title: postgresql delete with select condition
body: <p>I am trying to delete data by using subquery after condition, but my trick fail when my sql script is executed 
  this is my script:</p>
  
  <pre><code>--trying to insert subquery after "=" operator
  
  delete from wni_layanan where id = SELECT (currval('wni_layanan_id_seq'));
  </code></pre>
  
  <p>this is error message who apears in my sqleditor after script executed</p>
  
  <pre><code>ERROR: syntax error at or near "SELECT"
  SQL state: 42601
  Character: 36
  </code></pre>
  
  <p>how to delete with select condition in postgresql ?
  please give me solution to solve my problem. thank you</p>