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Database Design: Normalization and The Relational Model University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management IS 257 – Fall 2004 2004.09.22 - SLIDE 1 Lecture Outline • Review – Logical Design for the Diveshop database • Normalization IS 257 – Fall 2004 2004.09.22 - SLIDE 2 Lecture Outline • Review – Logical Design for the Diveshop database • Normalization IS 257 – Fall 2004 2004.09.22 - SLIDE 3 Database Design Process Application 1 External Model Application 2 Application 3 Application 4 External Model External Model External Model Application 1 Conceptual requirements Application 2 Conceptual requirements Application 3 Conceptual requirements Conceptual Model Logical Model Internal Model Application 4 Conceptual requirements IS 257 – Fall 2004 2004.09.22 - SLIDE 4 DiveShop ER Diagram Customer No DiveCust 1 Destination Name Destination no Customer No ShipVia n Dest n 1 DiveOrds n 1 ShipVia ShipVia 1 Destination no Site No 1 n Site No BioSite Species No 1 Destination n Sites Order No n 1 1/n ShipWrck Order No DiveItem n Item No n Site No 1 Species No BioLife IS 257 – Fall 2004 1 DiveStok Item No 2004.09.22 - SLIDE 5 Logical Design: Mapping to a Relational Model • Each entity in the ER Diagram becomes a relation. • A properly normalized ER diagram will indicate where intersection relations for many-to-many mappings are needed. • Relationships are indicated by common columns (or domains) in tables that are related. • We will examine the tables for the Diveshop derived from the ER diagram IS 257 – Fall 2004 2004.09.22 - SLIDE 6 Customer = DIVECUST Customer No Name Street City State/Prov Zip/Postal Code Country 1480 Louis Jazdzewski 2501 O'Connor New Orleans LA 60332 U.S.A. 1481 Barbara Wright 6344 W. Freeway San Francisco CA 95031 U.S.A. 1909 Stephen Bredenburg 559 N.E. 167 Indianapolis Place IN 46241 U.S.A. 1913 Phillip Davoust 123 First Street Berkeley CA 94704 U.S.A. 1969 David Burgett 320 Montgomery SeattleStreet WA 98105 U.S.A. 2001 Mary Rioux1701 Gateway Pueblo Blvd. #385 CO 81002 U.S.A. 2306 Kim Lopez 14134 Nottingham HonoluluLane HI 96826 U.S.A. 2589 Hiram Marley 7233 Mill Run SanDrive Francisco CA 94123 U.S.A. 3154 Tanya Kulesa 505 S. Flower, NewMail YorkStop NY 48943 10032 U.S.A. 3333 Charles Sekaron 110 East Park Miller Avenue,SD Box 8 57362 U.S.A. 3684 Lowell Lutz915 E. Fesler Dallas TX 75043 U.S.A. 4158 Keith Lucas56 South Euclid Chicago IL 60542 U.S.A. 4175 Karen Ng 2134 ElmhillKlamath Pike Falls OR 97603 U.S.A. 5510 Ken Soule 58 Sansome Aurora Street CO 89022 U.S.A. IS 257 – Fall 2004 Phone First Contact (902) 555-88881/29/95 (415) 555-43212/2/93 (317) 555-36441/5/93 (415) 555-91843/9/98 (206) 555-75803/12/99 (719) 555-20103/15/97 (808) 555-50501/29/99 (415) 555-64302/18/99 (212) 555-67501/30/99 (613) 555-43333/16/98 (214) 555-27222/15/99 (312) 555-43103/17/98 (503) 555-47003/20/99 (303) 555-66952/5/99 2004.09.22 - SLIDE 7 Mapping to Other Models • Hierarchical – Need to make decisions about access paths • Network – Need to pre-specify all of the links and sets • Object-Oriented – What are the objects, datatypes, their methods and the access points for them • Object-Relational – Same as relational, but what new datatypes might be needed or useful (more on OR later) IS 257 – Fall 2004 2004.09.22 - SLIDE 8 Lecture Outline • Review – Logical Design for the Diveshop database • Normalization IS 257 – Fall 2004 2004.09.22 - SLIDE 9 Normalization • Normalization theory is based on the observation that relations with certain properties are more effective in inserting, updating and deleting data than other sets of relations containing the same data • Normalization