title: What is difference between Join and doing same thing with subquery?
body: <p>I have tblProducts and NioaProducts.
  tblProducts is look like this : 
  id | productId | skuCode | manCode |.....</p>
  
  <p>NioaProducts looks like this :
  partNo | manuCode | price |....</p>
  
  <p>Now, I am executing this two queries where I am getting different counts,</p>
  
  <pre><code> SELECT     COUNT(manCode) AS Expr1
   FROM         tblProducts p
   WHERE     (manCode IN
                            (SELECT     manuCode
                              FROM          NioaProducts))
  </code></pre>
  
  <p>This gives me o / p: 10057</p>
  
  <p>Now I am doing same thing with inner join</p>
  
  <pre><code>   SELECT     COUNT(manCode) AS Expr1
       FROM         tblProducts p inner join NioaProducts n on p.manCode = n. manuCode
  </code></pre>
  
  <p>This gives me o/p: 11481</p>
  
  <p>I just want to know which query is correct and why both results are different?</p>