Draw an entity-relationship diagram (ERD) for a publishing company that produces indexes of magazine and periodical articles. The following describes the relationships among the entities:
• Each article may have many authors, and each author may write many articles.
• An article may be found in only one periodical, but each periodical will usually contain many articles.
• Each article may have many topics, and each topic may be in many articles.
a. Draw an ERD for the articles, authors, periodicals, and topics based on the above described relationships. Identify relationships among the diagram entities as “one-to-one”, “one-to-many”, “many-to-one”, or “many-to-many”. Identify entities as “entity”, “associative entity”, or “attribute entity.”
b. Draw an ERD in the third normal form for the articles, authors, periodicals, and topics. Identify relationships among the diagram entities as “one-to-one”, “one-to-many”, or “many-to-one”. Identify entities as “entity”, “associative entity”, or “attribute entity”.