is a multi-step process beginning with an “unnormalized” relation – Hospital example from Atre, S. Data Base: Structured Techniques for Design, Performance, and Management. IS 257 – Fall 2004 2004.09.22 - SLIDE 10 Normal Forms • • • • • • First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Boyce-Codd Normal Form (BCNF) Fourth Normal Form (4NF) Fifth Normal Form (5NF) IS 257 – Fall 2004 2004.09.22 - SLIDE 11 Normalization No transitive dependency between nonkey attributes All determinants are candidate keys - Single multivalued dependency IS 257 – Fall 2004 BoyceCodd and Higher Functional dependency of nonkey attributes on the primary key - Atomic values only Full Functional dependency of nonkey attributes on the primary key 2004.09.22 - SLIDE 12 Unnormalized Relations • First step in normalization is to convert the data into a two-dimensional table • In unnormalized relations data can repeat within a column IS 257 – Fall 2004 2004.09.22 - SLIDE 13 Unnormalized Relation Patient # Surgeon # 145 1111 311 Surg. date Patient Name Jan 1, 1995; June 12, 1995 John White Patient Addr Surgeon 15 New St. New York, NY 243 1234 467 2345 189 Jan 8, 1996 Charles Brown 4876 145 Nov 5, 1995 Hal Kane 5123 145 May 10, 1995 Paul Kosher Charles Field 10 Main St. Patricia Rye, NY Gold Dogwood Lane Harrison, David NY Rosen 55 Boston Post Road, Chester, CN Beth Little Blind Brook Mamaronec k, NY Beth Little 6845 243 Apr 5, 1994 Dec 15, 1984 Ann Hood Hilton Road Larchmont, Charles NY Field IS 257 – Fall 2004 Postop drug Drug side effects Gallstone s removal; Beth Little Kidney Michael stones Penicillin, Diamond removal none- Apr 5, 1994 May 10, 1995 Mary Jones Surgery rash none Eye Cataract removal Thrombos Tetracyclin Fever is removal e none none Open Heart Surgery Cholecyst ectomy Gallstone s Removal Eye Cornea Replacem ent Eye cataract removal Cephalosp orin none Demicillin none none none Tetracyclin e Fever 2004.09.22 - SLIDE 14 First Normal Form • To move to First Normal Form a relation must contain only atomic values at each row and column. – No repeating groups – A column or set of columns is called a Candidate Key when its values can uniquely identify the row in the relation. IS 257 – Fall 2004 2004.09.22 - SLIDE 15 First Normal Form Patient # Surgeon # Surgery DatePatient Name Patient Addr Surgeon Name 1111 145 01-Jan-95 John White 1111 311 12-Jun-95 John White 15 New St. New York, NY 15 New St. New York, NY 1234 243 05-Apr-94 Mary Jones 10 Main St. Rye, NY 1234 467 10-May-95 Mary Jones 2345 4876 5123 6845 6845 IS 257 – Fall 2004 189 145 145 243 243 Charles 08-Jan-96 Brown 10 Main St. Rye, NY Dogwood Lane Harrison, NY 05-Nov-95 Hal Kane 55 Boston Post Road, Chester, CN 05-Apr-94 Ann Hood 15-Dec-84 Ann Hood Hilton Road Larchmont, NY Drug adminSide Effects Charles Field Gallstone s removal Kidney stones removal Eye Cataract removal Patricia Gold Thrombos is removal none none David Rosen Open Heart Surgery none Beth Little Cholecyst ectomy Demicillin Beth Little Michael Diamond Blind Brook Mamaronec 10-May-95 Paul Kosher k, NY Beth Little Hilton Road Larchmont, NY Surgery Penicillin rash none none Tetracyclin e Fever Cephalosp orin Charles Field Gallstone s Removal none Eye Cornea Replacem Tetracyclin ent e Charles Field Eye cataract removal none none none Fever none 2004.09.22 - SLIDE 16 1NF Storage Anomalies • Insertion: A new patient has not yet undergone surgery -- hence no surgeon # -- Since surgeon # is part of the key we can’t insert. • Insertion: If a surgeon is newly hired and hasn’t operated yet -- there will be no way to include that person in the database. • Update: If a patient comes in for a new procedure, and has moved, we need