title: SQL Primary Key/Table Joining
body: <p>Alright, this is a relativly simple question that I just need confirmation on. I am pretty sure I know the answer, but I need expert validation because I have OCD.</p>
  
  <p>Anyways, I am wondering what the difference is between just a simple Inner Join Statement
  and simply using the where clause to set the primary keys of the tables I am matching as = to each other.</p>
  
  <p>Example: I wrote this</p>
  
  <pre><code>select a.CONTACT_ID, a.TRADE_REP as Rep_Trading_ID, p.CRD_NUMBER, c.FIRST_NAME, c.LAST_NAME
  from dbo.REP_PROFILE p, dbo.REP_ALIAS a, dbo.CONTACT c
  where 
  c.CONTACT_ID = p.CONTACT_ID
  and p.CONTACT_ID = a.TRADE_REP 
  and a.PRIMARY_YN = 'y'
  </code></pre>
  
  <p>In my mind, this seems to perform the exact same query as if I were to have created and Inner Join between tables c and p and another inner join between tables p and a on Contact ID (Contact ID is my primary key for most everything) </p>
  
  <p>Am I correct? Am I partially correct? Am I tottally hopelessly ignorant? Any validation will do</p>