4GL Errors and Consequences

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Further requirements

1. Remove the cross platform requirements for the DBMS provider from the language. Cross platform capability should exist in the DBMS itself. From the user and programmer point of view the whole database should appear as a single logical database regardless of how it may be separated physically or over DBMSs from different providers.

2. Constraint driven rather than event driven. In any given context the user can do anything that is allowed by the business rules (and nothing else). Event driven is a nice to have really, if you have a constraint that states that you can't delete a row in a table until you have recorded its final state in a historical table then it is quite useful to have an event that will do this for you automatically - but not essential. Otherwise if the database has been properly designed event processing is only occasionally useful.

3. The database is "aware of" all programs that use it. This means that changing the type of any variable (remember "tables" are relation variables) in the database will automatically force recompilation of any programs that use this variable and (for example) deleted columns will automatically disappear from all screens that use them.

4. As a follow on from point 3 drop the idea of a host language altogether. Codd was a brilliant man but the idea of a data "sub-language" was a mistake, I think. This way we can perhaps get away from the commonly held misapprehension that "tables" are a storage medium like files (and are therefore "created") but are actually relation variables (and are therefore declared).

5. No cursors and no dumping of relations into iterative structures like arrays (or XML).

As a further point I'm not especially keen on the term "4GL". Also it is often hard to separate you functional requirements from your cross platform requirements. Also drop the CRUD please, to reiterate you don't create or read things in an RDBMS and the terminology leads directly to the kind of misguided thinking detailed in point 4 above. You don't create records in a table, you update the value of a relation variable (with the relational operator union).

Posted by: jorwell   Posted on: 09/28/06 You are currently: a Guest | Members login | Terms of Use

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