SQL-5 In-Class Exercise Answer IST 210 Organization of Data IST2101

Review Questions of Previous Class Q1. Show the total hours worked for project with ID 1200 (from assignment table) Q2. Count how many distinct departments in project table IST2102

3 /* Q1. Show the total hours worked for project with ID 1200 (from assignment table) */ SELECT SUM(HoursWorked) FROM ASSIGNMENT WHERE ProjectID = 1200; /* Q2. Count how many distinct departments in project table */ SELECT COUNT(distinct Department) FROM PROJECT;

Review Questions of Previous Class Q3. Group projects by departments. Show department names and number of projects associated with each department Q4. Add a constraint to Q3. Only show the departments with number of projects more than 1 IST2104

5 /* Q3 Group projects by departments. Show department names and number of projects associated with each department */ SELECT Department, COUNT(*) FROM PROJECT GROUP BY Department; /* Q4 Add a constraint to Q3. Only show the departments with number of projects more than 1 */ SELECT Department, COUNT(*) FROM PROJECT GROUP BY Department HAVING COUNT(*) > 1;

Exercise 1 IST2106 Show the names of employees who is assigned to ProjectID 1000 – First write two separate queries and then merge into one query 6 Q2. Show the names of employees with the employee numbers from Q1 Q1. Find employee numbers who is assigned to projectID 1000 EMPLOYEE ASSIGNMENT

7 /*** Exercise 1: Show the names of employees who is assigned to ProjectID 1000 ***/ /* Q1. Find employee numbers who is assigned to projectID 1000 */ SELECT EmployeeNumber FROM ASSIGNMENT WHERE ProjectID = 1000; /* Q2. Show the names of employees with the employee numbers from Q1 */ SELECT FirstName, Lastname FROM EMPLOYEE WHERE EmployeeNumber IN (1,8,10); /* Use subquery to answer exercise 1 */ SELECT FirstName, Lastname FROM EMPLOYEE WHERE EmployeeNumber IN (SELECT EmployeeNumber FROM ASSIGNMENT WHERE ProjectID = 1000);

Exercise 1: use join Show the names of employees who is assigned to ProjectID 1000 IST2108 Shared column: EmployeeNumber

9 /* Use join to answer exercise 1 */ SELECT FirstName, Lastname FROM EMPLOYEE AS E, ASSIGNMENT AS A WHERE E.EmployeeNumber = A.EmployeeNumber AND A.ProjectID=1000;

Exercise 2 Show the project names assigned to EmployeeNumber 4 IST21010 ASSIGNMENT PROJECT

IST21011 /*** Exercise 2: Show the project names assigned to EmployeeNumber 4 ***/ /* Q1. ProjectIDs assigned to Employee Number 4 */ SELECT ProjectID FROM ASSIGNMENT WHERE EmployeeNumber = 4; /* Q2. Project names with project IDs from Q1 */ SELECT ProjectName FROM PROJECT WHERE ProjectID IN (1100, 1200, 1400); /* Use subquery to answer exercise 2 */ SELECT ProjectName FROM PROJECT WHERE ProjectID IN (SELECT ProjectID FROM ASSIGNMENT WHERE EmployeeNumber = 4);

Exercise 2: use join Show the project names assigned to EmployeeNumber 4 IST21012 Shared column: ProjectID

IST21013 /* Use join to answer exercise 2 */ SELECT ProjectName FROM PROJECT AS P, ASSIGNMENT AS A WHERE P.ProjectID = A.ProjectID AND A.EmployeeNumber=4;

Exercise 3 Show all the project names that are assigned to Ken – Write 3 separate queries first and then merge them into 1 IST21014 ASSIGNMENT PROJECT 3. Names of the projects with ID in (1000, 1300) 1. Employee numbers with first name as Ken: 10 EMPLOYEE 2. ProjectID assigned to employee number 10: 1000, 1300

IST21015 /* use subquery to answer exercise 3*/ SELECT ProjectName FROM PROJECT WHERE ProjectID IN (SELECT ProjectID FROM ASSIGNMENT WHERE EmployeeNumber IN (SELECT EmployeeNumber FROM EMPLOYEE WHERE FirstName = 'Ken' ) );

Exercise 3: Use Join Show all the project names that are assigned to Ken – Use join IST21016 Shared column: ProjectIDShared column: EmployeeNumber

IST21017 /* use join to answer exercise 3*/ SELECT ProjectName FROM EMPLOYEE AS E, PROJECT AS P, ASSIGNMENT AS A WHERE E.EmployeeNumber = A.EmployeeNumber AND P.ProjectID = A.ProjectID AND E.FirstName='Ken';