12/5/2000Information Organization and Retrieval Database Design: Normalization and SQL University of...

12/5/2000 Information Organization and Retrieval

Database Design: Normalization and SQL

University of California, Berkeley

School of Information Management and Systems

SIMS 202: Information Organization and Retrieval


Review

• Database design Process

• Entity-Relationship Diagrams

• Designing a database


Database Design Process

ConceptualModel

LogicalModel

External Model

Conceptual requirements




Application 1

Application 1

Application 2 Application 3 Application 4

Application 2

Application 3

Application 4

External Model

External Model

External Model

Internal Model


ER Diagrams: Entity

• An Entity is an object in the real world (or even imaginary worlds) about which we want or need to maintain information– Persons (e.g.: customers in a business,

employees, authors)– Things (e.g.: purchase orders, meetings, parts,

companies)

Employee


ER Diagrams: Attributes

• Attributes are the significant properties or characteristics of an entity that help identify it and provide the information needed to interact with it or use it. (This is the Metadata for the entities.)

Employee

Last

Middle

First

Name SSN

Age

Birthdate

Projects


ER Diagrams: Relationships

ClassAttendsStudent

PartSuppliesproject

partsSupplier

Project


ACME Widget Co. Entities

• Customer• Invoice• Employee• Inventory• Supplier• Account• Sales Rep• Parts

• Timecard• Check


ACME Widget Co. Functional areas

• Ordering• Inventory• Supplies• Shipping• Personnel• Payroll• We will concentrate on Ordering and

Inventory


ACME WidgetOrdering Normalization

OrdersCustomer

Cust#

Invoice

Writes

Sales-Rep

Invoice#

Rep#

Rep#

Line-ItemContains

Part#

QuantityInvoice#

Cust#


ACME WidgetER Model

OrdersCustomer

Cust#

Invoice

Writes

Sales-Rep

Invoice#

Sales

Rep#

Line-ItemContains

Part#

QuantityInvoice#

Cust#Contains

Part

Part# Count

Price

Supplier

Company#

OrderedPart

Hourly

Employee

ISA

Emp#Wage

Company#

Part# Cost

SuppliedPart

Has

On-Order

Supplies

Company#

Part# Quantity


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 Acme Widget Company derived from the ER diagram


Employee

SSN Lastname Firstname Middlename Birthdate Address City123-76-3423 Jones Janet Mary 6/25/63 234 State Berkeley342-88-7865 Smith Thomas Frederick 8/4/70 12 Lambert Oakland486-87-6543 Hendersen Charles Robert 9/23/61 44 Central Berkeley843-36-7659 Martinez Roberto Garcia 7/8/58 76 Highland Berkeley… … … … … … …


Sales-RepSSN Rep # Sales123-76-3423 1 $12,345.45843-36-7659 2 $231,456.75

HourlySSN Wage342-88-7865 $12.75486-87-6543 $20.50


CustomerCust # COMPANY STREET1 STREET2 CITY STATE ZIPCODE

1Integrated Standards Ltd. 35 Broadway Floor 12 New York NY 02111

2 MegaInt Inc. 34 Bureaucracy Plaza Floors 1-172 Phildelphia PA 03756

3 Cyber Associates3 Control Elevation Place

Cyber Assicates Center Cyberoid NY 08645

4General Consolidated 35 Libra Plaza Nashua NH 09242

5Consolidated MultiCorp 1 Broadway Middletown IN 32467

6Internet Behometh Ltd. 88 Oligopoly Place Sagrado TX 78798

7Consolidated Brands, Inc.

3 Independence Parkway Rivendell CA 93456

8 Little Mighty Micro 34 Last One Drive Orinda CA 94563

9 SportLine Ltd. 38 Champion Place Suite 882 Compton CA 95328


Invoice

Invoice # Cust # Rep #93774 3 184747 4 188367 5 288647 9 1

776879 2 265689 6 2


Line-Item

Invoice # Part # Quantity93774 3 1084747 23 188367 75 288647 4 3

776879 22 565689 76 1293774 23 1088367 34 2


PartPart # Name Price Count

1 Big blue widget 3.76 22 Small blue Widget 7.35 43 Tiny red widget 5.25 74 large red widget 157.23 235 double widget rack 10.44 126 Small green Widget 30.45 587 Big yellow widget 7.96 18 Tiny orange widget 81.75 429 Big purple widget 55.99 9


