title: Joining multiple Tables in Oracle gives out duplicated records
body: <p>I am a newbie to sql. I have three tables <code>mr1,mr2,mr3</code>. <code>Caseid</code> is the primary keys in all these tables. I need to join all these table columns and display result.
  Problem is that i dont know which join to use.
  when i joined all these just like below query:</p>
  
  <pre><code>select mr1.col1,mr1.col2,mr2.col1,mr2.col2,mr3.col1,mr3.col2
  from mr1,mr2,mr3
  where mr1.caseid = mr2.caseid
  and mr2.caseid = mr3.caseid;
  </code></pre>
  
  <p>it displays 4 records, eventhough the maximum number of records is two, which is in table <code>mr2</code>.
  records are duplicated, can anyone help me in this regard?</p>