Summary of trunc function usage

The usage of the trunc function is summarized. During this period, the roaming and call data of the previous month will be counted. Use the trunc function. Trunc (datetime [, fmt]); 1. select trunc (datetime, 'yy') from dual; ----------------------------------------------- 2012-1-1 2, www.2cto.com select trunc (datetime, 'mm') from dual; 3, the entire point of the current time. For example, it is 15:27:12. After processing, we can get 2012-9-20 15: 00: 00 select trunc (datetime, 'hh ') from dual; hour 15:27:12, the whole point of the current time. For example, it is. After processing, we can get 2012-9-20 15: 00: 00 select trunc (datetime, 'mi') from dual; ---------------------------------------------- 2012-9-20 15:27:00 5. To get the specified time for tomorrow, for example, 2012-9-21 08: 21: 43 select trunc (sysdate) + 1 + 1/24*8 + 1/(24*60) * 21 + 1/(24*60*60) * 43 from dual; www.2cto.com 08:21:43 explanation: + 1, plus a day + 1/24*8, + 1/24 is plus 1/24 days, that is, an hour, multiplied by 8, that is, 8 hours; + 1/(24*60) * 2days divided by 24*60 minutes; + 1/(24*60*60) * 43