title: How to execute an (expression involving columns of the same table) stored in another column of the table?
body: <p>My table will look like this-</p>
  
  <pre class="lang-none prettyprint-override"><code>id     | expression                           | unit_cost | demand |total_cost|
  ------ | -------------------------------------| ----------|--------|----------|
  1      | (unit_cost*4)*demand                 | 5         |100     |          |
  2      | (unit_cost*(8/100)demand)*demand     | 10        |50      |          |
  </code></pre>
  
  <p>Now, I want to calculate total_cost based on the expression column using the other columns as specified in the expression. Changes in schema can be done, its just a sample to show what i actually want to do.</p>
  
  <p>Note: expressions will be different for each row</p>