JoinsPart # Name Price Count

1 Big blue widget 3.76 22 Small blue Widget 7.35 43 Tiny red widget 5.25 74 large red widget 157.23 235 double widget rack 10.44 126 Small green Widget 30.45 587 Big yellow widget 7.96 18 Tiny orange widget 81.75 429 Big purple widget 55.99 9

Invoice # Part # Quantity93774 3 1084747 23 188367 75 288647 4 3

776879 22 565689 76 1293774 23 1088367 34 2

Invoice # Cust # Rep #93774 3 184747 4 188367 5 288647 9 1

776879 2 265689 6 2

Cust # COMPANY STREET1 STREET2 CITY STATE ZIPCODE

1Integrated Standards Ltd. 35 Broadway Floor 12 New York NY 02111

2 MegaInt Inc. 34 Bureaucracy Plaza Floors 1-172 Phildelphia PA 03756

3 Cyber Associates3 Control Elevation Place

Cyber Assicates Center Cyberoid NY 08645

4General Consolidated 35 Libra Plaza Nashua NH 09242

5Consolidated MultiCorp 1 Broadway Middletown IN 32467

6Internet Behometh Ltd. 88 Oligopoly Place Sagrado TX 78798

7Consolidated Brands, Inc.

3 Independence Parkway Rivendell CA 93456

8 Little Mighty Micro 34 Last One Drive Orinda CA 94563

9 SportLine Ltd. 38 Champion Place Suite 882 Compton CA 95328


Today

• Normalization

• Relational Algebra and Calculus

• SQL

• Effectiveness and Efficiency criteria for database designs

• Advantages and failings of DBMS technology


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.


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)


Normalization

Boyce-Codd and

Higher

Functional dependencyof nonkey attributes on the primary key - Atomic values only

Full Functional dependencyof nonkey attributes on the primary key

No transitive dependency between nonkey attributes

All determinants are candidate keys - Single multivalued dependency


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


Unnormalized RelationPatient # Surgeon # Surg. date Patient Name Patient Addr Surgeon Surgery Postop drugDrug side effects

1111145 311

Jan 1, 1995; June 12, 1995 John White

15 New St. New York, NY

Beth Little Michael Diamond

Gallstones removal; Kidney stones removal

Penicillin, none-

rash none

1234243 467

Apr 5, 1994 May 10, 1995 Mary Jones

10 Main St. Rye, NY

Charles Field Patricia Gold

Eye Cataract removal Thrombosis removal

Tetracycline none

Fever none

2345 189Jan 8, 1996 Charles Brown

Dogwood Lane Harrison, NY

David Rosen

Open Heart Surgery

Cephalosporin none

4876 145Nov 5, 1995 Hal Kane

55 Boston Post Road, Chester, CN Beth Little

Cholecystectomy Demicillin none

5123 145May 10, 1995 Paul Kosher

Blind Brook Mamaroneck, NY Beth Little

Gallstones Removal none none

6845 243

Apr 5, 1994 Dec 15, 1984 Ann Hood

Hilton Road Larchmont, NY

Charles Field

Eye Cornea Replacement Eye cataract removal

Tetracycline Fever


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.


First Normal FormPatient # Surgeon #Surgery DatePatient NamePatient AddrSurgeon Name Surgery Drug adminSide Effects

1111 145 01-Jan-95 John White

15 New St. New York, NY Beth Little

Gallstones removal Penicillin rash

1111 311 12-Jun-95 John White

15 New St. New York, NY

Michael Diamond

Kidney stones removal none none

1234 243 05-Apr-94 Mary Jones10 Main St. Rye, NY Charles Field

Eye Cataract removal

Tetracycline Fever

1234 467 10-May-95 Mary Jones10 Main St. Rye, NY Patricia Gold

Thrombosis removal none none

2345 189 08-Jan-96Charles Brown

Dogwood Lane Harrison, NY David Rosen

Open Heart Surgery

Cephalosporin none

4876 145 05-Nov-95 Hal Kane

55 Boston Post Road, Chester, CN Beth Little

Cholecystectomy Demicillin none

5123 145 10-May-95 Paul Kosher

Blind Brook Mamaroneck, NY Beth Little

Gallstones Removal none none

6845 243 05-Apr-94 Ann Hood

Hilton Road Larchmont, NY Charles Field

Eye Cornea Replacement

Tetracycline Fever

6845 243 15-Dec-84 Ann Hood

Hilton Road Larchmont, NY Charles Field

Eye cataract removal none none


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.


