PL/SQL连接Oracle数据库的时候 报"ORA-12514: TNS:监听程序当前无法识别连接描述符中请求的服务" 错误
本例原因：
安装Oracle时一般默认实例都是orcl，发现有人不按套路出牌，改了名字，如图
解决方法：
在Oracle安装目录 找到listener.ora文件 路径为 D:\oracle\product\11.2.0\dbhome_1\NETWORK\ADMIN
(根据自己情况查找) 修改：
# listener.ora Network Configuration File: D:\oracl\prodoracle账号uct\11.2.0\dbhome_1\network\admin\listener.ora# Generated by Oracle configuration tools.SID_LIST_LISTENER =(SID_LIST =(SID_DESC =(SID_NAME = CLRExtProc)(ORACLE_HOME = D:\oracle\product\11.2.0\dbhome_1)(PROGRAM = extproc)(ENVS = "EXTPROC_DLLS=ONLY:D:\oracle\product\11.2.0\dbhome_1\bin\oraclr11.dll"))(SID_DESC =(GLOBAL_DBNAME = JTW)(ORACLE_HOME = D:\oracle\product\11.2.0\dbhome_1)(SID_NAME = JTW)))LISTENER =(DESCRIPTION_LIST =(DESCRIPTION =(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))))
红色部分为新添加内容，JTW为监听的实例名
然后修改(添加)instantclient_11_2\network\admin\tnsnames.ora
MyOracle = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = jtw) ) )
重启Oracle监听