USE tpch1;
select * from region where ((r_regionkey = 9  and r_comment = 'a') or r_regionkey = 1);
r_regionkey	r_name	r_comment
1	AMERICA	hs use ironic, even requests. s
select * from region where (r_regionkey = 1 or (r_regionkey = 9 and r_comment = 'a'));
r_regionkey	r_name	r_comment
1	AMERICA	hs use ironic, even requests. s