title: Extract JSON object's values as array from MySQL JSON column
body: <p>I have a MySQL column of json type.  In there, a dict like JSON object is stored.  Now, I want to extract the values from this JSON object and create a JSON array.</p>
  
  <p>How can I achieve this?</p>
  
  <h3>Example Query</h3>
  
  <pre><code>with json_objs(json_col) as (
    select CAST('{"key1": "value1", "key2": "value2"}' AS JSON)
    UNION ALL
    select CAST('{"key3": "value3", "key4": "value4"}' AS JSON)
  )
  select SOME_EXPR_I_CAN_T_FIGURE_OUT from json_objs
  </code></pre>
  
  <h3>Expected result</h3>
  
  <pre><code>+----------------------+
  | resulting_column     |
  +----------------------+
  | ["value1", "value2"] |
  | ["value3", "value4"] |
  +----------------------+
  </code></pre>
  
  <h3>(If table DDL is desired:)</h3>
  
  <pre><code>CREATE TABLE `json_objs` (
    `json_col` json DEFAULT NULL
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8
  </code></pre>