title: Oracle SQL Developer: PL/SQL: ORA-00903: invalid table name
body: <p>I am getting this error:</p>
  
  <pre><code>Error starting at line 2 in command:
  BEGIN
    DELETE * FROM book_copies;
    DELETE * FROM books;
    /* more code here */
  END;
  Error report:
  ORA-06550: line 2, column 10:
  PL/SQL: ORA-00903: invalid table name
  ORA-06550: line 2, column 3:
  PL/SQL: SQL Statement ignored
  ORA-06550: line 3, column 10:
  PL/SQL: ORA-00903: invalid table name
  ORA-06550: line 3, column 3:
  PL/SQL: SQL Statement ignored
  06550. 00000 -  "line %s, column %s:\n%s"
  *Cause:    Usually a PL/SQL compilation error.
  *Action:
  </code></pre>
  
  <p>Which is ridiculous as both tables exist in my database. I can do:</p>
  
  <pre><code>SELECT * FROM books;
  </code></pre>
  
  <p>Or:</p>
  
  <pre><code>SELECT * FROM book_copies;
  </code></pre>
  
  <p>And both of them work.</p>
  
  <p>Why does Oracle SQL Developer says "invalid table name"?</p>