1. MGS4020_09.ppt/Jul 5, 2016/Page 1 Georgia State University - Confidential MGS 4020 Business Intelligence Relational Algebra and Structured Query Language Jul 5, 2016

2. MGS4020_09.ppt/Jul 5, 2016/Page 2 Georgia State University - Confidential Agenda JoinSQLQueries

3. MGS4020_09.ppt/Jul 5, 2016/Page 3 Georgia State University - Confidential Set Operations Restriction UnionIntersection Difference Projection Binary UNION ?? Unary

4. MGS4020_09.ppt/Jul 5, 2016/Page 4 Georgia State University - Confidential SQL Building Blocks CREATE, ALTER, DROP INSERT, DELETE, UPDATE SELECT UNION, INTERSECT, MINUS JOIN INDEX VIEWS Utilities (introduced throughout the examples). Transaction Management Features Additional Features

5. MGS4020_09.ppt/Jul 5, 2016/Page 5 Georgia State University - Confidential Horizontal Slices Restriction –Specifying Conditions  Unconditional List all students select* fromSTUDENT; (Student)  Conditional List all student with GPA > 3.0 select* fromSTUDENT whereGPA > 3.0; GPA > 3.0 (Student) Algebra: selection or restriction (R)

6. MGS4020_09.ppt/Jul 5, 2016/Page 6 Georgia State University - Confidential Pattern Matching ‘%’any string with n characters, n>=0 ‘_’any single character. x exact sequence of string x. List all CIS 3200 levelcourses. select* fromCOURSE wherecourse# like ? ; List all CIS courses. select* fromCOURSE wherecourse# like CIS%’;

7. MGS4020_09.ppt/Jul 5, 2016/Page 7 Georgia State University - Confidential Specifying Conditions List all students in... select* fromSTUDENT wherecity in (‘Boston’,’Atlanta’); List all students in... select* fromSTUDENT wherezip not between 60115 and 60123;

8. MGS4020_09.ppt/Jul 5, 2016/Page 8 Georgia State University - Confidential Vertical Slices Projection –Specifying Elements  No Specification List all information about Students select* fromSTUDENT; (Student)  Conditional List IDs, names, and addresses of all students selectID, name, address fromSTUDENT; ID, name, address (Student) Algebra: projection (R)

9. MGS4020_09.ppt/Jul 5, 2016/Page 9 Georgia State University - Confidential Does SQL treat Relations as ‘Sets’ What are the different salaries we pay to our employees? selectsalary fromEMPLOYEE; OR is the following better? selectDISTINCT salary fromEMPLOYEE; Is the following necessary?

10. MGS4020_09.ppt/Jul 5, 2016/Page 10 Georgia State University - Confidential Horizontal and Vertical Query: Lista all student ID, names and addresses who have GPA > 3.0 and age >20. selectID, Name, Address fromSTUDENT whereGPA > 3.0 and DOB < ‘1-Jan-6’ order byName DESC; Algebra: ID,name, address ( GPA > 3.0 and DOB < ‘1-Jan-74’ (STUDENT) Order by sorts result in descending (DESC) order. Note: The defauld order is ascending (ASC) as in: order by Name;

11. MGS4020_09.ppt/Jul 5, 2016/Page 11 Georgia State University - Confidential Agenda SQLJoinQueries

12. MGS4020_09.ppt/Jul 5, 2016/Page 12 Georgia State University - Confidential Relational Database A relational database is a collection of data items organized as a set of formally-described tables from which data can be accessed or reassembled in many different ways without having to reorganize the database tables. The relational database was invented by E. F. Codd at IBM in 1970.databasedata The standard user and application program interface to a relational database is the structured query language (SQL). SQL statements are used both for interactive queries for information from a relational database and for gathering data for reports.SQL A relational database is a set of tables containing data fitted into predefined categories. Each table (which is sometimes called a relation) contains one or more data categories in columns. Each row contains a unique instance of data for the categories defined by the columns. For example, a typical business order entry database would include a table that described a customer with columns for name, address, phone number, and so forth. Another table would describe an order: product, customer, date, sales price, and so forth. A user of the database could obtain a view of the database that fitted the user's needs. For example, a branch office manager might like a view or report on all customers that had bought products after a certain date. A financial services manager in the same company could, from the same tables, obtain a report on accounts that needed to be paid.

