If then In a query Statement

[dgaller]

I am stumped and need some help I have a simple select query used in a combo box to filter what is shown. As shown below.

SELECT [Task Type Drop].[Task Type Id], [Task Type Drop].[Task Type], [Task Type Drop].[Task Category], [Task Type Drop].[Task Type Definition]
FROM [Task Type Drop]
WHERE ((([Task Type Drop].[Task Category])=[Forms]![Task Category and Area Look up]![Combo158]))
ORDER BY [Task Type Drop].[Task Type];

Is is possible to only have it use the criteria if a nother field [Combo158] is not null?

Simply put I would like it to be if [Combo158] is null

SELECT [Task Type Drop].[Task Type Id], [Task Type Drop].[Task Type], [Task Type Drop].[Task Category], [Task Type Drop].[Task Type Definition]
FROM [Task Type Drop]
ORDER BY [Task Type Drop].[Task Type];

If not null

SELECT [Task Type Drop].[Task Type Id], [Task Type Drop].[Task Type], [Task Type Drop].[Task Category], [Task Type Drop].[Task Type Definition]
FROM [Task Type Drop]
WHERE ((([Task Type Drop].[Task Category])=[Forms]![Task Category and Area Look up]![Combo158]))
ORDER BY [Task Type Drop].[Task Type];

 

[pbaldy]

One way:

http://www.mvps.org/access/queries/qry0001.htm

 

[dgaller]

Can't get much simpler than that. It worked thanks!