SQL> begin
2 if null>0 then dbms_output.put_line('greater than 0');
3 end if;
4 if not (null>0) then dbms_output.put_line('not greater than 0');
5 end if;
6 end;
7 /PL/SQL 过程已成功完成。为什么2个计算条件的结果都是FALSE?
2 if null>0 then dbms_output.put_line('greater than 0');
3 end if;
4 if not (null>0) then dbms_output.put_line('not greater than 0');
5 end if;
6 end;
7 /PL/SQL 过程已成功完成。为什么2个计算条件的结果都是FALSE?
所以表达式中含有NULL,返回结果均为FALSE
is null
is not null