begin [atomic] operation, operation, { commit rollback} end

Transcription

1 Set Processing Languages standard, simple data structure RELATION abstracted retrievals RELATIONAL ALGEBRA abstracted updating INSERT, DELETE, UPDATE transaction indivisible set of active operations begin [atomic] operation, operation, { commit rollback} end ENTITY INTEGRITY REFERENTIAL INTEGRITY BCNF Stefan Stanczyk

2 physical entities abstract entities St-No NAME HomeADDRESS TermADDRESS SEX DOB STUDENT DEPARTMENT DEPT# NAME HEAD-Id Staff-Id NAME ADDRESS QUAL SALARY DOB LECTURER MODULE MOD# TITLE LECTURER CREDIT TERM BUILDING OFFICE# AREA OFFICE PROJECT St-No TITLE SUPERVISOR GRADE YEAR association entity RESULTS St-No MOD# DATE GRADE Stefan Stanczyk

3 COMPILER John John DATABASE Eve Smith Eve EXPERT SYSTEM WORDPROCESSOR SPREADSHEET Mary Steve Brown Green Mary Steve www-browser Ann Ann PROJECT is-carried -out-by STUDENT LECTURER counsels STUDENT optional compulsory optional compulsory Stefan Stanczyk

4 Introduction to Calculus Mathematical Logic John Set Theory & Topology Eve Data Structures Mary Theory of Computation Steve Programming Information Systems STUDENT MODULE Peter Software Engineering Database Design Artificial Intelligence RESULTS STUDENT enrols MODULE compulsory optional Stefan Stanczyk

5 UNIVERSITY MEMBER carries out STUDENT COMPUTER SYSTEM PROJECT DEPARTMENT delivers has_account_on LECTURER supervises employs MODULE prerequisite_for OFFICE occupied by LECTURER is_on has supervises counsels TEACHING SCHEME PROJECT carried out_by STUDENT enjoys RESULTS Stefan Stanczyk

6 MARRIAGE M x W = {<PETER, ANNE>, <PAUL, JANE>, <STEVE, MARY>, < KEITH, SUE>} RELATION ::= subset of cartesian product where for every pair (x, y) a pre-defined proposition p(x, y) holds true attribute name relation name MARRIAGE HUSBAND PETER PAUL STEVE KEITH WIFE ANNE JANE MARY SUE attribute value tuple Stefan Stanczyk

7 PERSON-NAMES BIRTH-DATES CITIES Smith Jones London Brown Green Wilkes Tyler Paris New York Tokyo A relation R is a subset of an expanded cartesian product of n, not necessarily distinct domains D 1 x D 2 x..., x D n, such that : attribute (role) name for every element d k = <d k 1, dk 2,..., dk n > R a predefined p(<d k 1, dk 2,..., dk n >) is true; PERSON40 NAME DOB CITY relation name Smith London Jones New York Brown Paris tuple (row) d k i D i for every i=1, 2,...,n where k is a number of n-tuples in the relation R (cardinality of R) n is a number of attributes in the relation R (degree of R). column attribute value Stefan Stanczyk

8 R - a relation defined by p(d k ) on n domains D 1 x..., D n, so d k = <d k 1, dk 2,..., dk n > R; R - a relation defined by p'(δ l ) on m domains D j x..., D p, so δ l = <d l j,..., dl p > R' ; where d k i D i for i { 1, 2,...,n}, d l r Dr for r {1, 2,...,m} and n > m. domains SUPER-KEY R R' δis said to be a superkey for R if and only if δ p(d k ) and p'(δ l ) are referentially equivalent, i.e. whenever p(d k ) and p'(δ l ) are both true, both d k and δ l refer to the same Real World entity occurrence, in which case k = l and δ d is a bijection. If m is minimal then δ is a proper candidate key for R. Stefan Stanczyk

