一周没用过oracle，打开数据库的时候报错：
执行请求的操作时遇到错误:
ORA-01219: 数据库或可插入数据库未打开: 仅允许在固定表或视图中查询
01219. 00000 - "database or pluggable database not open: queries allowed on fixed tables or views only"
*Cause: A query was issued against an object not recognized as a fixed
table or fixed view before the database or pluggable database has
been opened.
*Action: Re-phrase the query to include only fixed objects, or open the
database or pluggable database.
供应商代码 1219
解决：
1、重启电脑，不管用；
2、连接上sys后，执行下面语句：
select open_mode from v$database; alter database open; select con_id,dbid,NAME,OPEN_MODE from v$pdbs;
3、上面语句执行后基本正常，然后切换容器：
alter pluggable database orclpdb open;
alter session set container=orclpdb;