title: Extracting ISO dates from a JSON Data type
body: <p>I am using MySQL json data type to store a JSON string.
  In the JSON string are two fields: <code>entry_time</code>, and <code>entry_date</code>. The values for these fields are stored in ISO 8609 format as follows:</p>
  
  <pre><code>entry_date:2017-02-15T00:00:00.00Z
  entry_time:0000-00-00T04:35:51.29Z
  </code></pre>
  
  <p>I am trying to create a virtual column from these two attributes. Since MySQL 5.7 has <code>NO_ZERO_DATE</code> set I cannot see a way to extract these values out as date and time columns.  Here is what I have tried:</p>
  
  <pre><code>alter table odh
  add entry_time time GENERATED ALWAYS AS (REPLACE,(json_extract(jdoc,'$.entry_time')),'0000-00-00T','')
  </code></pre>
  
  <p>But I cannot get the sot work either Any help would be greatly appreciated!</p>