Searching for all records but integer field is causing problems

How do I do a select query for all records?

SELECT * FROM phpgw_categories WHERE cat_name = ? AND cat_owner = ? AND
cat_appname = 'notes'

cat_name = '*' works but cat_owner = '*' gives me an atoi error.

I was hoping to reuse the code segment of SQL that gets called repeatedly
for slightly different purposes but I can't get this to work