I discovered an interesting quirk in using the Database Configuration Assistant to create and delete a database. When I installed Oracle, and I selected to have the starter database installed, this created an entry called ORACLE_SID in the registry that tells it what database to mount and start with an instance as a default. When I used the DBCA to create a second database, I discovered that the new database overwrote the default value in the registry, so in order to connect to the original database, I have to type its SID into the host string field in the SQL*Plus login box. How did the new database become the default without actually doing the change manually?Then, I deleted the new database using the DBCA, and guess what it did? It deleted the ORACLE_SID entry in the registry for the default_SID. I had to re-enter that entry and type in the SID of the default database again, or else I had to enter the SID every time when using SQL*Plus. Do you know what happened here?
This was first published in October 2004