Examine the data in the EMPLOYEES and DEPARTMENTS tables:Also examine the SQL statements that create the EMPLOYEES and DEPARTMENTS tables:On the EMPLOYEES table, EMPLOYEE_ID is the primary key.MGR_ID is the ID of managers and refers to the EMPLOYEE_ID.DEPT_ID is foreign key to DEPARTMENT_ID column of the DEPARTMENTS table.On the DEPARTMENTS table, DEPARTMENT_ID is the primary key.Examine this DELETE statement:What happens when you execute the DELETE statement?()
A. Only the row with department ID 40 is deleted in the DEPARTMENTS table.
B. The statement fails because there are child records in the EMPLOYEES table with department ID 40.
C. The row with department ID 40 is deleted in the DEPARTMENTS table. Also the rows with employee IDs 110 and 106 are deleted from the EMPLOYEES table.
D. The row with department ID 40 is deleted in the DEPARTMENTS table. Also the rows with employee IDs 106 and 110 and the employees working under employee 110 are deleted from the EMPLOYEES table.
E. The row with department ID 40 is deleted in the DEPARTMENTS table. Also all the rows in the EMPLOYEES table are deleted.
F. The statement fails because there are no columns specifies in the DELETE clause of the DELETE statement.
第1题:
( 2 )现有如下两个关系模式:
Employees ( Eid , Name , DeptNO )
Departments ( DeptNO , DeptName , TotalNumber )
Employees 关系模式描述了职工编号、姓名和所在部门编号; Departments 关系模式描述了部门编号、名称和职工总人数。
请 按 SQL Serve r 所采用 的 Tansact — SQ L 语法格式编写实现具有功能的后触发型触发器 : 每当在Employee s表中插入一行数据时,相应部门的职工总人数就加 1 。( 10 分)
第2题:
已知关系模式R的全部属性集U={A,B,C,D,E,G}及函数依赖集:
F=(AB→C,C→A,BC→D,ACD→B,D→EG,BE→C,CG→BD,CE→AG}求属性集闭包(BD)+
(2) 现有如下两个关系模式:
Employees(Eid,Name,DeptNO)
Departments(DeptNO,DeptName,TotalNumber)
Employees关系模式描述了职工编号、姓名和所在部门编号;Departments关系模式描述了部门编号、名称和职工总
第3题:
Nothing in these Rules shall ______ any vessel,or the owner,master or crew thereof,from the consequences of any precaution which may be required by the ordinary practice of seaman,or by the special circumstances of the case.
A.exonerate
B.exhaust
C.exercise
D.examine
第4题:
第5题:
检查
A.expect
B.except
C.excuse
D.examine
第6题: