plsql，为什么plsql的database下拉为空？？要设置TNS_ADMIN环境变量

为什么plsql的database下拉为空？本该有我在tnsnames.ora中设置的字符串ORCL，如下所示：

# tnsnames.ora Network Configuration File: F:\app\user\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)

    )

  )

因为没有设置TNS_ADMIN环境变量，路径是你要显示的tnsnames.org所在的文件夹。

需要设置如下；

TNS_ADMIN

F:\app\installMuLu\product\11.2.0\instantclient_11_2

也可以通过cmd暂时指定

set TNS_ADMIN=C:\instantclient-basic-nt-11.2.0.2.0
start plsqldev.exe