ORA-02020: too many database links in use

查询一个sql报错如下：

ERROR at line 113:
ORA-02020: too many database links in use

Cause:The maximum number of active connections to remote databases per user logon has been reached. 

Action:If the user has no open cursors, the current SQL statement accesses more than the maximum allowed remote databases. Otherwise, the user may free remote database connections by closing all cursors that access the databases

解决办法：

SQL> alter system set open_links=15 scope=spfile;
System altered.

SQL> shut immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup

SQL> show parameter open_links
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
open_links                           integer     15