How to "drop database" in DB2 and ORACLE

Here we just show some examples. You know in Oracle you may use different approach to drop a db.
-- in Oracle using SQLPLUS
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount exclusive restrict;
ORACLE instance started.
Total System Global Area  839282688 bytes
Fixed Size                  2217992 bytes
Variable Size             637536248 bytes
Database Buffers          197132288 bytes
Redo Buffers                2396160 bytes
Database mounted.
SQL> drop database;

Database dropped.

-- in DB2
[db2inst1@q1 ~]$ db2 drop db sample2
SQL1035N  The operation failed because the specified database cannot be
connected to in the mode requested.  SQLSTATE=57019
[db2inst1@q1 ~]$ db2 connect to sample2

   Database Connection Information

 Database server        = DB2/LINUXX8664 10.5.0
 SQL authorization ID   = DB2INST1
 Local database alias   = SAMPLE2

[db2inst1@q1 ~]$ db2 quiesce database immediate force connections
DB20000I  The QUIESCE DATABASE command completed successfully.
[db2inst1@q1 ~]$ db2 unquiesce database
DB20000I  The UNQUIESCE DATABASE command completed successfully.
[db2inst1@q1 ~]$ db2 connect reset
DB20000I  The SQL command completed successfully.
[db2inst1@q1 ~]$ db2 drop db sample2
DB20000I  The DROP DATABASE command completed successfully.