title: JPA entity for a table without primary key
body: <p>I have a MySQL table without primary key, and I have to map it into a JPA entity. I cannot modify the table in any way.</p>
  
  <p>Because entities must have a primary key, I have to specify one. If I'm certain that the field I use as a primary key in the entity (or the fields, should I opt for using composite primary key) will always be unique (and not null) in table, can the fact that the table doesn't have a primary key specified in CREATE TABLE cause any issues?</p>