我装了Oracle11gR2，装好之后，用自带的黑窗口SQLplus是可以连数据库的，也可以看到自带的emp,dept等表，可是我又装了 PLSQL Developer，装好之后再登陆框上却看不到数据库，怎么办啊？很急！我看了一下我的tnsnames.ora，内容如下：
# tnsnames.ora Network Configuration File: D:\Oracle\product\11.2.0\dbhome_1\network\admin\tnsnames.ora# Generated by Oracle configuration tools.LISTENER_ORCL = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) ORACLR_CONNECTION_DATA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521)) ) (CONNECT_DATA = (SID = CLRExtProc) (PRESENTATION = RO) ) )ORCL = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl) ) ) 其中ORCL是默认的全局数据库，我就用这个，觉的也没什么问题啊。对了，我操作系统是64位的，装的也是64位的Oracle11gR2我的电脑环境变量：classpath=.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar
path=D:\Oracle\product\11.2.0\dbhome_1\bin;%java_home%\bin;%java_home%\jre\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\
# tnsnames.ora Network Configuration File: D:\Oracle\product\11.2.0\dbhome_1\network\admin\tnsnames.ora# Generated by Oracle configuration tools.LISTENER_ORCL = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) ORACLR_CONNECTION_DATA = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521)) ) (CONNECT_DATA = (SID = CLRExtProc) (PRESENTATION = RO) ) )ORCL = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl) ) ) 其中ORCL是默认的全局数据库，我就用这个，觉的也没什么问题啊。对了，我操作系统是64位的，装的也是64位的Oracle11gR2我的电脑环境变量：classpath=.;%JAVA_HOME%\lib;%JAVA_HOME%\lib\tools.jar
path=D:\Oracle\product\11.2.0\dbhome_1\bin;%java_home%\bin;%java_home%\jre\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\
LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost或IP地址)(PORT = 1521))
)