title: Insert record if two values do not exist in MYSQL (same table)
body: <p>I am trying to insert a record into a table only if there is no existing record that contains two values. This query throws error:
  "syntax to use near 'WHERE NOT EXISTS"</p>
  
  <p>I've tried various examples from SO posts but can't seem to get this going.</p>
  
  <pre><code>INSERT INTO tasks_admin2agent 
  (trans_id,category,task_name,task_detail,date_due_d) 
  VALUES 
  ('2186597-L1','Listing','Incomplete Listing Record', 'Please complete the 
  listing record','2018-03-31') 
  WHERE NOT EXISTS 
     (SELECT 
      trans_id,task_name 
      FROM tasks_admin2agent 
      WHERE trans_id = '2186597-L1' 
      AND task_name = 'Incomplete Listing Record'
      )
  </code></pre>