Oracle中一个简单的查询……

Question

“通过查询  V $SESSION_WAIT视图，识别性能的瓶颈，这个动态性能视图列出了造成会话(session)等待的事件。”在书上看到这句话，但我用select * from $SESSION_WAIT 这条语句查询出错，查询视图（$SESSION_WAIT）应该怎么写sql语句啊？请求详解……

Answer 1

select * from v$SESSION_WAIT  前面缺少V

Answer 2

SQL> desc v$session_wait;
Name            Type         Nullable Default Comments 
--------------- ------------ -------- ------- -------- 
SID             NUMBER       Y                         
SEQ#            NUMBER       Y                         
EVENT           VARCHAR2(64) Y                         
P1TEXT          VARCHAR2(64) Y                         
P1              NUMBER       Y                         
P1RAW           RAW(4)       Y                         
P2TEXT          VARCHAR2(64) Y                         
P2              NUMBER       Y                         
P2RAW           RAW(4)       Y                         
P3TEXT          VARCHAR2(64) Y                         
P3              NUMBER       Y                         
P3RAW           RAW(4)       Y                         
WAIT_CLASS_ID   NUMBER       Y                         
WAIT_CLASS#     NUMBER       Y                         
WAIT_CLASS      VARCHAR2(64) Y                         
WAIT_TIME       NUMBER       Y                         
SECONDS_IN_WAIT NUMBER       Y                         
STATE           VARCHAR2(19) Y
SQL> set pagesize 50;
SQL> select sid,seq#,event,state from v$session_wait;       SID       SEQ# EVENT                                                            STATE
---------- ---------- ---------------------------------------------------------------- -------------------
       134        118 SQL*Net message from client                                      WAITING
       137         94 SQL*Net message from client                                      WAITING
       140       1328 SQL*Net message from client                                      WAITING
       141        160 wait for unread message on broadcast channel                     WAITING
       142        125 SQL*Net message from client                                      WAITING
       143       2623 SQL*Net message from client                                      WAITING
       145        150 SQL*Net message from client                                      WAITING
       146          4 SQL*Net message from client                                      WAITING
       147        828 SQL*Net message from client                                      WAITING
       148       1188 SQL*Net message from client                                      WAITING
       149        326 SQL*Net message from client                                      WAITING
       152         49 SQL*Net message to client                                        WAITED SHORT TIME
       155        107 wakeup time manager                                              WAITING
       157          2 rdbms ipc message                                                WAITING
       159         10 rdbms ipc message                                                WAITING
       160          3 Queue Monitor Wait                                               WAITING
       163         31 rdbms ipc message                                                WAITING
       164          6 rdbms ipc message                                                WAITING
       165       1030 smon timer                                                       WAITING
       166        373 rdbms ipc message                                                WAITING
       167        459 rdbms ipc message                                                WAITING
       168        137 rdbms ipc message                                                WAITING
       169          5 rdbms ipc message                                                WAITING
       170          5 pmon timer                                                       WAITING

Answer 3

一 写错了 v$session_wait
二 没有查询v$session_wait的权限  可以用sys 或者是system登录