Solution to ORA-12560: TNS: protocol adapter errors

Solution to ORA-12560: TNS: protocol adapter errors
There are three reasons for the problem that caused the ORA-12560: TNS: protocol adapter error:


1. The listening service is not started. On the windows platform, perform the following operations: start --- program --- management tools --- Service, open the service panel, and start the oraclehome92TNSlistener service.

2. The database instance is not started. On windows, perform the following operations: start --- program --- management tools --- Service, open the service panel, start oracleserviceXXXX, and XXXX is your database SID.

3. Registry issues. Regedit, and enter HKEY_LOCAL_MACHINE \ SOFTWARE \ ORACLE \ HOME0 to set the environment variable ORACLE_SID to XXXX. XXXX is your database SID. or right-click my computer, and choose "property"> "advanced"> "environment variable"> "system variable"> "new ".
, Variable name = oracle_sid, variable value = XXXX, XXXX is your database SID. Or before entering sqlplus, enter set oracle_sid = XXXX under command line, XXXX is your database SID.

After the above steps, you can solve the problem.