title: How to change data type in KDb+?
body: <p>I have created table as following in KDb+: </p>
  
  <pre><code>test:([doc_id:`symbol$()];doc_displayid:`symbol$();doc_created_date:`date$();doc_aacess_date:`timestamp$();is_native_exist:`boolean$();file_size:`real$())
  </code></pre>
  
  <p>Now I want to change the datatype of column <code>doc_id</code> from <strong><code>symbol</code></strong> to <strong><code>int</code></strong>.</p>
  
  <p>How can I alter the test table and change <strong>datatype</strong>?</p>