有关当事人约定由债务人向第三人履行债务的，下列的说法中正确的有()。

A．A.SELECT empno,ename FROM empWHERE empno=(SELECT empno FROM dept WHERE dname="研发部")

B．B.SELECT empno,ename FROM empWHERE deptno=(SELECT deptno FROM dept WHERE dname='研发部')

C．C.SELECT empno,ename FROM empWHERE deptno=(SELECT * FROM dept WHERE dname='研发部')

D．D.SELECT empno,ename FROM deptWHERE deptno=(SELECT deptno FROM emp WHERE dname="研发部")

A、select level,ename,empno,mgr from emp connect by prior empno=mgr and ename<>'JONES' start with ename ='KING'；

B、select level,ename,empno,mgr from emp connect by prior empno=mgr and ename='JONES' start with ename ='KING'；

C、select level,ename,empno,mgr from emp connect by prior empno=mgr and ename<>'JONES' start with ename <>'KING'；

D、select level,ename,empno,mgr from emp connect by prior empno=mgr and ename='JONES' start with ename <>'KING'；

A、select ename from emp connect by prior empno=mgr start with ename='JONES';

B、select ename from emp where ename<>'JONES' connect by prior empno=mgr start with ename='JONES';

C、select ename from emp where ename='JONES' connect by prior empno=mgr start with ename='JONES';

D、select ename from emp where ename='JONES' connect by prior empno=mgr start with ename<>'JONES';

在员工管理系统中，需要建立员工表（emp），字段有员工编号（EMPNO）、姓名（ENAME）、工作（JOB）、经理编号（MGR）、雇佣日期（HIREDATE）、工资（SAL）、提成（COMM）、部门编号（DEPTNO），数据示例如下表所示。现要求使用JDBC数据库连接技术，实现根据员工编号查询、修改和删除员工记录，添加员工信息。

A. Select * From Emp Where EmpNO Not In('791','792','793')

B. Select * From Emp Where EmpNO !='791' AND EmpNO!='792' And EmpNO='793'

C. Select * From Emp Where EmpNO<>'791' AND EmpNO<>792' And EmpNO=<>793'

D. Select * From Emp Where EmpNO =!'791' AND EmpNO =!'792' And EmpNO =!'793'

A．v_ename ename %type

B．v_ename emp.ename %type

C．v_ename emp.ename type

D．v_ename emp.ename %rowtype

A. CREATE TABLE EMP (empno NUMBER(4), ename VARCNAR2(35), deptno NUMBER(7,2) NOT NULL CONSTRAINT emp_deptno_fk FOREIGN KEY deptno REFERENCES dept deptno);

B. CREATE TABLE EMP (empno NUMBER(4), ename VARCNAR2(35), deptno NUMBER(7,2) CONSTRAINT emp_deptno_fk REFERENCES dept (deptno));

C. CREATE TABLE EMP (empno NUMBER(4) ename VARCHAR2(35), deptno NUMBER(7,2) NOT NULL, CONSTRAINT emp_deptno_fk REFERENCES dept (deptno) FOREIGN KEY (deptno));

D. CREATE TABLE EMP (empno NUMBER(4), ename VARCNAR2(35), deptno NUMBER(7,2) FOREIGN KEY CONSTRAINT emp deptno fk REFERENCES dept (deptno));

A. Select * From Emp Where EmpNO In('791','792','793')

B. Select * From Emp Where EmpNO ='791' Or EmpNO='792' OR EmpNO='793'

C. Select * From Emp Where EmpNO >='791' And EmpNO<='793'd. select * from emp where empno >'791' And EmpNO<'793'