title: Select a distinct list of substrings from one of the fields in a MySQL table
body: <p>I have rows such as </p>
  
  <ul>
  <li>[ISSUE] This is a sample issue</li>
  <li>[WEBSITE] A bug in the website</li>
  <li>Note that this row doesn't contain anything inside square brackets</li>
  <li>[WEBSITE] Another bug in the website</li>
  <li>[TRACKER] It is not live!</li>
  <li>Some rows will have them in the [middle] but I don't want them</li>
  </ul>
  
  <p>etc..</p>
  
  <p>Assume the field is called "Title" and the table is called "Issues". All items in that column start with a string within square brackets. There is no definitive list of what words can come inside the square brackets. no restriction on the length also. I need not get it if the field doesn't start with such a string.</p>
  
  <p>I want to get the word inside the pair of square brackets and get a unique list of those words.</p>
  
  <p>I want to select a distinct list of all the [XYZ]s. For example, in the list above, the query should return the following list of strings:</p>
  
  <ul>
  <li>ISSUE</li>
  <li>WEBSITE</li>
  <li>TRACKER</li>
  </ul>
  
  <p>It is a combination of substring logic, and distinct query. The logic might go like <strong>Find the index of the first [ and the first ] and get the string between that and from the list, make a unique list</strong>. I am finding it nearly impossible to write it in a single MySQL query. What is the query that will get that list?</p>