Null, which means that the rule is independent of any project. There may exist a row in iam_project_rules whose project_id is Dependent Entities: Depend both for their existence and their identification upon other entities in the model. Independent Entities: An entity which does not depend upon any other entity in a model for its identification. This is possible since the relation is between independent entities, i.e. The optional can only be on the iam_project side, since iam_project_rules is already 'optional' (since there can be zero rules associated with an iam_project). Where is the error in my analysis or assumptions?Īccording to this IDEF1X cheat sheet, the diamond shows a relationship of an optional iam_project with zero, one or many iam_project_rules. There may exist a row in iam_project_rules whose project_id doesīut if iam_project_rules.project_id is a foreign key to iam_projects, which it is, then that claim must be false.

In words, that posits this claim to be true: A given iam_projects.db_id may appear zero or more times in iam_project_rules (hence the solid circle on the right end of the connecting line).Īs I understand the notation, the diamond on the left end of the connecting line changes the left side from 'one' to 'zero or one'.iam_projects.db_id is not part of the primary key of iam_project_rules (hence the dotted line style).iam_projects.db_id is a foreign key in iam_project_rules (the project_id field), hence the connecting line.Our team's DB convention is that each primary table (i.e., not an association-type table) has its own unique primary key called db_id.This diagram (in IDEF1X notation) shows the following: Upon generating an entity-relationship diagram of my database I observed several occurrence like this:

Dbeaver er diagram