9 First Normal Form STUDENT-RECORD RECORD IDNAME SUBJECT GRADE ST-REC IDNAME SUBJECT GRADE S011 JOHN Mathematics B Programming A Databases B Data Structures C S173 MARY Electronics A Prolog B Mathematics A S112 PETER Programming C Prolog A S011 JOHN Mathematics B S011 JOHN Programming A S011 JOHN Databases B S011 JOHN Data Structures C S173 MARY Electronics A S173 MARY Prolog B S173 MARY Mathematics A S112 PETER Programming C S112 PETER Prolog A MODULES-TAKEN ID MODULES M1 M2 M3 S011 Mathematics Programming Databases Data Structures S173 Electronics Prolog Mathematics S112 Programming Prolog nil M-TAKEN IDMODULE S011 Mathematics S011 Programming S011 Databases S011 Data Structures S173 Electronics S173 Prolog S173 Mathematics S112 Programming S112 Prolog Stefan Stanczyk

10 Entity Integrity No prime attribute of a relation may hold a null value. DIRECTORY FNAME SNAME ADDRESS TELEPHONE John Adams 1 High Str Mary Adams 11 North Av x Adams 9 South Av Peter x 5 Dore Clo x x 13 Back Str not allowed Stefan Stanczyk

11 Referential Integrity foreign key COURSE.MODULE FOREIGN KEY Let R be a relation (, X) with a primary key, and S be a relation (A, Γ) where and Γ are defined on the same not necessarily simple domain. Then, Γ is said to be a foreign key in S. REFERENTIAL INTEGRITY REGISTER S-ID SUBJECT GRADE S011 Mathematics B S011 Programming A S011 Databases B S011 Data Structures C S011 Psychology A S173 Electronics A S173 Prolog B S173 Mathematics A S112 Programming C S112 Prolog A not allowed If a relation S includes a foreign key Γ matching the primary key of some other relation R then every value of Γ in S must be equal to the value of in some tuple of R or be wholly null. MODULE Mathematics Programming Data Structures Databases Electronics Prolog COURSE LECTURER-ID p123 p234 p345 p345 p123 p567 Stefan Stanczyk

12 OFFICE occupied_by LECTURER NUMBER BUILDING ID NAME DOB ADDRESS Main Block S027 Smith 21/3/56 London.. C31 Science S128 Jones 4/6/50 Oxford.. C43 Science S229 Brown 30/12/73 Abington.. L01 Laboratory S341 Green 1/3/71 Oxford.. IDNAME DOB A DRESS.. NUMBER BUILDING S027 Smith 21/3/56 London Main Block S128 Jones 4/6/50 Oxford.. C31 Science S229 Brown 30/12/73 Abington.. C43 Science S341 Green 1/3/71 Oxford.. L01 Laboratory N101 New Block X S678 Green 10/4/75 Oxford OK NUMBER BUILDING ID NAME DOB ADDRESS Main Block S027 Smith 21/3/56 London.. C31 Science S128 Jones 4/6/50 Oxford.. C43 Science S229 Brown 30/12/73 Abington.. L01 Laboratory S341 Green 1/3/71 Oxford.. N101 New Block S678 Green 10/4/75 Oxford.. OK X foreign key NUMBER BUILDING ID ID NAME DOB Main Block S027 S027 Smith 21/3/56.. C31 Science S128 S128 Jones 4/6/50.. C43 Science S229 S229 Brown 30/12/73.. L01 Laboratory S341 S341 Green 1/3/71.. N101 New Block S678 Green 10/4/75.. neither tuple exists Stefan Stanczyk

13 LECTURER counsels STUDENT IDNAME A DRESS.. STNO NAME SEX.. S027 Smith London.. S011 John M.. S128 Jones Oxford.. S173 Mary F.. S229 Brown Abington.. S145 Ann F.. S341 Green Oxford.. A132 Paul M.. S678 Green Oxford.. S112 Peter M.. S188 Neil M.. S196 Mary F.. STNO NAME SEX ID.. S011 John M S027.. S173 Mary F S027.. S145 Ann F S027.. A132 Paul M S229.. S112 Peter M S229.. S188 Neil M S229.. S196 Mary F S678.. foreign key Stefan Stanczyk

