title: Update an empty cell in a MySQL table
body: <p>I was wondering if there is any way to select an empty cell in a MySQL table and update it's value.</p>
  
  <p>This is the structure of the table :</p>
  
  <pre><code>col 1 | col 2 | col 3  
        | a     | aaaa  
        | a     | aaaa  
        | a     | aaaa  
        | a     | aaaa
  </code></pre>
  
  <p>I would like to have something like </p>
  
  <pre><code>col 1 | col 2 | col 3  
  bbbb  | a     | aaaa  
  bbbb  | a     | aaaa  
  bbbb  | a     | aaaa  
  bbbb  | a     | aaaa
  </code></pre>
  
  <p>Thanks in advance</p>