细心的小伙伴可以发现，我们在gv$pdbs中，并没有发现con_id=1,con_id=0

其实如果仔细猜一下也应该能猜到：
因为CDB 是由root container,seed pdb container,0个或者多个pdb container组成的。

查询官档 v$pdbs视图：

CON_ID

The ID of the container to which the data pertains. Possible values include:

•0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

•1: This value is used for rows containing data that pertain to only the root

•n: Where n is the applicable container ID for the rows containing data

所以CON_ID =1 是rootcontainer，