![]() It’s a relationship with the same entity. In which table we will include these attributes will be discussed in Database Mapping in the next tutorial. And if an employee may or may not manage a department, this is sketched by a single line and called “partial or optional participation”.Ī relationship itself can have attributes. ![]() So, for example, if an employee must work for a department, this is sketched by double lines, and called “total or mandatory participation”. The lines connecting an entity with a relationship whether single or double line refers to another constrain (we talked about earlier) called “Existence Dependency Constraint” (also called “Participation Constraint”). You can sketch the type of the relationship, whether one-to-many using “1-M”, or many-to-many using “M-N”, or one-to-one using “1–1”.
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