Help on joining 3 tables Oracle XE 11g
The first query you have used returns Cartesian product of the rows from these three tables.
For details: Join

The following is the simple example to join three tables.

SQL&gt; select * from student;

STUDENT_ID FIRSTNAME        LASTNAME
---------- -------------------- --------------------
     1 Will         Smith

SQL&gt; select * from module;

 MODULE_ID NAME
---------- --------------------
     1 Computing

SQL&gt; select * from marks;

STUDENT_ID  MODULE_ID       MARK
---------- ---------- ----------
     1      1         40

SQL&gt; 


SQL&gt; select s.firstname, s.lastname, mo.name Module_Name, m.mark 
     from student s 
         join marks m on (s.student_id=m.student_id) 
         join module mo on (m.module_id=mo.module_id);

FIRSTNAME     LASTNAME     MODULE_NAME     MARK    
------------- ------------ --------------- --------
Will          Smith         Computing      40

SQL&gt;