Added an installation til to oracle

Author: meeeejin

README.md

@@ -79,7 +79,7 @@ TIL is a collection of the things that I learned today. The contents can be anyt
 
 ### Oracle
 
-- [Istall Oracle 12c on Ubuntu]()
+- [Install Oracle 12c on Ubuntu](oracle/install-oracle-12c-on-ubuntu.md)
 - [How to clean UNDO tablespaces](oracle/how-to-clean-undo-tablespaces.md)
 - [Solution to ORA-03113](oracle/solution-to-ora-03113.md)
 

oracle/install-oracle-12c-on-ubuntu.md

@@ -0,0 +1,11 @@
+# Install Oracle 12c on Ubuntu
+
+- [Install Oracle Database 12c on Ubuntu 16.04](https://medium.com/venturenxt/install-oracle-database-12c-on-ubuntu-16-04-c081d51c0f9d)
+
+If `[INS-20802] Oracle Net Configuration Assistant failed.` error occurred, add the current host name to `/etc/hosts` file. My `/etc/hosts` is as follows:
+
+```bash
+127.0.0.1 localhost
+127.0.0.1 oracle
+127.0.1.1 mijin
+```