ORA-12546: TNS:permission denied

I recently faced this error message while trying to connect with the database (running on my local Windows host) using a TNS service. Although connecting without TNS service was working fine, however, connection was failing with ORA-12546 when I tried to connect using TNS service. Following is what I faced.

ORA-01511 and ORA-01523

While renaming a datafile or redo log file you might face these both errors together and command would fail as shown below.

SQL> ALTER DATABASE RENAME FILE ‘d:\oracle\oradata\db\users01.dbf’ to ‘e:\oracle\oradata\users01.dbf’; ALTER DATABASE RENAME FILE ‘d:\oracle\oradata\db\users01.dbf’ to ‘e:\oracle\oradata\users01.dbf’; * ERROR at line 1: ORA-01511: error in renaming log/data files ORA-01523: cannot rename datafile to d:\oracle\oradata\db\users01.dbf’ – File already part of database

ORA-01000: maximum open cursors exceeded

Cursor is a pointer to a memory area which is opened to execute an SQL statement issued by the end user/application. It means that every SQL (SELECT/DML) you want to execute would require utilizing this memory area to execute the SQL.