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enter image description hereI am drawing an EER diagram to represent the following relation. The employee can be either supervisor, clerk, assistant or HR. But supervisor can perform all tasks of other roles. Am not sure whether, i need to connect owner to all relations of clerk, assistant and HR. This makes diagram more chaotic.

Since the supervisor can perform all tasks of any other role, should i connect supervisor to tasks of clerk, assistant and HR?

Other than connecting owner to all other tasks, is there any better approach to make diagram simpler?

ringul
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  • The top box should say Employee? PS Please tell us your EER method reference, there are many styles. PS Please [use text, not images/links, for text--including tables & ERDs.](https://meta.stackoverflow.com/q/285551/3404097) Paraphrase or quote from other text. Use images only for what cannot be expressed as text or to augment text. Images cannot be searched for or cut & pasted. Include a legend/key & explanation with an image. Make your post self-contained. – philipxy Jun 16 '19 at 02:49
  • The "connections" are participations in relationships. You are confusing entity types with types of work that have similar names. You want a union of type supervisor & another employee type to be the type of entity that can do a certain type of work; the work sometimes happens to have a name similar to the non-supervisor employee type that is unioned into the entity type that can do it. How you can express this depends on the EER method you are using; but you haven't said what that is. PS Diamonds are relationships. How is a type of work a type of relationship, rather than a type of entity? – philipxy Jun 16 '19 at 02:54
  • @sorry for not posting proper diagram. Please ignore what i placed in diamonds. All am worrying is, Supervisor can perform tasks of all other employees. Consider the following examples, Clerk Project. The same task can be done by supervisor as well. So do i need to have another similar relationship between supervisor and project? Supervisor Project. NOTE: My text inbetween <> represents diamond i.e., relationship. Supervisor, clerk and project are entities. P.S : Am a newbie – ringul Jun 16 '19 at 03:26
  • My comment just told you what to do--make the appropriate subtypes & unions/supertypes. PS EER has subtypes & unions/supertypes. You need to read your method reference. (And tell us what it is if you want help.) Typically in non-E ER one would have binary relationships like 'employee X is supervisor Y'. One could also use unary relationships like "X s an employee". Then one uses those relationships as associative entities. The first E in EER is for idioms that replace the preceding 2 kinds of ER relationships (associative entities) by (non-associative) entities. Just find your Es & Rs. – philipxy Jun 16 '19 at 04:36

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