SQL

Good day all, I am looking at the Magritte/Pier "bible" (Reng06a.pdf) Sec 2.3.2 (page 8) Object Relational Mapping. I decided I would take a stab at implementing: "In a very similar way, we are able to automatically create SQL statements to store, load and query objects from a relational database". Any one care to offer hints? I am very much a novice at all these patterns and things, so I am guessing a Visitor pattern of sorts (I HAVE been studying the Gang of Four bible tho ;).... Here is what I have so far: MADescription: added methods: defaultSqlWriter. class>>defaultSqlWriter ^SQLWriter And I have created MAWriter subclass SQLWriter with one instance variable 'sql' SQLWriter>>defaultWriteStream ^((sql isNil ifTrue: [ sql := String new]) writeStream). SQLWriter>>write: anObject description: aDescription to: aStream anObject isNil ifTrue: [ ^ aDescription undefined ]. ^ super write: anObject description: aDescription to: aStream which, looking at it now, I really shouldn't need to override Then there are the visiting method which are going to be the reall tricky part. SQLWriter>>visitContainer: aDescription aDescription memento model isNil "we have a NEW model object so INSERT" will this work????? heh ifTrue: [ stream nextPutAll: 'INSERT INTO '; nextPutAll: aDescription table; nextPutAll: ' VALUES ('; cr ] where does the table method come in? hmmm ifFalse: [ stream nextPutAll: 'UPDATE '; nextPutAll aDescription table; cr; nextPutAll: 'SET ' ]. And then I will need to add something like: aDescription do: [ :desc | self write: something description: desc stream: stream ] What something goes here I am still scratching my head about... Any help/suggetions with this last part would be greatly appreciated. Also, I have started to get used to looking at the unit tests to figure out what things are supposed to do, then I noticed that there are NO tests for MAVisitor and subclasses. Why is that? (Or am I missing something?) Thanks in advance for any advice John McKeon