About Clarion

Delivering Code Reusability for Developer Productivity

Specialized Tools and Behaviors for Database Developers

Rich Language, Compilers, Tools for Other Platforms

Development Environment Tools

Building a Clarion Data Dictionary

Referential Integrity, Validity Checks, Concurrency Checks, Hot Fields, etc.

Template Metabase

Application Wizards

Structural Flow Chart

Built-In Reporting
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Clarion 6

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Referential Integrity, Validity Checks, Concurrency Checks, Hot Fields

Clarion applications can optionally maintain referential integrity in the client application. Clarion allows for the ability of a developer working with a PC flat file database, such as Btrieve files to provide DBMS type relational stability to a standalone application. This is also useful for developers working with DBMS's, but who wish the front end application to perform these tasks in order to reduce network traffic. The latter is of prime importance to developers deploying applications over the web or IP-based WANs.

Clarion allows developers to set RI options in the Data Dictionary. An add-in for Clarion, standard in Enterprise Edition, is the Data Modeler. This provides a graphical interface for managing the database schema and business rules, as illustrated below:

Validity checks, along with referential integrity, are the other of the two items that describe the "business rules" of a database. These may be as straightforward as "commission must be less than 10%", or can contain complex formulae. Clarion's Data Dictionary can store a number of validity check options (see below), which can then be automatically implemented in the generated code, and the development environment allows for easy implementations (through items such as the formula editor and embedded code points) for more complex ones.

Concurrency checks govern the rules of what to do if an end user makes an edit, and then when asking the database to save it, suddenly finds another user has made a change to the record between the time the end user first opened it, and the time the end user decided to save it. Clarion applications are automatically multi-user aware.

The previous items are usually treated by other development tools as something to be left to the DBMS. Hot fields are an item which belong in the front end, and are often created, at great costs in time and effort, by individual developers using other tools, because other tools don't include this features. This is the ability of the browse box (data grid) to be given an option to "be aware" of another (Detail) browse box, and to "limit" its contents according to the selected record in the other (Master) browse box. In effect, this "synchronizes" the two grids so that if the end user selects the parent in one table, the child records can appear in the other.


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