title: How to call stored procedure with only OUT parameter?
body: <p>I have created a stored procedure in Oracle 11g:</p>
  
  <pre><code>CREATE OR REPLACE PROCEDURE greetings(cnt OUT VARCHAR2) 
  AS 
  BEGIN
      SELECT COUNT(*) 
      INTO cnt 
      FROM SYS.all_tables; 
  END greetings;
  </code></pre>
  
  <p>but I am unable to call it.</p>
  
  <p>I have tried the following code snippets:</p>
  
  <ol>
  <li><code>EXEC GREETINGS();</code></li>
  <li><code>EXEC GREETINGS;</code></li>
  <li><code>CALL GREETINGS;</code></li>
  </ol>