Name: Sample Answers Q.2(c) 7 7

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1 p.1 of 11 INFS 4240 (Section B) Database Management Systems Fall 2017 Practice for Test 2 (not for credit, but to help you prepare) Time allowed: 1 hour 15 minutes Q.1(a) Q.1(b) Q.1(c) Q.1(d) Q.1(e) Q.1(f) Q.1(g) Q.2(a) 7 7 Q.2(b) 7 7 Name: Sample Answers Q.2(c) 7 7 Open Book, Open Notes, including web access. Consultation with other people not allowed. Answer all questions. Answer in the space provided. Please give a good effort to make your writing readable. Q.2(d) 7 7 Total Read each of the questions carefully before working on it.

2 p.2 of 11 Q.1 We have designed a simple personnel database for a certain company with 40 employees in 4 departments. The four departments are: Executive, Accounting, Sales, and Engineering. The personnel database consists of three tables, with the schema illustrated in the following, and explanation below. Department( DeptNo, DeptName ). Employee( EmpNo, EmpName, Salary, DeptNo, ReportsTo ). Commission( EmpNo, OrderNo, Amount ). The Department table has 2 columns: DeptNo is a unique number to identify the department and it is the primary key; DeptName is the department name. The other table is the Employee table with 5 columns: EmpNo is a unique number to identify the employee and it is the primary key; EmpName is the name of the employee; Salary is employee s salary in dollars; DeptNo is the department number indicating the department the employee belongs to, therefore serving as foreign key to the Department table. (Every employee must belong to exactly one department. Null value is not allowed.) ReportsTo is the employee number (EmpNo) of the employee this employee reports to, serving as foreign key to the same Employee table. (Every employee reports to exactly one other employee in the company except the CEO, who does not report to anyone. Therefore, null is allowed, indicating the CEO not reporting to any other employee.) Employees of the Sales Department may also get commission pay for their work in getting customer orders. The Commission table keeps track of that; the table has 3 columns. EmpNo is a foreign key to the Employee table, identifying an employee; OrderNo identifies the customer order for which the employee gets a commission pay indicated by the Amount column. The primary key for the Commission table consists of two columns: both EmpNo and OrderNo. We are provided with access to the database, for both MS Access and Oracle. If you want to use MS Access, copy the file at P:\wu\4240B\T2\Q1Emp.accdb to your computer. The database file contains the tables Department, Employee, and Commission for your use. If you use Oracle, sign on with SQL*Plus using your user-id@infs4240 and your password. You can refer to these tables as wu.department, wu.employee, and wu.commission in your SQL statements. Answer the following questions Q.1(a) to Q.1(g). [Q.1(a) 12 points, 10 points each for the rest; 72 points total]

3 p.3 of 11 Q.1(a) The following is the SQL statement which created the Department table: Create table Department (DeptNo Number Primary Key, DeptName Text not null ); Write the two SQL statements which created the other two tables Employee and Commission, with the appropriate constraints as specified above. You may assume these datatypes (or domain names) as appropriate for the respective columns: Number for EmpNo and OrderNo, Text for EmpName, Currency for Salary and also for Amount. Do not forget to specify the Primary Key for each table, and the Foreign Keys, if any. (12 points) Create table Employee (EmpNo Number Primary Key, EmpName Text, Salary Currency, DeptNo Number not null references Department(DeptNo), ReportsTo Number references Employee(EmpNo) ); Create table Commission (EmpNo Number references Employee(EmpNo), OrderNo Number, Amount Currency, Primary Key (EmpNo, OrderNo) ); Q.1(b) Write an SQL query to list all employees of the Accounting Department: list both EmpNo and EmpName. Order the result by EmpName. Write down the SQL statement below, using the condition (DeptName = Accounting ). (10 points) Select EmpNo, EmpName from Employee e, Department d where e.deptno=d.deptno AND DeptName= Accounting order by EmpName; EmpNo Q1b EmpName 112 Bruce 97 Gina 23 Kevin 64 Mary 21 Nick 59 Teresa

4 p.4 of 11 Q.1(c) Write two SQL statements to find the employees paid at the highest salary in the company. Write an SQL statement first to find the highest salary pay. Then write another SQL statement to list all the employees paid at that highest salary: list the Employee Name (EmpName), the Employee Number (EmpNo), the Employee s Department (DeptName) and the salary (Salary). List the result in alphabetical order of the employee name (EmpName). Write down the two SQL statements below. Alternatively, we may also write that into one SQL statement using a sub-query. (10 points) Select max(salary) from Employee; that gives us 80,000. Select EmpName, EmpNo, DeptName, Salary from Employee e, Department d where e.deptno=d.deptno AND Salary = order by EmpName; In one SQL statement using a sub-query Select EmpName, EmpNo, DeptName, Salary from Employee e, Department d where e.deptno=d.deptno AND Salary = (select max(salary) from Employee) order by EmpName; Q1c EmpName EmpNo DeptName Salary Matthew 33 Sales $80, Robert 1 Executive $80, Q.1(d) Write an SQL statement to list the number of employees, and the maximum and minimum salaries in each department: list the Department (DeptName), number of employees, the maximum salary and the minimum salary in the department. Write down the SQL statement below, (10 points) Select DeptName, count(empno), max(salary), min(salary) from Employee e, Department d where e.deptno=d.deptno group by DeptName; DeptName Q1d CountOfEmpNo MaxOfSalary MinOfSalary Accounting 6 $62, $32, Engineering 9 $65, $48, Executive 5 $80, $71, Sales 20 $80, $28,000.00

