SQL query ORA-12170 TNS Connection Timeout Special cause

Generally for ORA-12170 this problem

1 See if the data IP can ping through

2 The database service is started

3 server firewall where database service resides

However, when you can go into the data, and report this mistake:

1 See the database connection in the code is write wrong

2 If the confirmation is not a problem, see if there is a dblink-related table query in your SQL, Dblink connection whether there is a problem or IP changes

Since the production environment database IP changes forget to modify, dblink related table query, unexpectedly spent half an hour looking for errors, it is embarrassing ...

SQL query ORA-12170 TNS Connection Timeout Special cause