<p>I have a SQL query (MS Access) and I need to add two columns, either of which may be null. For instance:</p>

<pre><code>SELECT Column1, Column2, Column3+Column4 AS [Added Values]
FROM Table
</code></pre>

<p>where Column3 or Column4 may be null. In this case, I want null to be considered zero (so <code>4 + null = 4, null + null = 0</code>).</p>

<p>Any suggestions as to how to accomplish this?</p>

Since ISNULL in Access is a boolean function (one parameter), use it like this:
```
```
SELECT Column1, Column2, IIF(ISNULL(Column3),0,Column3) + IIF(ISNULL(Column4),0,Column4) AS [Added Values]
FROM Table
```
```