Database tables within the WebSphere Commerce database schema are organized into functional groups, called data models. The referential integrity relationship between database tables is illustrated using the following symbols:
A rounded, dotted rectangle represents a weak dependent entity. Instances of a weak dependent entity cannot be uniquely identified without determining its relationship to other entities. The primary key to an instance of a weak dependent entity consists entirely of foreign keys.
A rounded, solid rectangle represents a strong dependent entity. Instances of a strong dependent entity cannot be uniquely identified without determining its relationship to other entities. The primary key to an instance of a strong dependent entity contains foreign keys, but does not consist entirely of foreign keys.
A rectangle represents an independent entity. Instances of an independent entity can be uniquely identified without determining its relationship to other entities. The primary key to an instance of an independent entity does not contain any foreign keys.
A solid relationship line represents an identifying relationship. An identifying relationship occurs when instances of the child entity are identified through association with a parent entity. The primary key attributes of the parent entity become primary key attributes of the child.
A dotted relationship line with a solid relationship symbol represents a mandatory non-identifying relationship. A mandatory non-identifying relationship occurs when key attributes from the parent entity must become non-key attributes of the child entity. That is, the inherited non-key attributes of the child entity in this relationship cannot be NULL.
A dotted relationship line with a solid and open relationship symbol represents an optional non-identifying relationship. An optional non-identifying relationship occurs when foreign keys from the parent entity can become non-key attributes of the child entity. That is, the inherited non-key attributes of the child entity in this relationship can be NULL.
A relationship line that links back to the original table indicates a recursive relationship. Recursive relationships must be optional non-identifying relationships.