One of South Africa`s major insurance companies, Hollard Insurance, can now see the big picture, thanks to their innovative use of sophisticated database design software.
In 1994, Hollard Insurance embarked on an ambitious project to develop a new Policy Administration and Claims Processing system.
"At the start of the project, all work related to the database was performed using tools supplied by the database vendor," says David Sieff of SPL-Chariot, the company that sells and supports the Logic Works suite of database products in South Africa.
"This proved highly problematic, as Hollard Insurance was unable to see the global picture. The company`s database is very large and the tools in use provided no means for a graphical display of its design. In addition, vital functions such as depicting relationships between tables, had to be done manually.
"They needed a tool to manage the development of the logical and physical databases." Hollard Insurance then installed ERwin, a leading database design tool for client/server, Web and data warehouse development by Logic Works.
"We have found ERwin to be a very intuitive tool to use. It has great help facilities, and allows a high level of customisation," says Neil Thomas, system architect at Hollard Insurance.
"We can now see the big picture," he says. "ERwin displays the underlying database tables and their relationships in graphical format. The tool overcomes the difficulties of getting to grips with our large database (some 800 tables) by means of its subject area feature. Using subject areas, we have sub-divided our model into groups of tables that are related by business or application. This allows developers to have a succinct picture of the tables involved in their areas of focus."
Erwin`s graphical display can be modified to use different colours and fonts, and to show different amounts of information. For example, users can choose to see the table name only or maximum information including table name, columns, primary keys, foreign keys and datatypes.
"Using ERwin, Hollard Insurance was able to set up default Referential Integrity (RI) rules for each relationship type," says Sieff. "These are enforced by triggers created by using built-in templates. The default templates provided were tailored to suit Hollard`s requirements."
"Other modeling tools that we evaluated failed to come close to ERwin`s support for trigger customisation," says Thomas. "ERwin allows the RI rule (and the associated template used to enforce this rule) to be overridden at the individual relationship level. In addition, one can add custom code to each table trigger without losing the flexibility of being able to change the `behaviour` of the underlying templates."
ERwin maintains both a logical and physical model of the database design. This allows one to design a logical model of the business without compromising for the chosen database platform. In addition, the names, definitions and comments attached to each attribute/column, entity/table and their relationships can differ between the two models. All of this information can be readily extracted through a variety of customisable reports.
Erwin`s reverse engineering facility is highly flexible and quick. Developers can select which database objects are to be included in a model during a reverse engineering task. In addition, one can reverse engineer from a script file that contains a full or partial schema definition. One can also sync an existing model to an existing database with the same degree of object selectivity.
Forward Engineering (FE) provides the ability to setup customised profiles of which objects are to be created. In addition one can filter which entities of the subject area in question are to be included in the FE task. This can take the form of a script file creation, printed report, preview or generation directly to the database. Specifically in regard to Microsoft SQL Server, schemas can be generated using older or more recent ANSI DDL standards.
Model Mart, a related Logic Works product also in use at Hollard Insurance, carries the benefits of ERwin modeling into the multi-user environment. In this environment, one can define a variety of corporate standards such as RI rules, trigger templates, defaults, constraints and domains, across all models in the same library.
Model users are assigned user profiles, which can be customised, based on the tasks they can perform. For example, at the one end of the scale you have the all powerful administrator, and at the other end, the read-only viewer.
With many analysts working on the same model, conflicts can arise when the models need to be merged. ERwin provides conflict management facilities together with merging and versioning. One can extract a snapshot of a subject area, take the model off site, work on the model and then return it to the repository.
"Having all models located in a central repository makes it far easier to backup or restore," concludes Sieff.
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