title: Database Entity Relationship Diagram and Enhanced Entity Relationship Diqgram
body: <p>I am learning database management systems now. May I know is it required for a weak entity to have an attribute or have a primary key itself? (ERD)</p>
  
  <p>Next, when transforming many to many (M:N) relationship to <strong>1 to many relationships</strong>, the participation constraint <code>mandatory</code> against parent entity is it always the same?(EERD)</p>
  
  <p>Lastly,
  Why do we have to place attributes on the relationship in <code>M:N</code> ? (ERD)</p>