13. MGS4020_09.ppt/Jul 5, 2016/Page 13 Georgia State University - Confidential Relational Database When creating a relational database, you can define the domain of possible values in a data column and further constraints that may apply to that data value. For example, a domain of possible customers could allow up to ten possible customer names but be constrained in one table to allowing only three of these customer names to be specifiable. The definition of a relational database results in a table of metadata or formal descriptions ofmetadata the tables, columns, domains, and constraints. Meta is a prefix that in most information technology usages means "an underlying definition or description." Thus, metadata is a definition or description of data and metalanguage is a definition or description of language. A database is a collection of data that is organized so that its contents can easily be accessed, managed, and updated. The most prevalent type of database is the relational database, a tabular database in which data is defined so that it can be reorganized and accessed in a number of different ways. A distributed database is one that can be dispersed or replicated among different points in a network. An object-oriented programming database is one that is congruent with the data defined in object classes and subclasses.datarelational databaseobject-oriented programming SQL (Structured Query Language) is a standard interactive and programming language for getting information from and updating a database. Although SQL is both an ANSI and an ISO standard, many database products support SQL with proprietary extensions to the standard language. Queries take the form of a command language that lets you select, insert, update, find out the location of data, and so forth.databaseANSIISO

14. MGS4020_09.ppt/Jul 5, 2016/Page 14 Georgia State University - Confidential Nesting Queries SELECTattribute(s) FROMrelation(S) WHEREattr [not] {in | comparison operator | exists } ( query statement(s) ); List names of students who are taking “BA201” select Name from Student whereID in ( selectID fromREGISTRATION where course#=‘BA201’);

15. MGS4020_09.ppt/Jul 5, 2016/Page 15 Georgia State University - Confidential Sub Queries List all students enrolled in CIS courses selectname fromSTUDENT where studentnum in (selectStudentId fromREGISTRATION wherecno like ‘CIS%’); List all students enrolled in CIS courses selectname fromSTUDENT where studentnum in (selectStudentId fromREGISTRATION wherecno like ‘CIS%’); List all courses taken by Student (Id 1011) selectcname fromCOURSE wherecnum _ any (selectcno fromREGISTRATION whereStudentId = 1011);

16. MGS4020_09.ppt/Jul 5, 2016/Page 16 Georgia State University - Confidential Sub Queries Who received the highies grade in CIS 814 selectStudentId fromGRADE wherecnum = ‘CIS 814’ and grade >=all (selectgrade fromGRADE wherecno = ‘CIS 814’); Who received the highies grade in CIS 814 selectStudentId fromGRADE wherecnum = ‘CIS 814’ and grade >=all (selectgrade fromGRADE wherecno = ‘CIS 814’); List all students enrolled in CIS courses. selectname fromSTUDENT S whereexists (select* fromREGISTRATION whereStudentId = S.Studentnum and cno like “CIS%’);

17. MGS4020_09.ppt/Jul 5, 2016/Page 17 Georgia State University - Confidential Recursive Queries List all employees who earn more than their immediate supervisor. selectE.Emp#, E.title, E.salary fromEMPLOYEE, EMPLOYEE M whereE.salary > M.salary and E.ManagerEmp# = M.Wmp#;

18. MGS4020_09.ppt/Jul 5, 2016/Page 18 Georgia State University - Confidential Summaries and Aggregates Calculate the average GPA selectavg. (GPA) from STUDENT, Find the lowest GPAselectmin (GPA) as minGPA from STUDENT, How many CIS majors?selectcount (StudentId) fromSTUDENT wheremajor=‘CIS’; Discarding duplicatesselectavg (distinct GPA) fromSTUDENT where major=‘CIS’

19. MGS4020_09.ppt/Jul 5, 2016/Page 19 Georgia State University - Confidential Aggregate Functions COUNT (attr)- a simple count of values in attr SUM (attr)- sum of values in attr AVG (attr)- average of values in attr MAX (attr)- macimum value in attr MIN (attr)- minimum value in attr  Take effect after data are retrieved from the database  Applied to either the entire resulting relation or groups  Can’t be involved in any query qualifications (where clause) n Would the following query be permitted? selectStudentId fromSTUDENT whereGPA = max (GPA);

20. MGS4020_09.ppt/Jul 5, 2016/Page 20 Georgia State University - Confidential Missing or Incomplete Information List all students whose address or telephone number is missing: select* fromSTUDENT whereAddress is null or GPA is null; Truth Table T T T F F F U U U T F U T F U T F U ~ a a & b a or b

21. MGS4020_09.ppt/Jul 5, 2016/Page 21 Georgia State University - Confidential Groupin Results Obtained Show all students enrolled in each course. selectcno, stno fromREGISTRATION group by cno;Is this grouping OK? Calculate the average GPA of students by county. selectcounty, avg (GPA) as County GPA fromSTUDENT group by county; Calculate the average GPA of each class. selectcno, term, year, count (stno) as enrol fromREGISTRATION group by cno, year, term;

22. MGS4020_09.ppt/Jul 5, 2016/Page 22 Georgia State University - Confidential Selections on Groups n Show all CIS courses that are full. selectcno, count (stno) fromREGISTRATION group by cno havingcount (stno) > 29;

23. MGS4020_09.ppt/Jul 5, 2016/Page 23 Georgia State University - Confidential Union List students who live in Atlanta or GPA > 3.0 selectID, Name, DOB, Address fromSTUDENT where Address = ‘Atlanta’ union selectID, Name, DOB, Address fromSTUDENT where GPA > 3.0; Can we perform a Union on any two Relations ?

