title: How do I exclude the rows with '0' values but not the rows with NULL values in SQL?
body: <p>I have a column <code>reference</code> under my table. It includes <code>NULL</code>, <code>0</code> and <code>1</code> as its values. I want to exclude the rows that contain <code>0</code>. Also, I want the rows with <code>NULL</code> values to appear. I tried doing <code>reference != 0</code> but it also excludes the rows with <code>NULL</code> value. How do I prevent that?</p>