to change multiple address entries. • Deletion (type 1): Deleting a patient record may also delete all info about a surgeon. • Deletion (type 2): When there are functional dependencies (like side effects and drug) changing one item eliminates other information. IS 257 – Fall 2004 2004.09.22 - SLIDE 17 Second Normal Form • A relation is said to be in Second Normal Form when every nonkey attribute is fully functionally dependent on the primary key. – That is, every nonkey attribute needs the full primary key for unique identification IS 257 – Fall 2004 2004.09.22 - SLIDE 18 Second Normal Form Patient # 1111 1234 2345 4876 5123 6845 IS 257 – Fall 2004 Patient Name Patient Address 15 New St. New John White York, NY 10 Main St. Rye, Mary Jones NY Charles Dogwood Lane Brown Harrison, NY 55 Boston Post Hal Kane Road, Chester, Blind Brook Paul Kosher Mamaroneck, NY Hilton Road Ann Hood Larchmont, NY 2004.09.22 - SLIDE 19 Second Normal Form Surgeon # Surgeon Name 145 Beth Little 189 David Rosen 243 Charles Field 311 Michael Diamond 467 Patricia Gold IS 257 – Fall 2004 2004.09.22 - SLIDE 20 Second Normal Form Patient # Surgeon # Surgery Date 1111 1111 1234 1234 2345 4876 Drug Admin Side Effects 145 Gallstones 01-Jan-95 removal Kidney Penicillin rash 311 stones 12-Jun-95 removal none none 243 Eye Cataract 05-Apr-94 removal Tetracycline Fever 467 Thrombosis 10-May-95 removal 189 Open Heart 08-Jan-96 Surgery Cephalospori n none 145 Cholecystect 05-Nov-95 omy Demicillin none none none none none 5123 145 6845 243 6845 243 IS 257 – Fall 2004 Surgery Gallstones 10-May-95 Removal Eye cataract 15-Dec-84 removal Eye Cornea 05-Apr-94 Replacement none none Tetracycline Fever 2004.09.22 - SLIDE 21 1NF Storage Anomalies Removed • Insertion: Can now enter new patients without surgery. • Insertion: Can now enter Surgeons who haven’t operated. • Deletion (type 1): If Charles Brown dies the corresponding tuples from Patient and Surgery tables can be deleted without losing information on David Rosen. • Update: If John White comes in for third time, and has moved, we only need to change the Patient table IS 257 – Fall 2004 2004.09.22 - SLIDE 22 2NF Storage Anomalies • Insertion: Cannot enter the fact that a particular drug has a particular side effect unless it is given to a patient. • Deletion: If John White receives some other drug because of the penicillin rash, and a new drug and side effect are entered, we lose the information that penicillin can cause a rash • Update: If drug side effects change (a new formula) we have to update multiple occurrences of side effects. IS 257 – Fall 2004 2004.09.22 - SLIDE 23 Third Normal Form • A relation is said to be in Third Normal Form if there is no transitive functional dependency between nonkey attributes – When one nonkey attribute can be determined with one or more nonkey attributes there is said to be a transitive functional dependency. • The side effect column in the Surgery table is determined by the drug administered – Side effect is transitively functionally dependent on drug so Surgery is not 3NF IS 257 – Fall 2004 2004.09.22 - SLIDE 24 Third Normal Form Patient # Surgeon # Surgery Date IS 257 – Fall 2004 Surgery Drug Admin 1111 145 1111 311 01-Jan-95 Gallstones removal Kidney stones 12-Jun-95 removal Penicillin 1234 243 05-Apr-94 Eye Cataract removal Tetracycline 1234 467 10-May-95 Thrombosis removal 2345 189 08-Jan-96 Open Heart Surgery Cephalosporin 4876 145 05-Nov-95 Cholecystectomy Demicillin 5123 145 10-May-95 Gallstones Removal none 6845 243 none 6845 243 15-Dec-84 Eye cataract removal Eye Cornea 05-Apr-94 Replacement none none Tetracycline 2004.09.22 - SLIDE 25 Third Normal Form Drug Admin IS 257 – Fall 