title: Update single column in a table with with multiple conditions in the WHERE statement
body: <p>I am trying to write an UPDATE statement to update a column in a table based on multiple WHERE conditions. See query below,</p>
  <pre><code>UPDATE table_new
  SET col_4 = 'new value'
  WHERE ?
  (SELECT col_1, col_2, col_3 FROM table_new
  EXCEPT
  SELECT col_1, col_2, col_3 FROM table_old);
  </code></pre>
  <p>I trying to update col_4 with the new value for the unique col_1 + col_2 + col_3 combination coming from the EXPECT SQL query. I am not sure about what would follow the WHERE condition as the WHERE clause is usually followed by just one column in an UPDATE statement. I am thinking of doing a CONCAT for the unique col_1 + col_2 + col_3 combination for both the EXPECT SQL query and the column name that would follow the WHERE clause but not sure if that would help my case</p>
  <p>My possible solution:</p>
  <pre><code>UPDATE table_new
  SET col_4 = 'new value'
  WHERE CONCAT('col_1','-','col_2','-','col_3') IN
  (SELECT CONCAT('col_1','-','col_2','-','col_3') FROM table_new
  EXCEPT
  SELECT CONCAT('col_1','-','col_2','-','col_3') FROM table_old
  );
  
  </code></pre>
  <p>Sample Data in table_new (Before running the UPDATE statement):</p>
  <pre><code> Col_1   Col_2  Col_3  Col_4 (old value)
   123456  123XYZ 456ABC  100
   654321  ZYX321 CBA654  200
  </code></pre>
  <p>Desired Result in table_new (After running the UPDATE statement):</p>
  <pre><code>Col_1   Col_2  Col_3  Col_4 (new value)
   123456  123XYZ 456ABC  300
   654321  ZYX321 CBA654  400
  </code></pre>