Nothing out there.
 

SQL> select * from user_tables;

no rows selected
 

Run the file to create the three tables.
 


SQL> @164-db1.sql

Table created.

DROP INDEX XPKCUSTOMER
*
ERROR at line 1:
ORA-01418: specified index does not exist

Index created.

Table altered.
.......
.......

Trigger created.
 

What has been created:
 


SQL>select distinct table_name from user_tables;

TABLE_NAME
------------------------------
CUSTOMER
INVOICE
PRODUCT
 

The empty customer table.
 


SQL> describe customer;
 Name                            Null?    Type
 ------------------------------- -------- ----
 ID                              NOT NULL NUMBER
 FIRST_NAME                               VARCHAR2(20)
 LAST_NAME                                VARCHAR2(20)
 

Dropping the tables.  Why drop invoice first?
 


SQL> drop table invoice;

Table dropped.

SQL> drop table product;

Table dropped.

SQL> drop table customer;

Table dropped.