在oracle学习中遇到的问题

select round(123.546,1.9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999) from dual;

再多一个9会显示

而到了这么多个9时

 select round(123.546,1.999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999) from dual;

这数竟然不见了

 但到了最右端，就有显示一堆9

如果多输入一个9，就会显示这个