Class 9: Database Management Systems July 21 st, 2011

 Looks great!  Google analytics… now what?  I want you to check Google analytics and see who is visiting your Web site.  At the end of the semester, we’ll see who has the most visitors!  How do I get people to my site: see SEO slides; submit to Google, yahoo.

 Visio stencil on my Web site for ER diagrams

 List a few current events in information systems news  Construct and ER diagram (Recap)  Use vLookup in excel to mimic a relational database  Convert an ER diagram to a relational database scheme

 Twinkle Tones School of Music provides private lessons only by musician request. When a musician requests a private lesson, the School finds an available instructor and arranges a lesson schedule.  The School would like to track these lessons – the day of the week when they are scheduled, as well as the time they begin.  The School would also like to track musician names and addresses, as well as instructor names and addresses.

INSTRUCTORSMusicians teach LESSONS MusID MusName Mus InsID Ins InsName TimeDay [0:M] [1:1]

TEAMS Aggregate STUDENTSTEACHERS [2:5][1:1] [0:M][1:3] TeamId TeamName StudentId Name TeacherId

 We can use the entity relationship diagrams we design to create relational tables that can be stored in a database.  NOTE: A relational database is not just a table of information. It consists of multiple tables that reference one another.

 Let’s mimic one together in Excel and vLookup  Download excel sheet from: _summer2011/example%20data.xlsx

Desktop My Documents My Network Places MIS 111CMIMy Pictures July 13.ppt Class Roster. doc

 In the 1960s, a man working for IBM decided that he could improve upon hierarchical data storage.  He knew that the hierarchical model led to data redundancy and confusion.  We always have to start at the top node. That makes looking for the data I need take forever!  Sometimes I end up with the same data saved in different places! If I need to update that data, I need to do it in multiple places!

 1 st normal form (Rule 1)  No repeating elements or groups of elements Take from

 2 nd normal form (Rule 2)  No partial dependencies on a concatenated key Take from

 3 rd normal form (Rule 3)  No dependencies on non-key attributes Take from

 ER diagrams were developed a few years after Codd  If the ER diagram was developed correctly, we are automatically in 3 rd Normal Form!!!

 We call this in general a “many-to-many” relationship because each entity class may have more than one instance.  Many-to-many = [M:N] [0:30] STUDENTSCOURSES enroll in [4:6]

 We call this in general a “one-to-many” relationship because one side may only have up to one instance and the other may have many.  One-to-Many = [1:M] COURSES TEACHERS teach [0:1] [1:3]

 We call this in general a “one-to-one” relationship because both entity classes may only have a maximum of one instance.  One-to-one = [1:1] DOCTORSPATIENTS treat [1:1]

 Remember this? STUDENTS COURSES enroll in CourseNo CourseName StudentName Student TEACHERS teach TeacherID TeacherName Teacher TeacherSalary StudentID [0:1] [1:3] [0:30] [4:6]

 1. For every strong entity class, create a table or relation.  The identifier becomes what is called a primary key.  The other attributes become what are called non-key elements.  We can represent the STUDENTS table as such: STUDENTS (StudentID, StudentName, Student )

 1. For every strong entity class, create a table or relation.  The identifier becomes what is called a primary key.  The other attributes become what are called non-key elements. COURSES (CourseNo, CourseName)

 1. For every strong entity class, create a table or relation.  The identifier becomes what is called a primary key.  The other attributes become what are called non-key elements. TEACHERS (TeacherID, TeacherName, Teacher , TeacherSalary)

 TEACHERS (TeacherID, TeacherName, Teacher , TeacherSalary)  STUDENTS (StudentID, StudentName, Student )  COURSES (CourseNo, CourseName)

StudentIDStudentNameStudent CourseNoCourseName MIS111CMP_INTRNTWKD MIS373SYSTM_ANL_DSGN MIS696ARDNGS_IN_MIS TeacherIDTeacherNameTeacher TeacherSalary

 2. Locate any [1:M] relationships between strong entity classes. STUDENTS COURSES enroll in CourseNo CourseName StudentName Student TEACHERS teach TeacherID TeacherName Teacher TeacherSalary StudentID [0:1] [1:3] [0:30] [4:6]

 2. Locate any one-to-many relationships between strong entity classes. Put the primary key on the “1” side of the relationship into the table of the “M” side. TEACHERS (TeacherID, TeacherName, Teacher , TeacherSalary) COURSES (CourseNo, CourseName, TeacherID)