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


Second Normal FormPatient # Patient Name Patient Address

1111 John White15 New St. New York, NY

1234 Mary Jones10 Main St. Rye, NY

2345Charles Brown


4876 Hal Kane55 Boston Post Road, Chester,

5123 Paul KosherBlind Brook Mamaroneck, NY

6845 Ann HoodHilton Road Larchmont, NY


Second Normal FormSurgeon # Surgeon Name

145 Beth Little

189 David Rosen

243 Charles Field

311 Michael Diamond

467 Patricia Gold


Second Normal FormPatient # Surgeon # Surgery Date Surgery Drug Admin Side Effects

1111 145 01-Jan-95Gallstones removal Penicillin rash

1111 311 12-Jun-95

Kidney stones removal none none

1234 243 05-Apr-94Eye Cataract removal Tetracycline Fever

1234 467 10-May-95Thrombosis removal none none

2345 189 08-Jan-96Open Heart Surgery

Cephalosporin none

4876 145 05-Nov-95Cholecystectomy Demicillin none

5123 145 10-May-95Gallstones Removal none none

6845 243 15-Dec-84Eye cataract removal none none

6845 243 05-Apr-94Eye Cornea Replacement Tetracycline Fever


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


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.


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


Third Normal FormPatient # Surgeon # Surgery Date Surgery Drug Admin

1111 145 01-Jan-95 Gallstones removal Penicillin

1111 311 12-Jun-95Kidney stones removal none

1234 243 05-Apr-94 Eye Cataract removal Tetracycline

1234 467 10-May-95 Thrombosis removal none

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 15-Dec-84 Eye cataract removal none

6845 243 05-Apr-94Eye Cornea Replacement Tetracycline


Third Normal Form

Drug Admin Side Effects

Cephalosporin none

Demicillin none

none none

Penicillin rash

Tetracycline Fever


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.


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


Most 3NF Relations are also BCNF

Patient # Patient Name Patient Address

1111 John White15 New St. New York, NY

1234 Mary Jones10 Main St. Rye, NY

2345Charles Brown


4876 Hal Kane55 Boston Post Road, Chester,

5123 Paul KosherBlind Brook Mamaroneck, NY

6845 Ann HoodHilton Road Larchmont, NY


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


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.


Relational Calculus

• Relational Algebra provides a set of explicit operations (select, project, join, etc) that can be used to build some desired relation from the database.

• Relational Calculus provides a notation for formulating the definition of that desired relation in terms of the relations in the database without explicitly stating the operations to be performed

• SQL is based on the relational calculus.


Relational Algebra Operations

• Select• Project• Product• Union• Intersect• Difference• Join• Divide


Select

• Extracts specified tuples (rows) from a specified relation (table).


Project

• Extracts specified attributes(columns) from a specified relation.


Join

• Builds a relation from two specified relations consisting of all possible concatenated pairs of, one from each of the two relations, such that in each pair the two tuples satisfy some condition.

A1 B1A2 B1A3 B2

B1 C1B2 C2B3 C3

A1 B1 C1A2 B1 C1A3 B2 C2

(Naturalor Inner)

Join


Outer Join

• Outer Joins are similar to PRODUCT -- but will leave NULLs for any row in the first table with no corresponding rows in the second.

A1 B1A2 B1A3 B2A4 B7

B1 C1B2 C2B3 C3

A1 B1 C1A2 B1 C1A3 B2 C2A4 * *

Outer Join


SQL

• Structured Query Language

• SEQUEL from IBM San Jose

• ANSI 1992 Standard is the version used by most DBMS today (SQL92)

• Basic language is standardized across relational DBMSs. Each system may have proprietary extensions to standard.


SQL Uses

• Database Definition and Querying– Can be used as an interactive query language– Can be imbedded in programs

• Relational Calculus combines Select, Project and Join operations in a single command. SELECT.


