title: Query is resulting in 1 row with null values when id is not found
body: <p>The exact query:</p>
  <blockquote>
  <p>SELECT
  <code>coupon_coupons</code>.<code>code</code>,<br/>
  <code>coupon_coupons</code>.<code>discountType</code> AS 'type',<br/>
  <code>coupon_coupons</code>.<code>discountAmount</code> AS 'amount',<br/>
  <code>coupon_coupons</code>.<code>discountApplied</code> AS 'applied',<br/>
  <code>coupon_coupons</code>.<code>description</code>,<br/>
  group_concat(<code>coupon_targetsku</code>.<code>sku</code> separator ';') AS 'targetsku' <br/>
  FROM <code>coupon_coupons</code><br/>
  LEFT JOIN <code>coupon_targetsku</code> ON <code>coupon_coupons</code>.<code>code</code> = <code>coupon_targetsku</code>.<code>code</code> <br/>
  WHERE <code>coupon_coupons</code>.<code>code</code> = 'testCode'<br/></p>
  <p>coupon_coupons.code = primary key<br/>
  coupon_targetsku.code = fk(coupon_coupons.code)<br/></p>
  </blockquote>
  <p>If the <code>coupon_coupons</code>.<code>code</code> is found in the database the query operates as expected, but when its not found the result set that is returned is one row with all NULL values. I'm guessing its something I'm doing wrong with the left join.<br/></p>
  <p>I would like this query to return zero rows if the code is not found.<br/></p>
  <p>I'm using mysql:<br/>
  Server version 5.1.36-community-log<br/>
  Protocol version: 10<br/></p>
  <p>Thanks in advance.</p>