title: Is a primary key necessary?
body: <p>In database systems, should every table have a primary key? </p>
  
  <p>For example I have a table <code>table1(foreignkey1,foreignkey2,attribute)</code> like <code>this.table1</code> does not have a primary key. </p>
  
  <p>Should I define a primary key for this table like <code>table1id</code>? </p>