SELECT

• Syntax:– SELECT [DISTINCT] attr1, attr2,…, attr3

FROM rel1 r1, rel2 r2,… rel3 r3 WHERE condition1 {AND | OR} condition2 ORDER BY attr1 [DESC], attr3 [DESC]


SELECT Conditions• = equal to a particular value• >= greater than or equal to a particular value• > greater than a particular value• <= less than or equal to a particular value• <> not equal to a particular value• LIKE “*term*” (may be other wild cards in other

systems)• IN (“opt1”, “opt2”,…,”optn”)• BETWEEN val1 AND val2• IS NULL


Relational Algebra Selection using SELECT

• Syntax:– SELECT * WHERE condition1 {AND | OR}

condition2


Relational Algebra Projection using SELECT

• Syntax:– SELECT [DISTINCT] attr1, attr2,…, attr3

FROM rel1 r1, rel2 r2,… rel3 r3


Relational Algebra Join using SELECT

• Syntax:– SELECT * FROM rel1 r1, rel2 r2 WHERE

r1.linkattr = r2.linkattr


Sorting

• SELECT BIOLIFE.[Common Name], BIOLIFE.[Length (cm)]

FROM BIOLIFE

ORDER BY BIOLIFE.[Length (cm)] DESC;


Subqueries

• SELECT SITES.[Site Name], SITES.[Destination no]

FROM SITES WHERE sites.[Destination no] IN

(SELECT [Destination no] from DEST where [avg temp (f)] >= 78);

• Can be used as a form of JOIN.


Aggregate Functions

• Count• Avg• SUM• MAX• MIN


Using Aggregate functions

• SELECT attr1, Sum(attr2) AS name FROM tab1, tab2 ...

GROUP BY attr1, attr3 HAVING condition;


Using an Aggregate Function

• SELECT DIVECUST.Name, Sum([Price]*[qty]) AS Total

FROM (DIVECUST INNER JOIN DIVEORDS ON DIVECUST.[Customer No] = DIVEORDS.[Customer No]) INNER JOIN DIVEITEM ON DIVEORDS.[Order No] = DIVEITEM.[Order No]

GROUP BY DIVECUST.Name

HAVING (((DIVECUST.Name) Like "*Jazdzewski"));


GROUP BY• SELECT DEST.[Destination Name], Count(*) AS

Expr1 FROM DEST INNER JOIN DIVEORDS ON

DEST.[Destination Name] = DIVEORDS.Destination

GROUP BY DEST.[Destination Name] HAVING ((Count(*))>1);• Provides a list of Destinations with the number of

orders going to that destination


Create Table

• CREATE TABLE table-name (attr1 attr-type PRIMARYKEY, attr2 attr-type,…,attrN attr-type);

• Adds a new table with the specified attributes (and types) to the database.


Access Data Types

• Numeric (1, 2, 4, 8 bytes, fixed or float)• Text (255 max)• Memo (64000 max)• Date/Time (8 bytes)• Currency (8 bytes, 15 digits + 4 digits decimal)• Autonumber (4 bytes)• Yes/No (1 bit)• OLE (limited only by disk space)• Hyperlinks (up to 64000 chars)


Access Numeric types• Byte

– Stores numbers from 0 to 255 (no fractions). 1 byte

• Integer– Stores numbers from –32,768 to 32,767 (no fractions) 2 bytes

• Long Integer (Default) – Stores numbers from –2,147,483,648 to 2,147,483,647 (no fractions). 4

bytes

• Single– Stores numbers from -3.402823E38 to –1.401298E–45 for negative values

and from 1.401298E–45 to 3.402823E38 for positive values.4 bytes

• Double– Stores numbers from –1.79769313486231E308 to –4.94065645841247E–

324 for negative values and from 1.79769313486231E308 to 4.94065645841247E–324 for positive values. 15 8 bytes

• Replication ID– Globally unique identifier (GUID) N/A 16 bytes


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


Example: Text Fields

• In conventional RDBMS, when a text field is indexed, only exact matching of the text field contents (or Greater-than and Less-than). – 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.


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.


Advantages of RDBMS

• Possible to design complex data storage and retrieval systems with ease (and without conventional programming).

• Support for ACID transactions– Atomic – Consistent– Independent– Durable


Advantages of RDBMS

• Support for very large databases

• Automatic optimization of searching (when possible)

• RDBMS have a simple view of the database that conforms to much of the data used in businesses.

• Standard query language (SQL)


Disadvantages of RDBMS

• Until recently, no support for complex objects such as documents, video, images, spatial or time-series data. (ORDBMS are adding support these).

• Often poor support for storage of complex objects. (Disassembling the car to park it in the garage)

• Still no efficient and effective integrated support for things like text searching within fields.

12/5/2000Information Organization and Retrieval Database Design: Normalization and SQL University of...

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