Oracle ORA-12519: TNS:no appropriate service handler found 解决

select count(*) from v$process --当前的连接数

select value from v$parameter where name = 'processes' --数据库允许的最大连接数

修改最大连接数:

alter system set processes = 300 scope = spfile;

重启数据库:
shutdown immediate;
startup;

--查看当前有哪些用户正在使用数据

SELECT osuser, a.username,cpu_time/executions/1000000||'s', sql_fulltext,machine

from v$session a, v$sqlarea b

where a.sql_address =b.address order by cpu_time/executions desc;

select count(*) from v$session;

show parameter processes

show parameter sessions

alter system set processes=300 scope=spfile;
alter system set sessions=300 scope=spfile;