title: LEFT JOIN returns same result as INNER JOIN
body: <p>I have one table (scrubs) with 1600 unique items. A second table with 1 million plus. I run my INNER JOIN and get 65 matches:</p>
  
  <pre><code>SELECT a.`BW Parent Number` , a.`Vendor Name`, b.`Parent Supplier Name` 
  FROM `scrubs` AS a
  JOIN pdwspend AS b ON a.`BW Parent Number` = b.`Child Supplier ID`
  WHERE a.`year` =2014
  AND b.`BU ID` = 'BU_1'
  AND b.version LIKE '%GOV%'
  GROUP BY a.`BW Parent Number` 
  </code></pre>
  
  <p>Then I run a LEFT OUTER JOIN and I get the same, 65 results:</p>
  
  <pre><code>SELECT a.`BW Parent Number` , a.`Vendor Name`, b.`Parent Supplier Name`  
  FROM `scrubs` AS a
  LEFT OUTER JOIN pdwspend AS b ON a.`BW Parent Number` = b.`Child Supplier ID` 
  WHERE a.`year` =2014
  AND b.`BU ID` = 'BU_1'
  AND b.version LIKE '%GOV%'
  GROUP BY a.`BW Parent Number`
  </code></pre>
  
  <p>Why is not bringing all the rows from the left table and showing NULL for the ones that don't match under b.<code>Parent Supplier Name</code> ?</p>
  
  <p>Thanks!</p>