Chapter 9 Structured Query Language David M. Kroenke Database Processing © 2000 Prentice Hall

Chapter 9 © 2000 Prentice Hall SQL “Structured Query Language; standard language for relational data manipulation” DB2, SQL/DS, Oracle INGRES, SYBASE, SQL Server dBase/Win, Paradox, Access Page 217

Chapter 9 © 2000 Prentice Hall Introduction to SQL IBM in the mid-1970s as SEQUEL SQ92 = 1992 ANSI standard data access language that is embedded in application programs result of an SQL statement is a relation Page 217

Sample Data Figure 9-2 © 2000 Prentice Hall

Chapter 9 © 2000 Prentice Hall Projection SELECT SID, Name, Major FROM STUDENT Page 219

Chapter 9 © 2000 Prentice Hall Selection SELECT SID, Name, Major, GradeLevel, Age FROM STUDENT WHERE Major = ‘MATH’ Page 220

Chapter 9 © 2000 Prentice Hall Selection SELECT * FROM STUDENT WHERE Age Between 19 and 30 Page 222

Chapter 9 © 2000 Prentice Hall Sorting SELECT Name, Major, Age FROM STUDENT WHERE Major = ‘ACCOUNTING’ ORDER BY Name Page 223

Chapter 9 © 2000 Prentice Hall SQL Built-In Functions SELECT COUNT(Major) FROM STUDENT Page 223

Chapter 9 © 2000 Prentice Hall Grouping SELECT Major, COUNT(*) FROM STUDENT GROUP BY Major HAVING COUNT(*) > 1 Page 224

Chapter 9 © 2000 Prentice Hall Querying Multiple Tables Retrieval Using Subquery Joining with SQL Page 226

Chapter 9 © 2000 Prentice Hall Subquery (the second SELECT) SELECT Name FROM STUDENT WHERE SID IN (SELECT StudentNumber FROM ENROLLMENT WHERE ClassName = ‘BD445’) Page 226

Chapter 9 © 2000 Prentice Hall Joining with SQL SELECT STUDENT.SID, STUDENT.Name, ENROLLMENT.ClassName FROM STUDENT, ENROLLMENT WHERE STUDENT.SID = ENROLLMENT.StudentNumber Page 227

Chapter 9 © 2000 Prentice Hall Outer Join SELECT Name, ClassName FROM STUDENT LEFT JOIN ENROLLMENT ON SID = StudentNumber; (note semicolon notation) Page 230

Chapter 9 © 2000 Prentice Hall Exists and Not Exists “Logical operators whose value is either true or false depending on the presence or absence of rows that fit the qualifying conditions” Page 230

Chapter 9 © 2000 Prentice Hall Exist SELECT DISTINCT StudentNumber FROM ENROLLMENT A WHERE EXISTS (SELECT * FROM ENROLLMENT B WHERE A.StudentNumber = B.StudentNumber AND A.ClassName NOT = B.ClassName) Page 230

Chapter 9 © 2000 Prentice Hall Changing Data Inserting Data INSERT INTO ENROLLMENT VALUES (400, ‘BD445’, 44) Deleting Data DELETE STUDENT WHERE STUDENT.SID = 100 Modifying Data UPDATE ENROLLMENT SET PositionNumber = 44 WHERE SID = 400 Page 232