（58）View the Exhibit and examine the parameters.

User A executes the following command to update the TRANS table:

SQL> UPDATE B.trans SET tr_amt = tr_amt + 500 WHERE c_code = 'C005';

Before user A issues a COMMIT or ROLLBACK command, user B executes the following command on the TRANS table:

SQL> ALTER TABLE trans MODIFY (tr_type VARCHAR2(3));

What would happen in this scenario?

A. The ALTER TABLE command modifies the column successfully.

B. The DDL operation gets higher priority and transaction for user A is rolled back.

C. The ALTER TABLE command waits indefinitely until user A ends the transaction.

D. The ALTER TABLE command fails after waiting for 60 seconds due to the resource being busy.

答案：（D）

解析：

--在一个会话中创建和修改表

scott@TESTDB11>create table emp1 as select * from emp;

Table created.

scott@TESTDB11>update emp1 set sal = sal * 2 where empno = 7788;

1 row updated.

--D. 在另一个会话中修改表的定义,这个错误是立即返回的,本答案稍有瑕疵.

scott@TESTDB11>alter table emp1 modify (ename varchar2(30));

alter table emp1 modify (ename varchar2(30))

*

ERROR at line 1:

ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

ITPub博客

Oracle 11G OCP 1Z0-052 58