2004 Side Effects Cephalosporin none Demicillin none none none Penicillin rash Tetracycline Fever 2004.09.22 - SLIDE 26 2NF Storage Anomalies Removed • Insertion: We can now enter the fact that a particular drug has a particular side effect in the Drug relation. • Deletion: If John White recieves some other drug as a result of the rash from penicillin, but the information on penicillin and rash is maintained. • Update: The side effects for each drug appear only once. IS 257 – Fall 2004 2004.09.22 - SLIDE 27 Boyce-Codd Normal Form • Most 3NF relations are also BCNF relations. • A 3NF relation is NOT in BCNF if: – Candidate keys in the relation are composite keys (they are not single attributes) – There is more than one candidate key in the relation, and – The keys are not disjoint, that is, some attributes in the keys are common IS 257 – Fall 2004 2004.09.22 - SLIDE 28 Most 3NF Relations are also BCNF – Is this one? Patient # Patient Name Patient Address 15 New St. New 1111 John White York, NY 10 Main St. Rye, 1234 Mary Jones NY Charles Dogwood Lane 2345 Brown Harrison, NY 55 Boston Post 4876 Hal Kane Road, Chester, Blind Brook 5123 Paul Kosher Mamaroneck, NY Hilton Road 6845 Ann Hood Larchmont, NY IS 257 – Fall 2004 2004.09.22 - SLIDE 29 BCNF Relations Patient # Patient Name IS 257 – Fall 2004 Patient # 1111 John White 1111 1234 Mary Jones Charles 2345 Brown 1234 4876 Hal Kane 4876 5123 Paul Kosher 5123 6845 Ann Hood 6845 2345 Patient Address 15 New St. New York, NY 10 Main St. Rye, NY Dogwood Lane Harrison, NY 55 Boston Post Road, Chester, Blind Brook Mamaroneck, NY Hilton Road Larchmont, NY 2004.09.22 - SLIDE 30 Fourth Normal Form • Any relation is in Fourth Normal Form if it is BCNF and any multivalued dependencies are trivial • Eliminate non-trivial multivalued dependencies by projecting into simpler tables IS 257 – Fall 2004 2004.09.22 - SLIDE 31 Fifth Normal Form • A relation is in 5NF if every join dependency in the relation is implied by the keys of the relation • Implies that relations that have been decomposed in previous NF can be recombined via natural joins to recreate the original relation. IS 257 – Fall 2004 2004.09.22 - SLIDE 32 Effectiveness and Efficiency Issues for DBMS • Focus on the relational model • Any column in a relational database can be searched for values. • To improve efficiency indexes using storage structures such as BTrees and Hashing are used • But many useful functions are not indexable and require complete scans of the the database IS 257 – Fall 2004 2004.09.22 - SLIDE 33 Example: Text Fields • In conventional RDBMS, when a text field is indexed, only exact matching of the text field contents (or Greater-than and Lessthan). – Can search for individual words using pattern matching, but a full scan is required. • Text searching is still done best (and fastest) by specialized text search programs (Search Engines) that we will look at more later. IS 257 – Fall 2004 2004.09.22 - SLIDE 34 Normalization • Normalization is performed to reduce or eliminate Insertion, Deletion or Update anomalies. • However, a completely normalized database may not be the most efficient or effective implementation. • “Denormalization” is sometimes used to improve efficiency. IS 257 – Fall 2004 2004.09.22 - SLIDE 35 Normalizing to death • Normalization splits database information across multiple tables. • To retrieve complete information from a normalized database, the JOIN operation must be used. • JOIN tends to be expensive in terms of processing time, and very large joins are very expensive. IS 257 – Fall 2004 2004.09.22 - SLIDE 36 Downward Denormalization Customer ID Address Name Telephone Before: Order Order No Date