Predicates I page 2
Logical operators as arithmetic ones are being estimated in accordance with their seniority.
One-place operation NOT has highest priority. We can assure ourselves if we'll execute the two following queries.
Parentheses can change the order of estimation of logical operators:
Next priority has AND operator. Compare results of the following queries.
If you are afraid to forget the order in which logical operators are being estimated, use the parentheses.