下列各类设备中，哪些设备要考虑系统短路电流产生的动稳定和热稳定效应（）。 变压器。 电容器。 电流互感器。 电压互感器。 断路器。 耦合电容器。 避雷器等。
Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE You issue these statements: CREATE table new_emp ( employee_id NUMBER, name VARCHAR2(30)); INSERT INTO new_emp SELECT employee_id , last_name from employees; Savepoint s1; UPDATE new_emp set name = UPPER(name); Savepoint s2; Delete from new_emp; Rollback to s2; Delete from new_emp where employee_id =180; UPDATE new_emp set name = 'James'; Rollback to s2; UPDATE new_emp set name = 'James' WHERE employee_id =180; Rollback; At the end of this transaction, what is true?（） You have no rows in the table.。 You have an employee with the name of James.。 You cannot roll back to the same savepoint more than once.。 Your last update fails to update any rows because employee ID 180 was already deleted.。
在液相液化石油气输送过程中，要求管道中任何一点的压力都要（）管道中液化石油气所处温度下的饱和蒸汽压。 小于或等于；。 高于；。 等于；。 低于。
What is true regarding subqueries?（） The inner query always sorts the results of the outer query.。 The outer query always sorts the results of the inner query.。 The outer query must return a value to the inner query.。 The inner query returns a value to the outer query.。 The inner query must always return a value or the outer query will give an error.。
产品未必具备人们所期望的性能而存在的风险是（） 功能风险。 安全风险。 经济风险。 社会风险。
Your test database is running in NOARCHIVELOG mode. Which statement is true regarding the type ofbackups that can be performed on the database（）
