dbQuery check for null results

Hi Travis,

I have reviewed your query, and I understand why you added 'select null as something' as a check to handle empty results. However, I wanted to provide you with a bit more context. Let me explain a working example script with you.

<arc:set attr="db.driver" value="System.Data.CData.MySql" />
<arc:set attr="db.conn" value="Server=localhost;Database=new;UID=****;Password=****;"/>
<arc:set attr="db.query" value="SELECT * FROM `test`"/>
<arc:set attr="output.data"><Items>
<arc:call op="dbQuery" item="db">
<test>
<arc:enum item="db">
<arc:if exp="[_attr | startswith('db:')]">
<[_attr | split(:,2)]>[_value]</[_attr | split(:,2)]>
</arc:if>
</arc:enum>
<arc:else>
<arc:throw code="myerror" desc="null Value" />
</arc:else>
</test>
</arc:call>
</Items>
</arc:set>
<arc:set attr="output.filename" value="test.txt" />
<arc:push item="output" />

What this script does

• It sets up a database connection (MySQL in this case).

• Runs the query SELECT * FROM ‘test’.

• Iterates through the results (arc:enum item=”db”) and outputs each row/column.

• If no data is returned, the <arc:else> branch is triggered and throws a custom error (null Value). You can modify the error description in this line according to your needs: <arc:throw code="myerror" desc="null Value" />

So, in effect, you don’t need to rely on comparing the raw <table></table> output — this script gracefully handles the case where no records are returned by explicitly checking and throwing an error if the result is null/empty.

If scripting is the only option in your current use case, this solution works fine. But for cleaner handling and long-term maintainability, we recommend using a dedicated database connector (like the MySQL connector). Connectors usually provide built-in ways to handle empty result sets or errors, so you won’t need to manually check for <table></table> or add workarounds.

I hope this helps you achieve your use case. Please feel free to reach out to us at [email protected] if you have any further questions.