Connect Identifier

How to Install Oracle Instant Client 19c on Linux

by Ed Chen
March 1, 2023February 15, 2023

Suppose that you have known the differences between Oracle client and Oracle instant client, and decide to install Oracle instant client for your machine. On… Read More »

SQLPlus Connect and Disconnect

by Ed Chen
December 16, 2022February 22, 2023

SQLPlus Connect To connect a database, we usually use sqlplus, a text-based connection tool provided by Oracle to facilitate clients to connect to a running… Read More »

TNSNAMES, How and Why

by Ed Chen
January 18, 2022March 6, 2023

Local Naming = TNSNAMES Whenever we need to connect to the database, we usually provide a connection string like this: SQL> conn username/password@chicago-db-server:1521/ORCL Connected. Or… Read More »

How to Resolve ORA-12505: TNS:listener does not currently know of SID given in connect

by Ed Chen
March 20, 2021June 30, 2022

ORA-12505 ORA-12505 means that the SID you provided in the connect identifier does not match any SID registered with the listener. Basically, SID means $ORACLE_SID,… Read More »

How to Resolve ORA-12154: TNS:could not resolve the connect identifier specified

by Ed Chen
June 8, 2019December 29, 2022
8 Comments

ORA-12154 ORA-12154 means that your connection tools (e.g. sqlplus) cannot use TNSNAMES naming method for some reason. This reminds me that there're same error patterns… Read More »

How to Resolve ORA-12514: TNS:listener does not currently know of service requested in connect

by Ed Chen
February 14, 2019December 10, 2022
28 Comments

ORA-12514 ORA-12514 means that the listener cannot find any matched service with yours, so it cannot establish the connection with the database for you. As… Read More »

How to Resolve TNS-03505: Failed to resolve name

by Ed Chen
February 9, 2019December 10, 2022
2 Comments

TNS-03505 Failing to resolve TNS names could involve any one of the network configuration files, such as tnsnames.ora or sqlnet.ora. There're several possible causes may… Read More »