Last startup time, Oracle

SQL> SELECT STARTUP_TIME FROM V$INSTANCE;

SID

$ env | grep SID
$ echo $ORACLE_SID
SQL> SELECT INSTANCE FROM V$THREAD;

Name

SQL> SELECT NAME FROM V$DATABASE;
SQL> SHOW PARAMETER DB_UNIQUE_NAME;

Status (nomount, mount, open)

SQL> SELECT STATUS FROM V$INSTANCE;
SQL> SELECT STATUS FROM V$THREAD;

State (active)

SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;

Size

SQL> SELECT SUM(BYTES/1024/1024/1024) GB FROM DBA_DATA_FILES;
SQL> SELECT SUM(BYTES/1024/1024/1024) GB FROM V$DATAFILE;

Oracle version

SQL> SELECT * FROM V$VERSION;

DB Parameters

SQL> SHO PARAMETERS
SQL> SHO PARAMETER INSTANCE_NAME

Character set, NLS

SQL> SELECT VALUE$ FROM SYS.PROPS$ WHERE NAME = 'NLS_CHARACTERSET' ;
SQL> SELECT * FROM NLS_DATABASE_PARAMETERS;

If started many processes

SQL> SHOW PARAMATER V$SESSION;
SQL> SHOW PARAMATER V$PROC;