I have a form that lets me search a table based on multiple criteria.  One of these criteria is whether a Yes/No Favorite field in the table is set to Yes.  On the search form, I have a checkbox for Show Favorites.  If this box is checked, the query should only return records where Favorites is Yes.  But if it's unchecked it should return all records.
Since you can't use an iff function in the criteria field, I haven't been able to find a way to do this.  Setting the criteria to Like "*" & [Forms]![FormName]![CheckboxName] & "*" gets me half way there.  If the box is checked it shows only records where favorite is yes.  But unfortunately, when it's not checked it only shows records where favorite is No, instead of all records.