1、字符型转成timestamp

select to_timestamp('01-10月-08 07.46.41.000000000 上午','dd-MON-yy hh:mi:ss.ff AM') from dual;  

2、timestamp转成date型

select cast(to_timestamp('01-10月-08 07.46.41.000000000 上午','dd-MON-yy hh:mi:ss.ff AM') as date) timestamp_to_date from dual; 

3、date型转成timestamp

select cast(sysdate as timestamp) date_to_timestamp from dual;  

4、获取timestamp格式的系统时间

select systimestamp from dual;