из хелпа по ADO относительно фильтра..

There is no precedence between AND and OR. Clauses can be grouped within parentheses. However, you cannot group clauses joined by an OR and then join the group to another clause with an AND, like this:
(LastName = 'Smith' OR LastName = 'Jones') AND FirstName = 'John'
Instead, you would construct this filter as
(LastName = 'Smith' AND FirstName = 'John') OR (LastName = 'Jones' AND FirstName = 'John')