be compromised. ERwin/SQL 2.0, which was released two weeks ago for $1,495, makes the process much smoother by allowing users to concentrate on the design of the database rather than on the Structured Query Language (SQL) syntax for implementing the structure, or “schema,” as it is known in database terminology.

With ERwin/SQL, users design the schema by creating separate entities and drawing the relationships between them. Both entities and relationships have characteristics, such as whether triggers are used on a relationship in the event of updates or deletions.

Drawing on knowledge of the fundamentals of database design and generating code to create databases, we had no trouble using ERwin/SQL. The product is not for novices, however — a user unfamiliar with these fundamentals will not learn them here.

To design a new database, we selected the entity icon on ERwin/SQL’s floating toolbox, then clicked on the screen where we wanted the entity to appear. We then selected the appropriate relationship icon on the toolbox and created relationships by clicking on the two involved entities.

Entering the details of the relationships and entities was easy, and ERwin/SQL provides a variety of ways to modify the entities. New in version 2.0 is the ability to use the right mouse button to click on an entity or relationship; this brings up a menu of all the editing methods for that object. These options are also available in the menus for keyboard users, but we found that using the right mouse button saves a lot of time.

The editors themselves provided fast access to the field names, or attributes, of the entities, as well as to logical names of entities and relationships. Some of the relationship attributes that were easily accessible were the foreign key that was used and whether nulls were allowed.

Once a schema was designed we simply chose the Database Schema option from the Report menu to begin generating SQL code to send to the database server. This option brought up a dialog box that allowed us to set certain options, such as whether implementation-specific facilities for referential integrity should be used.

The code itself can be sent to a window, to a file or to the printer. ERwin/SQL does not send the code to the server itself, but any administrator of such a database product would already have this capability or could copy the code out of the window and paste it to the tool.

ERwin/SQL supports a variety of implementation-specific features for various servers. Among the ones we tested were clustered indexes for Microsoft Corp.’s SQL Server; clustered indexes are also available for Sybase Inc., Gupta Technologies Inc. and Informix Software Inc. servers. In addition, we found that ERwin/SQL could use certain stored procedures in SQL Server. ERwin/SQL also supports DB2 and Oracle Corp., Ingres Corp. and Novell Inc. NetWare SQL database-management systems.

We were impressed with the variety of views that ERwin/SQL provides. For example, we were able to look at the names of the entities only, at the definitions that we had assigned to entities and at the keys for entities only. We also were able to shrink the objects to a half or quarter of their design size to get a “bigger picture” on the schema. In addition, ERwin/SQL gave us considerable control over whether logical names we had assigned to each object were displayed.

ERwin comes with a good tutorial, which is designed around a movie-rental application. The movie-rental model is a good choice, both because it is easy to relate to (at least for those who frequent video stores) and because it lends itself to a multitable representation. For example, there are many customers and many copies of movies, and a copy and a customer interact in a movie-rental record.

We were annoyed, however, that ERwin/SQL has no on-line help. LogicWorks officials said that ERwin/SQL is designed for database experts and that experienced users will quickly reach a point at which on-line help becomes superfluous.

PC Week Labs disagrees. We feel that all programs should include help for those features with which users are not intimately familiar.

Along with the testing we performed with Windows, we tested ERwin/SQL 2.0 on an OS/2 2.0 system on a NetWare network. Apart from the absence of TrueType fonts and some minor interface differences, ERwin/SQL worked as expected. For example, under Windows 3.1, when we right-clicked on an object, we were able to keep the mouse button down, drag through the pop-up menu to the desired option and release to select it. Under Win-OS/2 (and Windows 3.0), however, dragging did not work. We had to right-click on the object and then left-click on the desired menu item.

ERwin/SQL is a subset of a larger product, ERwin/ERX. The ERX product includes reverse-engineering capabilities that make it possible to import SQL statements for creating and describing tables and make an ERwin model from the statements. This feature can then be used to port the design to any other database server supported by either ERwin product.

We observed some minor bugs in testing ERwin/SQL. In one instance, ERwin generated a general protection fault and crashed, causing us to lose all our work since the last time we saved the model. On a few occasions, portions of a dialog box were not erased after it was closed. Minimizing and remaximizing ERwin/SQL caused it to redraw itself without the incorrect portions.

Testing Methodology

PC Week Labs tested ERwin/SQL 2.0 on a Dell Computer Corp. 450DE/2, a 50MHz 486 Extended Industry Standard Architecture (EISA) system with 8M bytes of RAM. Windows 3.1, under DOS 5.0, was run in VGA, standard Super VGA (800-by-600-pixel resolution) and with the ET4000 1,024-by-768-pixel, 16-color large font drivers.

ERwin/SQL was also tested less extensively on a Gateway 2000 Inc. 486/33C, a 33MHz 486 ISA system with 8M bytes of RAM, running Windows 3.1 under DOS 5.0. Windows was configured for the 8514/a driver with large fonts. We also tested the product on an IBM PS/2 Model P75 486, a 33MHz 486 system with 18M bytes of RAM running OS/2 2.0 using the XGA large font drivers and Novell’s NetWare Requester for OS/2 2.0.

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