title: why left join and inner join returns same result
body: <pre><code>branch_id   branch_name
  1       Branch A
  2       Branch B
  
  user_id username    branch_id
  1   abc     1
  2   def     1
  3   ghi     2
  4   jkl     1
  5   lmn     2
  6   opq     2
  </code></pre>
  
  <p>query 1</p>
  
  <pre><code>query1="select a.branch_id,b.branch_id,a.branch_name from branch a LEFT JOIN user_mast b on a.branch_id=b.branch_id";
  </code></pre>
  
  <p>query 2</p>
  
  <pre><code>$query2="select a.branch_id,b.branch_id,a.branch_name from branch a INNER JOIN user_mast b on a.branch_id=b.branch_id";
  </code></pre>
  
  <p><strong>WHY LEFT JOIN and INNER JOIN results are same.</strong></p>