Data structures and meaning
Logical relational schema
Tables and references at design level: keys, cardinalities and which table owns a fact — still no storage engine decisions.
ddn@1New DDN source
Why use it?
Move from business nouns to a checkable structure: every relationship now has a home and a direction.
When it helps
After the conceptual ER pass, before physical naming, indexing and platform choices.
How to read it
- Each box is a table; read keys first, then the reference arrows from foreign key to primary key.
- Crow's-foot marks state how many children a parent may have — claims, not constraints enforced here.
What you need
- The entity list from the conceptual model
- Candidate keys per table
- Ownership rules for every relationship
Things to check
- Do not put a foreign key on both sides.
- A many-to-many without a join table hides a missing entity.
Scope of this diagram
Logical only: datatypes, indexes and platform types are declared in the physical model, not here.
Work with the converted example
- Open the viewer and select
diagram. Inspect the rendered view and its source. - Open the designer. Keep the selected profile and inspect its legal palette and property controls.
- Change one displayed title or an appropriate data value. Apply the edit and check the resulting diagram.
- Run the verifier and review its diagnostics before moving complete content into review.
- Download your edited DDN source to retain the change.
The example uses the indentation-based ddn-next-1 dialect. The language guide explains reusable definitions, dotted data rows and explicit property blocks.