title: Select rows which are there in one table and not there in another table by matching two columns values
body: <p>I have two tables as shown below</p>
  <p>t1:</p>
  <pre><code>cust_id   product       score
  1         bat           0.8
  2         ball          0.3
  2         phone         0.6
  3         tv            1.0
  2         bat           1.0
  4         phone         0.2
  1         ball          0.6 
  </code></pre>
  <p>t2:</p>
  <pre><code>cust_id          product
  1                bat
  2                phone
  3                tv
  </code></pre>
  <p>From the above table I would like to filter rows which are there in <code>t1</code> and not in <code>t2</code> by matching the columns <code>cust_id</code> and <code>product</code></p>
  <p>Expected output:</p>
  <pre><code>cust_id   product       score
  2         ball          0.3
  2         bat           1.0
  4         phone         0.2
  1         ball          0.6 
  </code></pre>
  <p>I tried below query but it does not works.</p>
  <pre><code>   SELECT t1.* 
       FROM t1
  LEFT JOIN t2
         ON t1.cust_id = t1.cust_id
       WHERE t2.product IS NUL
  </code></pre>