title: How to get the intersection of two columns
body: <p>For instance I have table A and table B</p>
  
  <p>a.data = {1,2,3,4,5,6}
  b.data = {4,5,7}</p>
  
  <p>If you want to lookup one value in a.data or b.data you can use FIND_IN_SET(3, b.data).
  But I want to know if at <em>least</em> all the values of b.data are in a.data, or else if I can find
  at least the intersection between b.data and a.data. So in this case {4,5}.</p>
  
  <p>WHERE INTERSECT(a.data, b.data) ... something like that. How should I do this in MySQL?</p>
  
  <p><em>update</em></p>
  
  <p>The b.data {4,5,7} is the column data of one 1 record, so joining a.data on b.data won't work.</p>
  
  <pre><code>table A  
  =======
  ID     DATA  
  1      {1,2,3,4,5,6}  
  2      {7,9,12}  
  
  table B  
  =======  
  ID     DATA  
  1      {4,5,7}  
  2      {9,10,11,12}
  </code></pre>