mapping relational database schema to document type definition (DTD)

Question

Is it possible to map relational database schema to document type definition (DTD) Then start Populating an XML document. I have been given something like the following:

Division(A, B, C, D) and other 4 more relations (tables)

I know that if I have xml then I can make the DTD, but in this case the relational database schema has been given. The question was:

"Design a proper DTD for the information given by the above relational database schema. The valid XML documents under this DTD must have a tree structure with as much nesting as possible. The DTD must also capture all the primary key and foreign key constraints."

I am not looking for pure direct answer, but I really want to understand if I can make DTD from the 4 given relations (tables). If it is possible, are there any steps that I need to know.

I have tried to do the xml but the instruction given ask to make the DTD first then populate an xml file.

Answer 1

The way the requirement has been expressed indicates that the XML should represent relationships using the XML tree structure where possible, or ID/IDREF relationships otherwise. I think that to get this right, you need to reverse-engineer an entity-relationship model from the SQL database schema, and then find an XML representation of that entity-relationship model - which will involve deciding which relationships to model using XML containment and which to model using ID/IDREF foreign keys.

Good luck: it's an interesting assignment.

You say:

I have tried to do the xml but the instruction given ask to make the DTD first then populate an xml file.

I would never try to write a DTD without first producing a representative XML document to test it against.