title: KDB Query with OR condition like in SQL
body: <p>In SQL I may write query with logical (true and true) or (true and true), i.e:</p>
  
  <pre><code>select * from t1 inner join t2 on ... where (t1.a != t2.a and t1.b != t2.b) or (t1. != t2.a and t1.b != t2.b)
  </code></pre>
  
  <p>when I try to do it in Q like this</p>
  
  <pre><code>select from ej[....] where (t1.a != t2.a and t1.b != t2.b) or (t1. != t2.a and t1.b != t2.b)
  </code></pre>
  
  <p>it fails to compile. </p>
  
  <p>I have also tried this</p>
  
  <pre><code>(t1.a != t2.a and t1.b != t2.b) or (t1. != t2.a and t1.b != t2.b)
  </code></pre>
  
  <p>but it doesn't return the correct result either</p>
  
  <p>How to query it in KDB?</p>