title: How to create MySql VIRTUAL Column that have query string value in it
body: <p>Let me explain . I have a json data set with values something like this:</p>
  
  <pre><code>"clientRequest": {
          "uri": "/flow.php?id=FS-6097&amp;utm_source=facebook&amp;utm_medium=cpc&amp;utm_term=cold",
          "body": null,
          "bytes": 608,
          "flags": 1,     
          "referer": "http://m.facebook.com/",        
          "httpMethod": "GET",
          "httpProtocol": "HTTP/1.1"
      },
  </code></pre>
  
  <p>Now i want to create a Virtual column which only fetch value "FS-6097" from "clientRequest.uri". So a new column which just contains "FS-6097", not just whole uri.</p>
  
  <p>I am already creating a virtual column for whole uri like below, which is fine.</p>
  
  <pre><code>ALTER TABLE `table_xyz_json`
      ADD `url` TEXT
      GENERATED ALWAYS AS (JSON_UNQUOTE(
          JSON_EXTRACT(json_data, '$.clientRequest.uri')
      ))
      VIRTUAL NULL;
  </code></pre>
  
  <p>any help would be highly appreciated . </p>