SQL> create tablespace ts1 datafile size 10m;

Tablespace created.

SQL> create table t1 (c1 date) tablespace ts1;

Table created.

SQL> drop tablespace ts1;

Tablespace dropped.

SQL> insert into t1 values(sysdate);
insert into t1 values(sysdate)
            *
ERROR at line 1:
ORA-00959: tablespace 'TS1' does not exist


SQL> drop table t1;
drop table t1
           *
ERROR at line 1:
ORA-00959: tablespace 'TS1' does not exist


SQL> create tablespace ts1 datafile size 10m;

Tablespace created.

SQL> drop table t1;

Table dropped.

SQL> create undo tablespace undo2 datafile size 20m;

Tablespace created.

SQL>  create table t2(c1 date) tablespace undo2;

Table created.

SQL> insert into t2 values(sysdate);
insert into t2 values(sysdate)
            *
ERROR at line 1:
ORA-30022: Cannot create segments in undo tablespace


SQL> alter table t2 move tablespace ts1;

Table altered.