title: MySQL: Find NULLable columns that could be NON NULL
body: <p>I'm struggling with a database that has poor hygiene in regards to NON NULL columns.</p>
  <p>Some columns always have data, i.e. they could be NON NULL, but they aren't.
  Others surprise me when I expect them to always have data but they don't, and I trigger null pointer exceptions.</p>
  <p>I'd like to know which columns have no NULL entries in them, i.e. that could be NON NULL, but that aren't. Right now I know I can do this:</p>
  <pre><code>SELECT DISTINCT(column) FROM table WHERE column IS NULL
  </code></pre>
  <p>But ideally I wouldn't have to do this column-by-column, table-by-table. Is there a way to automate this?</p>