How do I solve error 12505 in Oracle SQL? - oracle

Question

I'm a programming student and I just began learning databases and SQL. When I try to connect to the databse in SQL Developer it says
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor.
I tried to install it on my PC tower at home and everything works fine it just doesn't work with my laptop. Even the teacher said he couldn't help me because he doesn't know what to do so I try here because I really don't know what to do.
I tried uninstalling et reinstalling the database multiple times and I made sure every Oracle services were running. My SID is set to XE. My connection is set to basic. The host is 'localhost', the port is '1521' and the SID is 'xe'
Heres is the tnsnames.ora file
XE =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = DESKTOP-62JIG0N)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = XE)
)
)
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
)
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
)
)
ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
)
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
)
)
Heres is the ouput of lsnrctl status in the cmd
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for 64-bit Windows: Version 11.2.0.2.0 - Production
Start Date 03-F╔VR.-2020 12:04:38
Uptime 0 days 4 hr. 53 min. 38 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Default Service XE
Listener Parameter File C:\oraclexe\app\oracle\product\11.2.0\server\network\admin\listener.ora
Listener Log File C:\oraclexe\app\oracle\diag\tnslsnr\DESKTOP-62JIG0N\listener\alert\log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1ipc)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=DESKTOP-62JIG0N)(PORT=1521)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "PLSExtProc" has 1 instance(s).
Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
Here's the listener.ora file
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
(PROGRAM = extproc)
)
(SID_DESC =
(SID_NAME = CLRExtProc)
(ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
(PROGRAM = extproc)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(ADDRESS = (PROTOCOL = TCP)(HOST = DESKTOP-62JIG0N)(PORT = 1521))
)
)
DEFAULT_SERVICE_LISTENER = (XE)

Answer 1

What is the 'connection' type of your SQL Dev connection properties? (basic? TNS?) There is a discconect between the error message ("NS:listener does not currently know of SID") while your tnsnames says to connect by service name rather than by SID. This would indicate that your SQL Dev connection type is 'basic' . . . which doesn't use tnsnames.ora at all. Since you are using a 'basic' connection, you need to show us the values used. Also, since it is the listener complaining that he doesn't know of the sid you are requesting, you need to show us the output of the command 'lsnrctl status', so that we can see what the listener does know about.
This really a pretty basic problem, so the fact that your instructor doesn't know how to solve it leaves me with a lot of questions about his qualifications to be teaching anything involving oracle.