数据库：oracle 19.12
测试目标：视图所依赖的表被删除后，测试对该视图的影响.
操作过程：
SQL> create view v_emp90
  2  as
  3  select employee_id,last_name,salary
  4  from emp;

View created.
SQL> desc emp;
 Name                                                  Null?    Type
 ----------------------------------------------------- -------- ------------------------------------
 EMPLOYEE_ID                                                    NUMBER(6)
 FIRST_NAME                                                     VARCHAR2(20)
 LAST_NAME                                             NOT NULL VARCHAR2(25)
 EMAIL                                                 NOT NULL VARCHAR2(25)
 PHONE_NUMBER                                                   VARCHAR2(20)
 HIRE_DATE                                             NOT NULL DATE
 JOB_ID                                                NOT NULL VARCHAR2(10)
 SALARY                                                NOT NULL NUMBER(8,2)
 COMMISSION_PCT                                                 NUMBER(2,2)
 MANAGER_ID                                                     NUMBER(6)
 DEPARTMENT_ID                                                  NUMBER(4)

SQL> drop table emp purge;

Table dropped.

SQL> select * from v_emp90;
select * from v_emp90
              *
ERROR at line 1:
ORA-04063: view "ORA1.V_EMP90" has errors


SQL> desc v_emp90
ERROR:
ORA-24372: invalid object for describe

SQL> select object_name,object_type,to_char(created,'yyyy-mm-dd hh24:mi:ss') from user_objects where object_type='VIEW';

OBJECT_NAME                    OBJECT_TYPE             TO_CHAR(CREATED,'YY
------------------------------ ----------------------- -------------------
V_EMP80                        VIEW                    2022-06-26 19:09:09
V_EMP50                        VIEW                    2022-06-26 19:19:58
V_EMP                          VIEW                    2022-06-26 19:53:16
V_EMP20                        VIEW                    2022-06-26 19:58:40
V_EMP10                        VIEW                    2022-06-26 20:12:55
V_EMP90                        VIEW                    2022-06-29 13:20:29

6 rows selected.
SQL> drop view V_EMP90;

View dropped.

结论：当表被删除后，依赖该表的视图也变得无效,但是视图名字依然存在.