TIMESTAMP：何时
SQL_REDO：何事
SEG_OWNER, SEG_NAME：受影响对象
USERNAME：执行者
以及很有效的一个字段：
SESSION_INFO：
A possible SESSION_INFOcolumn may contain the following:
-
login_username = HR
-
client_info =
-
OS_username = jkundu
-
Machine_name = nirvan
-
OS_terminal = pts/31
-
OS_program_name = sqlplus@nirvan (TNS V1-V3)