title: How to set PHYSICAL STANDBY to "READ ONLY WITH APPLY" mode
body: <p>I have standby database(version : Oracle Database 11g Enterprise Edition Release 11.2.0.1.0) in "MOUNTED" mode.</p>
  
  <pre><code>SQL&gt; select database_role,open_mode from v$database;
  
  DATABASE_ROLE    OPEN_MODE
  ---------------- --------------------
  PHYSICAL STANDBY MOUNTED
  </code></pre>
  
  <p>when i want to change OPEN_MODE from "MOUNTED" to "READ ONLY WITH APPLY" mode, the error(ORA-01093) will be occurred.</p>
  
  <pre><code>SQL&gt; SHUTDOWN IMMEDIATE;
  ORA-01109: database not open
  
  
  Database dismounted.
  ORACLE instance shut down.
  SQL&gt; STARTUP MOUNT;
  ORACLE instance started.
  
  Total System Global Area 2.7793E+10 bytes
  Fixed Size                  2189008 bytes
  Variable Size            1.1207E+10 bytes
  Database Buffers         1.6576E+10 bytes
  Redo Buffers                7385088 bytes
  Database mounted.
  SQL&gt; ALTER DATABASE OPEN READ ONLY;
  
  Database altered.
  
  SQL&gt; ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;
  ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION
  *
  ERROR at line 1:
  ORA-01093: ALTER DATABASE CLOSE only permitted with no sessions connected
  </code></pre>
  
  <p>how to fix the error, in other words how to kill other sessions?</p>