 “TeacherID” is now a foreign key in the COURSES table. CourseNoCourseNameTeacherID MIS111CMP_INTRNTWKD23489 MIS373SYSTM_ANL_DSGN13445 MIS696ARDNGS_IN_MISNULL TeacherIDTeacherNameTeacher TeacherSalary

 3. Locate any many-to-many relationships. Create a completely new table to represent this relationship. Use the primary keys of the participating entity classes as a new combined primary key. We now have THREE tables instead of two. COURSES (CourseNo, CourseName, TeacherID) STUDENTS (StudentID, StudentName, Student ) STUDENTS_COURSES (StudentID, CourseID)

CourseNoCourseNameTeacherID MIS111CMP_INTRNTWKD23489 MIS373SYSTM_ANL_DSGN13445 MIS696ARDNGS_IN_MISNULL TeacherIDTeacherNameTeacher TeacherSalary StudentIDStudentNameStudent StudentIDCourseNo MIS MIS MIS111

 STUDENTS (StudentID, StudentName, Student )  TEACHERS (TeacherID, TeacherName, Teacher )  COURSES (CourseNo, CourseName, TeacherID)  STUDENTS_COURSES (StudentID, CourseNo)

PUPPIESSTORES CUSTOMERS buy sell StoreID StoreName StoreLoc PupAgeWhenSold PupBreed PupTemp PupID CustZip CustName CustGender CustID [1:1][1:M] [0:1] [1:M]

 1. For every strong entity class, create a table or relation.  2. Locate any [1:M] relationships between strong entity classes. Put the primary key on the “1” side of the relationship into the table of the “M” side.  3. Locate any [M:N] relationships. Create a completely new table to represent this relationship. Use the primary keys of the participating entity classes as a new combined primary key.

 PUPPIES (PupID, PupBreed, PupTemp, PupAgeWhenSold, StoreID, CustID)  STORES (StoreID, StoreName, StoreLoc)  CUSTOMERS (CustID, CustName, CustGender, CustZip)

StoreIDStoreNameStoreLoc 1Puppies ‘R’ USTucson 4Pup PlacePhoenix CustIDCustNameCustGenderCustZip 2XavierM MarthaF BillM85719 PupIDPupBreedPupTempPupAgeWhenSoldStoreIDCustID 3dalmatianactive8412 4beaglesweet1012 7laboradorsweet7412 8shih-tzuactive8410

INSTRUCTORSMUSICIANS teach LESSONS MusID MusName Mus InsID Ins InsName TimeDay [0:M] [1:1] MusInst

 4. Locate any one-to-one relationships between entity classes. Take the primary key from one side of the relationship and place it in the table of the other entity class. INSTRUCTORS (InsID, InsName, Ins , MusID) MUSICIANS (MusID, MusName, Mus , MusInst) INSTRUCTORS (InsID, InsName, Ins ) MUSICIANS (MusID, MusName, Mus , MusInst, InsID) OR

 5.For weak entity classes, create a new table or relation and add its attributes. Then, add the primary key from its corresponding strong entity class. Combine all attributes to create a new primary key. LESSONS (Day, Time, MusID, InsID)

 Convert this ERD into a set of relational tables. DOCTORSPATIENTS TREATMENTS treat [1:1] [0:M] DocID DocName PatName PatID Prscrpt Date

 5.For weak entity classes, create a new table or relation and add its attributes. Then, add the primary key from its corresponding strong entity class. Combine all attributes to create a new primary key. DOCTORS (DocID, DocName) PATIENTS (PatID, PatName, DocID) TREATMENTS (Date, Prscrpt, PatID, DocID)

 6. Treat aggregates just like strong entity classes. Create a table or relation.  The identifier becomes what is called a primary key.  The other attributes become what are called non-key elements.  7. Treat the aggregation as its own relationship and add foreign keys accordingly.

TEAMS Aggregate STUDENTS TEACHERS [2:5] [1:1] [0:M][1:3] TEAMS (TeamID, TeamCaptain, FormationDate, TeacherID) TEAMS_STUDENTS (StudentID, TeamID)

 Quiz  Tomorrow:  I will give you / post your assignment Paper or Visio (preferred). Stencils are on the Web site  You’ll have the rest of the class time to work on it (individual assignment). This will be due beginning of class next Wednesday.  I will be able to answer “general” questions.