help: create database

Hi, Oracle gurus:

I just start using Oracle7.3 (workgroup server on Solaris 2.5). I downloaded
the trial version and do not have any documentations. Installation is fine. But I got a problem in creating database.

Every time I run sqlplus, it seems to connect to the default database ( whichever my ORACLE_SID environment is pointing to).

My story is:
When I install Oracle7.3, it created a default database instance with SID=WG73. But I killed all oracle7's running process later while I was shutting down the instance, leaving the state of WG73 at "down" , but there is no control file "crtlWG73.dbf" left. So this instance is not working
properly. Then I reinstalled ONLY the default database, specifying SID as GEST. Now GEST is up and running, and my sqlplus can run. But when I change the ORACLE_SID to WG73 (the original), sqlplus cannot run because WG73 in a inconsistant state. Here are my questions:

1. Does sqlplus connect to only one database instance? It seems like that. Can I specify which instance to connect at command line instead of using environment ORACLE_SID? I tried: sqlplus scott/tiger @GEST or sqlplus internal/manager @WG73

But it seems sqlplus ignores the database spec parameter.

2) While I was in GEST using sqlplus, I tried drop database WG73;
The error message told me, it need a "link" keyword. So what is the proper way to delete an existing database?

3) While I use sqlplus in GEST, I tried
create database MYDBASE;
The error always tell me I do not have the privilege even though I tried using INTERNAL, SYSTEM and SYS
So what is the proper way (command) to create a database?

4) Can someone point out what is SID anyway? Is it a database name or what? If so, why restrict it to 4 letter long? Or is it a service ID which
can manage a lot of databases? I am really confused. Besides, if sqlplus only connect to one database, how can I create a different database and then connect to it? Can someone point me to some materials to read as a first time Oracle DBA?

5) I think sqlplus might be the equivalent of "dbaccess" in Informix. When I used dbaccess, I can see a lot of database names, and then I can choose one to connect or create a new one. But How can I see all the databases in sqlplus? And once I choose a database, How can I see all the table infos of that database in sqlplus?

Thanks in advance,
Xiaofeng Cheng Received on Tue Mar 24 1998 - 00:00:00 CST