Exclude Items in Impex batchmode

Is it possible to update all items of a Type but one?
There is a new Category that should be the parent category of all "sub-categories" (Categories that already have a parent).
When I run the following impex, I (obviously) get the error cannot assign subcategory <code>(pk-xxx) as super category of [<code>(pk-xxx)] - cycle detected:

 UPDATE Category[batchmode=true];itemtype(code)[unique=true];$catalogVersion;supercategories(code, $catalogVersion);
 ;Category;$catalog_version;category-code:$catalog_version

Basically, talking in SQL, it would be something like this: UPDATE table SET column=value WHERE another_column <> 'some value'

What is the correct syntax to achieve this, if possible?