title: difference between select distinct id and select distinct * in sql
body: <p>i tried with </p>
  
  <pre><code>select distinct ID  from  DB.TABLE;
  </code></pre>
  
  <p>it  returned unique ids in all records.</p>
  
  <pre><code>select distinct *  from  DB.TABLE;
  </code></pre>
  
  <p>it will return unique records by comparing all columns and  records  or what is functionality of "distinct *" ,i confused with functionality of distinct * .</p>