I get a Syntax error (missing operator) in query expression CONVERT and CAST
<p>I tried to use this syntax but keep getting errors. I have tried several variations. I want to convert a string column to an integer and verify it is greater than zero</p>

<pre><code>SELECT CAST(Columnx AS UNSIGNED) FROM HOLD2 where columnx &gt; 0    
</code></pre>

<p>or </p>

<pre><code> SELECT CONVERT(SUBSTRING_INDEX(COLUMNX,'-',-1),UNSIGNED INTEGER) AS CX FROM HOLD2 where cx &gt; 0
</code></pre>

<p>I get an error message: <em>Syntax error (missing operator) in query expression ‘CONVERT……</em>  or <em>'CAST....</em><br>
Any assistance is greatly appreciated.</p>