----如下语句在某会话执行120次
update t_network set a=a+1;
update t_network set a=a+1;   
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;
update t_network set a=a+1;

--查看某会话的事件
EVENT                                                            TOTAL_WAITS TIME_WAITED AVERAGE_WAIT
---------------------------------------------------------------- ----------- ----------- ------------
SQL*Net message to client                                                143           0            0
SQL*Net message from client                                              142        4748        33.44 --sql*net message from client猛增和to client
Disk file operations I/O                                                   3           0         0.08
log file sync                                                              1           0         0.07

--如果把上述的120次执行的sql用plsql实现又是如何呢
SQL> begin
  2  for i in 1..125 loop
  3   update t_network set a=a+1;
  4  commit;
  5  end loop;
  6  end;
  7  /

PL/SQL procedure successfully completed.

SQL> /
 
EVENT                                                            TOTAL_WAITS TIME_WAITED AVERAGE_WAIT
---------------------------------------------------------------- ----------- ----------- ------------
SQL*Net message to client                                                 15           0            0
SQL*Net message from client                                               14        1727       123.38 --总的等待次数及总的等待时间大为下降
Disk file operations I/O                                                   2           0         0.07
log file sync                                                              1           0         0.11
 
SQL>

小结：如果上述的sql*net message from/to client大量上升，表示sql执行次数很高,从这块入手处理下问题
      这就是为何要用plsql封装重复执行的sql原因，不然oracle与客户端多次交互,会影响客户的响应感觉与响应时间