24. MGS4020_09.ppt/Jul 5, 2016/Page 24 Georgia State University - Confidential Union Compatibility Two relations, A and B, are union-compatible if 1) A and B contain a same number of attributes, and 2) The corresponding attributes of the two have the same domains Examples CIS=Student (ID: D id ; Name: D name ; Address: D addr ; Grade: D grade ); Senior-Student (SName: D name ; S#: D id ; Home: D addr ; Grade: D grade ); Course (C#: D number ; Title: D str ; Credits: D number ) Are CIS-Student and Senior-Student union compatible? Are CIS-Student and Couse union compatible? What happens if we have duplicate tuples? What will be the column names in the resulting Relation?

25. MGS4020_09.ppt/Jul 5, 2016/Page 25 Georgia State University - Confidential Union, Intersect, Minus selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ UNION selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ UNION selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ INTERSECT selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ INTERSECT selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ MINUS selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; selectCUSTNAME, ZIP fromCUSTOMER where STATE = ‘MA’ MINUS selectSUPNAME, ZIP fromSUPPLIER whereSTATE = ‘MA’ ORDER BY 2; B A B A B AA

26. MGS4020_09.ppt/Jul 5, 2016/Page 26 Georgia State University - Confidential Union, Intersect, Minus

27. MGS4020_09.ppt/Jul 5, 2016/Page 27 Georgia State University - Confidential Agenda SQLJoinQueries

28. MGS4020_09.ppt/Jul 5, 2016/Page 28 Georgia State University - Confidential Connecting/Linking Relations  List information about all students and the classes they are taking What can we use to connect/link Relations? Join: Connecting relations so that relevant tuples can be retrieved. Student Class

29. MGS4020_09.ppt/Jul 5, 2016/Page 29 Georgia State University - Confidential Join Cartesian Product Student: 30 tuples Class: 4 tuples Total Number of Tuples in the Cartesian Product. ? (match each tuple of student to every tuple of class) Select tuples having identical Student Ids. Expected number of such Tuples: Join Selectivity R1R2

30. MGS4020_09.ppt/Jul 5, 2016/Page 30 Georgia State University - Confidential Join Forms General Join Forms –Equijoin –Operator Dependent Natural Join Outer Join –Left –Right –Full selects.*.c.* fromSTUDENT s, CLASS c wheres.ID = c. ID (+); selects.*.c.* fromSTUDENT s, CLASS c wheres.ID = c. ID; = x > y <>... R1R2 R1R2

31. MGS4020_09.ppt/Jul 5, 2016/Page 31 Georgia State University - Confidential Grouping Results after Join Calculate the average GPA of each class selectcourse#, avg (GPA) fromSTUDENT S, CLASS C whereS.ID = C.ID group by course#,

32. MGS4020_09.ppt/Jul 5, 2016/Page 32 Georgia State University - Confidential Index  There is no order among tuples  Indexes speed up data retrieval –Find all students who live in Atlanta. How many tuples would you have to search for this query? What if the table was ‘indexed’? Index TableStudent

33. MGS4020_09.ppt/Jul 5, 2016/Page 33 Georgia State University - Confidential Creating and Deleting Indices CREATE [UNIQUE] INDEX index name ON base-relation-name ( attr-name [order], attr-name[order]...) [CLUSTER]; create unique index student-id on STUDENT ( ID ASC ); create index Address-index on Student (Address); create unique index Name-Age-Index on STUDENT ( Name DESC, Age ); What are the advantages & disadvantages of Indexing?

34. MGS4020_09.ppt/Jul 5, 2016/Page 34 Georgia State University - Confidential Relational Views Relations derived from other relations. Views have no stored tuples. Are useful to provide multiple user views. View 1View 2View N Base Relation 1 Base Relation 2

35. MGS4020_09.ppt/Jul 5, 2016/Page 35 Georgia State University - Confidential View Creation Create View view-name [ ( attr [, attr ]...) ] AS subquery [ with check option ] ; DROP VIEW view-name; –Create a view containing the student ID, Name, Age and GPA for those who are qualified to take 300 level courses, i.e., GPA >=2.0.

36. MGS4020_09.ppt/Jul 5, 2016/Page 36 Georgia State University - Confidential View Options With Check Option enforces the query condition for insertion or update To enforce the GPA >=2.0 condition on all new student tuples inserted into the view A view may be derived from multiple base relations Create a view that includes student IDs, student names and their instructors’ names for all CIS 300 students.

37. MGS4020_09.ppt/Jul 5, 2016/Page 37 Georgia State University - Confidential View Retrieval Queries on views are the same as that on base relations. Queries on views are expanded into queries on their base relations. selectName, Instructor-Name fromCIS300-Student whereName = Instructor-Name; ?

38. MGS4020_09.ppt/Jul 5, 2016/Page 38 Georgia State University - Confidential View: Update Update on a view actually changes its base relation(s)! update Qualified-Student setGPA = GPA-0.1 whereSID = ‘s3’; insert intoQualified-Student values( ‘s9’, ‘Lisa’, 4.0 ) insert intoQualified-Student values( ‘s10’, ‘Peter’, 1.7 ) Why are some views not updateable? What type of views are updateable?