SQL语句格式化时间字段

SQL> alter session set nls_date_format = 'yyyy-mm-dd hh24:mi:ss';

Session altered.

SQL> /

Session altered.

SQL> select sid,username,sql_exec_start,sql_exec_id from v$session where sql_exec_id is not null;

       SID USERNAME                       SQL_EXEC_START      SQL_EXEC_ID
---------- ------------------------------ ------------------- -----------
        29 SYS                            2012-01-28 17:19:12    16777220