title: Retrieving data from another column based on entries in another column within same table
body: <p>I have this table.</p>
  <pre><code>+----+-----------+--------+----------+
  | sku|  strength |  color | option_1 |
  +----+-----------+--------+----------+
  |  1 | 40 lb     | (NULL) | strength |
  |  2 | 50 lb     | black  | color    |
  |  3 | (NULL)    | black  | color    | 
  |  4 | (NULL)    | red    | color    |
  +----+-----------+--------+----------+
  </code></pre>
  <p>I want this table:</p>
  <pre><code>+----+-----------+--------+----------+----------------+
  |sku | strength  | color  | option_1 | option_value_1 |
  +----+-----------+--------+----------+----------------+
  |  1 | 40 lb     | (NULL) | strength | 40 lb          |
  |  2 | 50 lb     | black  | color    | black          |
  |  3 | (NULL)    | black  | color    | black          |
  |  4 | (NULL)    | red    | color    | red            |
  +----+-----------+--------+----------+----------------+
  </code></pre>
  <p>I'm new to mysql. I'm trying to do this index-match or vlookup like query where option_1 determines which column to retrieve data from and send to option_value_1. I wasn't sure if I should do an inner join or a case clause since I have a much larger table with a lot more options than just color and strength.</p>