14 LECTURER decomposed MODULE TEACHING SCHEME IDNAME A DRESS.. CODE TITLE REQUIRES S027 Smith London Pascal 8001 S128 Jones Oxford Data Str 8021 S229 Brown Abington OO Prog 8011 S341 Green Oxford DB MM 8012 foreign key foreign key IDCODE.. S S S S S S S Stefan Stanczyk

15 prerequisite-for MODULE MODULE CODE PREQ CODE PREQ new record Stefan Stanczyk

16 UNIVERSITY MEMBER IDNAME DOB A DRESS super-entity STUDENT IDHALL ENROL-DATE exclusive or LECTURER IDQUALIFIC SALARY sub-entities Stefan Stanczyk

17 Referential Integrity Diagram STUDENT STNO NAME SEX DOB ADDRESS ENTRY REGISTER STNO CODE RESULT WHEN MODULE CODE TITLE REQUIRES TEACHID LECTURER IDNAME DOB A DRESS QUALIF POSITION OFFICE IDNUMBER BUILDING Stefan Stanczyk

18 Functional Dependency R X A B C x 1 a 1 b 1 c 1 x 2 a 2 b 2 c 2 x 3 a 3 b 3 c 3 x 4 a 4 b 4 c x n a n b n c n functional dependency A C holds for R iff the following is true: whenever a i = a k then c i = c k for all pairs (i, k) {1..n} A is called determinant Stefan Stanczyk

19 Boyce-Codd Normal Form A 1NF relation R(X1, X2,...Xn) is in BCNF if: for every attribute collection χ of R if any attribute not in χ is functionally dependent on χ then all attributes in R are functionally dependent on χ R is in BCNF X1 X2 X3 X4 X5 X6 X7 χ A relation is in BCNF if every determinant is a key Stefan Stanczyk

20 normalisation by non-loss decomposition OK PK X PK FK FK PK references Stefan Stanczyk

21 an example SEMINAR-RESULTS SIDWHO DATE TUTOR TOPIC MOD ROOM MARK BOOK SAL D29 John 20/5/97 Brown EAR 8049 G Bowen 20 D29 Mary 20/5/97 Brown EAR 8049 G Bowen 20 D17 John 28/2/97 Green FD 8049 A Navathe 68 M09 Anne 18/4/97 White Diff 8609 DG41 88 Kreitsky 55 D17 Mark 28/2/97 Green FD 8049 A Navathe 68 U21 Sue 20/5/97 Brown BCNF 8049 C Navathe 20 S31 John 22/3/97 Black EAR 8049 DT21 73 Bowen 41 P43 Sue 30/5/97 Jones Z 8043 C Hayes 29 candidate keys (WHO, SEMID) (WHO, DATE, TOPIC) (WHO, DATE, ROOM) (WHO, DATE, BOOK) Stefan Stanczyk

22 SIDWHO DATE TUTOR TOPIC MOD ROOM MARK BOOK SAL PK related to SEMINAR related to TUTOR related to TOPIC SIDWHO DATE TUTOR TOPIC MOD ROOM MARK BOOK SAL SIDWHO DATE TUTOR TOPIC ROOM MARK SAL TOPIC MOD BOOK SIDWHO DATE TUTOR TOPIC ROOM MARK TUTOR SAL SIDWHO MARK SIDDATE TUTOR TOPIC ROOM Stefan Stanczyk

23 TUTOR-DETAILS TUTOR SAL TEACHING-PROGRAMME TOPIC MOD BOOK SEMINAR-DETAILS SIDDATE TUTOR TOPIC ROOM SIDWHO RESULTS MARK TUTOR-DETAILS some tutors may not participate in seminars a seminar MUST be taught by somebody some seminars may not attract any students and thus have no associated results SEMINAR-DETAILS RESULTS and MUST be part of teaching programme no point of having a topic not taught all results MUST be associated with a seminar otherwise a mark would have been for a non-existing one TEACHING-PROGRAMME Stefan Stanczyk