Taken Date Dispatched Date Invoiced Cust ID IS 257 – Fall 2004 After: Customer ID Address Name Telephone Order Order No Date Taken Date Dispatched Date Invoiced Cust ID Cust Name 2004.09.22 - SLIDE 37 Upward Denormalization Order Order No Date Taken Date Dispatched Date Invoiced Cust ID Cust Name Order Item Order No Item No Item Price Num Ordered IS 257 – Fall 2004 Order Order No Date Taken Date Dispatched Date Invoiced Cust ID Cust Name Order Price Order Item Order No Item No Item Price Num Ordered 2004.09.22 - SLIDE 38 Denormalization • Usually driven by the need to improve query speed • Query speed is improved at the expense of more complex or problematic DML (Data manipulation language) for updates, deletions and insertions. IS 257 – Fall 2004 2004.09.22 - SLIDE 39 Using RDBMS to help normalize • Example database: Cookie • Database of books, libraries, publisher and holding information for a shared (union) catalog IS 257 – Fall 2004 2004.09.22 - SLIDE 40 Cookie relationships IS 257 – Fall 2004 2004.09.22 - SLIDE 41 Cookie BIBFILE relation ACCNO A003 T082 C024 B006 B007 B005 B008 B010 B009 B012 B011 B014 B013 B016 B017 F047 B116 S102 B118 B018 C031 C032 C034 AUTHOR TITLE LOC PUBID DATE PRICE AMERICAN LIBRARY ASSOCIATION ALA BULLETIN CHICAGO 04 $3.00 ANDERSON, THEODORE THE TEACHING OF MODERN PARIS LANGUAGES 53 1955 $10.95 AXT, RICHARD G. COLLEGE SELF STUDY BOULDER, : LECTURES CO. ON 51INSTITU 1960 $7.00 BALDERSTON, FREDERICK MANAGING E. TODAYS SAN UNIVERSITY FRANCISCO 27 1975 $6.00 BARZUN, JACQUES TEACHER IN AMERICA GARDEN CITY 18 1954 $7.00 BARZUN, JACQUES THE AMERICAN UNIVERSITY NEW YORK : HOW IT 24 RUNS, W 1970 $5.00 BARZUN, JACQUES THE HOUSE OF INTELLECT NEW YORK 24 1961 $8.00 BELL, DANIEL THE COMING OF POST-INDUSTRIAL NEW YORK SOCIETY 09 1976 : $10.00 BENSON, CHARLES S. IMPLEMENTING THE SAN LEARNING FRANCISCO SOCIETY 27 1974 $9.00 BERG, IVAR EDUCATION AND JOBS BOSTON : THE GREAT TRAINING 10 1971 $12.00 BERSI, ROBERT M. RESTRUCTURING THE WASHINGTON, BACCALAUREATE D.C. 03 1973 $11.00 BEVERIDGE, WILLIAM I.THE ART OF SCIENTIFIC NEWINVESTIGATION YORK 58 1957 $14.00 BIRD, CAROLINE THE CASE AGAINST NEW COLLEGE YORK 08 1975 $13.00 BISSELL, CLAUDE T. THE STRENGTH OF THE TORONTO UNIVERSITY 57 1968 $14.00 BLAIR, GLENN MYERS EDUCATIONAL PSYCHOLOGY NEW YORK 30 1962 $11.00 BLAKE, ELIAS, JR. THE FUTURE OF THECAMBRIDGE, BLACK COLLEGES MA.02 1971 $14.25 BOLAND, R.J. CRITICAL ISSUES IN INFORMATION CHICHESTER, ENG. SYSTEMS 63 1987 R $30.95 BROWN, SANBORN C., SCIENTIFIC ED. MANPOWER CAMBRIDGE, MASS. 29 1971 $4.00 BUCKLAND, MICHAEL K.LIBRARY SERVICES ELMSFORD, IN THEORY AND NY CONTEXT 70 1983 $12.00 BUDIG, GENE A. ACADEMIC QUICKSAND LINCOLN, : SOME NEBRASKA TRENDS 37 AND1973 ISS $13.00 CALIFORNIA. DEPT. OFLAW JUSTICE IN THE SCHOOLMONTCLAIR, N.J. 35 1974 $0.50 CAMPBELL, MARGARET WHY A. WOULD A GIRLOLD GO INTO WESTBURY, MEDICINE? 48 N.Y. 1973 $1.50 CARNEGIE COMMISSION A DIGEST ON HIGHER OF REPORTS NEW OF YORK THE CARNEGIE 30 COMM 1974 $3.50 IS 257 – Fall 2004 PAGINATION ILL HEIGHT 63 V. ILL. 26 294 P. 22 X, 300 P. GRAPHS 28 XVI, 307 P. 24 280 P. 18 XII, 319 P. 20 VIII, 271 P. 21 XXVII, 507 P. 21 XVII, 147 P. 24 XX, 200 P. 21 IV, 160P. 23 XIV, 239 P. 18 XII, 308 P. 18 VII, 251 P. 21 678 P. 24 VIII, PP. 539 23 XV, 394 P. ILL. 24 X, 180 P. 26 XII, 201 P. ILL. 23 74 P. 23 IV, 87 P. 21 V, 114 P. 24 399 P. 24 2004.09.22 - SLIDE 42 How to Normalize? • Currently no way to have multiple authors for a given book, and there is duplicate data spread over the BIBFILE table • Can we use the DBMS to help us normalize? • Access example… IS 257 – Fall 2004 2004.09.22 - SLIDE 43 Next Week • Physical DB Design and Access Methods IS 257 – Fall 2004 2004.09.22 - SLIDE 44