Oracle中timestamp转换成date

获得当前时间：

select sysdate from dual;

select systimestamp from dual;

timestamp to date:(隐式转换)

select systimestamp+0 from dual;

特别是表中日期字段类型为timestamp时 获取时间差时特别有用

如：t.birth 为timestamp类型 获取出生到当前有多少天：

select round(to_number(sysdate-(t.birth+0))) from dual;

当然可以先to_char再to_date 但有点麻烦