# @Entity

* A Class that will be mapped to an actual DB Table
  * Also called an Entity Class
* By default, the Class's `Camel Case` naming is matched to table names using `Underscore(_)` naming
  * ex)
    * SalesManager.java → sales\_manager
* Setter methods should not be created in Entity Classes
  * Why?
    * Because it is not clearly distinguishable in code when and where the instance values of the class should change
  * If field value changes are needed, a method with a clear purpose and intention should be added
    * ex) A function that sets the order status → setStatus (x), cancelOrder (o)
* Entity Classes basically populate values through a `constructor` and INSERT into the DB
  * When value changes are needed, a public method corresponding to the event is called to make the change
* A `Builder` can be used instead of a constructor to make it clearer which field gets which value
  * ex)
    * In the code below, the results of Example(a,b) and Example(b, a) would be different

      ```java
      public Example(String a,String b) {
        this.a=a; this.b=b;
      }
      ```
    * Using a `Builder` makes the order irrelevant