tnsnames.ora文件里边SERVICE_NAME的参数值--对于动态注册和静态注册，该参数有不同的取值
对于动态注册：
The following pfile/spfile parameters are important when setting the value
for SERVICE_NAME in the tnsnames.ora file:
DB_NAME
DB_DOMAIN
SERVICE_NAMES
一句话概括：
Use the values of the parameters existing in the pfile or spfile,
namely DB_NAME and DB_DOMAIN to determine the value of the SERVICE_NAME that should be used in the TNSNAMES.ORA.
即是：SERVICE_NAME=DB_NAME.DB_DOMAIN
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对于静态注册：
If using statically defined SIDs in the listener.ora file under SID_DESC, the
GLOBAL_DBNAME parameter (within SID_DESC) must match the value set in the
tnsnames.ora file for SERVICE_NAME.
即是：SERVICE_NAME=GLOBAL_DBNAME parameter（listener.ora文件中）
附1：listener.ora文件中GLOBAL_DBNAME的含义：
--来自：Global Database Name Explained (Doc ID 115499.1)
In the LISTENER.ORA file, under the sections SID description, a parameter
GLOBAL_DBNAME can be found. This parameter identifies the database by its
global database name and consists of the name and domain name of the database,
as given in SERVICE_NAMES parameter in the database initialization parameter
file (init<SID>.ora).
即是：GLOBAL_DBNAME=consists of the name and domain name of the database
The value of this parameter is used by the Oracle Intelligent Agent to
determine the service name of the database. Detailed information about this
LISTENER.ORA parameter can be found in Note:97066.1 "How the Intelligent
Agent determines a database service name".
附2：
数据库初始化参数service_names的含义：
默认情况下，service_names为DB_NAME.DB_DOMAIN