5 p.5 of 11 Q.1(e) Write an SQL statement to list the department along with the number of employees with salary less than $50,000 in each department. List the department name (DeptName), and the number of people (ie, the number of employees at salary less than $50,000). Write down the SQL statement below. (10 points) Select DeptName, count(empno) from Employee e, Department d where e.deptno=d.deptno AND salary < group by DeptName; DeptName Q1e CountOfEmpNo Accounting 4 Engineering 1 Sales 15 Q.1(f) An employee may get Commission Pay on top of his/her salary whenever he/she has helped to get a Sales Order. Every time any employee gets involved in getting a Sales Order, the Commission table keeps track of the commission pay amount for the employee. An employee named Jim has been involved in several Sales Orders. Write an SQL statement to determine the total commission pay for Jim. (Hint: Use where EmpName= Jim and apply the aggregate functions SUM and COUNT.) List the total commission amount, and the number of Sales Orders Jim helped to get. (10 points) Select sum(c.amount), count(c.orderno) from Employee e inner join Commission c on e.empno=c.empno where e.empname = Jim ; SumOfAmount Q1f CountOfOrderNo $2,

6 p.6 of 11 Q.1(g) Who is Jim s manager? that is, whom does Jim report to? Write an SQL statement to list the employee name Jim along with the name of Jim s manager that is, the person Jim reports to. List the employee name (EmpName), along with the employee name (EmpName) of the manager. (10 points) Select e.empname, m.empname from Employee e, Employee m where e.reportsto=m.empno AND e.empname = Jim ; Jim e.empname Q1g m.empname Matthew

7 p.7 of 11 Q.2 We used two SQL statements to create two tables COMPOSER and PIECE. The two SQL statements are listed below: create table COMPOSER (CNo number(4) not null primary key, CName varchar2(16) not null, Born number(4), Died number(4) ); create table PIECE (PNo number(4) not null, PName char(32) not null, CNo references COMPOSER(CNo) on delete cascade, Primary Key (PNo) ); These are standard SQL statements which will work in Oracle. If the tables are created in MS Access, we will need to set up the relationship between the tables to correctly enforce Referential Integrity. We proceeded to load the two tables with data. The following illustrates the tables with all the data records we have inserted: COMPOSER CNo CName Born Died 1 Vivaldi Bach Mozart Dvorak Prokofiev PIECE PNo PName CNo 1001 The Four Seasons B-Minor Mass Christmas Oratorio Missa Solemnis Classical Symphony Cinderella 5 Base on these two tables of data, answer the questions Q.2(a) to Q.2(d). [7 points each; 28 points total.]

8 p.8 of 11 Q.2(a) Will the following SQL insert statement execute successfully without error? Complete the tables below by filling in inserted entries, if any, to show the results after the execution of the following SQL insert statement. (7 points) insert into PIECE values (1014, New World Symphony, 4); Will the above SQL insert statement execute without error? (Yes or No) YES If your answer is NO, what error message do we get? Explain the error message by indicating what is wrong with the data in the tables in our database. If your answer is YES, fill in any new entries below to show the result after execution, to indicate any change. COMPOSER CNo CName Born Died 1 Vivaldi Bach Mozart Dvorak Prokofiev PIECE PNo PName CNo 1001 The Four Seasons B-Minor Mass Christmas Oratorio Missa Solemnis Classical Symphony Cinderella New World Symphony 4

9 p.9 of 11 Q.2(b) Will the following SQL insert statement execute successfully without error? Complete the tables below by filling in inserted entries, if any, to show the results after the execution of the following SQL insert statement. (7 points) insert into PIECE values (1017, Database Symphony, 6); Will the above SQL insert statement execute without error? (Yes or No) NO If your answer is NO, what error message do we get? Explain the error message by indicating what is wrong with the data in the tables in our database. Foreign Key violation: Foreign Key CNo=6 becomes dangling reference since there is no record in COMPOSER (referenced table) with CNo=6. The insertion SQL command is not executed. If your answer is YES, fill in any new entries below to show the result after execution, to indicate any change. COMPOSER CNo CName Born Died 1 Vivaldi Bach Mozart Dvorak Prokofiev PIECE PNo PName CNo 1001 The Four Seasons B-Minor Mass Christmas Oratorio Missa Solemnis Classical Symphony Cinderella 5

10 p.10 of 11 Q.2(c) Will the following SQL delete statement execute successfully without error? Complete the tables below by crossing out any deleted entries, if any, to show the results after the execution of the following SQL delete statement. (7 points) delete from PIECE where CNo = 3; Will the above SQL delete statement execute without error? (Yes or No) YES If your answer is NO, what error message do we get? Explain the error message by indicating what is wrong with the data in the tables in our database. If your answer is YES, cross out any entries below to show the result after execution, to indicate any change. COMPOSER CNo CName Born Died 1 Vivaldi Bach Mozart Dvorak Prokofiev PIECE PNo PName CNo 1001 The Four Seasons B-Minor Mass Christmas Oratorio Missa Solemnis Classical Symphony Cinderella 5

11 p.11 of 11 Q.2(d) Will the following SQL delete statement execute successfully without error? Complete the tables below by crossing out any deleted entries, if any, to show the results after the execution of the following SQL delete statement. (7 points) delete from COMPOSER where CName = Bach ; Will the above SQL delete statement execute without error? (Yes or No) YES If your answer is NO, what error message do we get? Explain the error message by indicating what is wrong with the data in the tables in our database. If your answer is YES, cross out any entries below to show the result after execution, to indicate any change. COMPOSER CNo CName Born Died 1 Vivaldi Bach Mozart Dvorak Prokofiev PIECE PNo PName CNo 1001 The Four Seasons B-Minor Mass Christmas Oratorio Missa Solemnis Classical Symphony Cinderella 5 - End of PracticeTest 2 -