where [id] = array(*neq*,5); where[*age*] = array(*egt*, 20);
这个变成SQL就是 where id != 5 and age >= 20;
但我现在要更复杂的SQL语句： where (id != 5 and age > 20 ) or (id > 15 and age < 18 ) ;THINKPHP 应该怎写？