The oracle11gora-12514 listener is not recognized currently

Environment: win7_x64, oracle11g

Description: The connection fails on the first day of the first day;

2: pl SQL developer Connection Tool, self-installed oracle database, and installed Client

3: oracle clients are not required when oracle is installed. Install plsql developer to operate the database.

Solution:

1: configure the TNS_ADMIN environment variable to the path of the oracle database (E: \ oracle \ product \ 11.2.0 \ dbhome_1 \ NETWORK \ ADMIN ).

2: Open the tnsnames. ora (E: \ oracle \ product \ 11.2.0 \ dbhome_1 \ NETWORK \ ADMIN) file and change the HOST attribute to the computer name of the local machine.

(3: No, cmd -- netca -- local network service name configuration -- delete the corresponding configuration name with an error) quit