Software Tools - Instructinstruct.uwo.ca/engin-sc/se352b/notes/HG-SE352Lect-W06... · 2006-03-04 · SE352b 3-Mar-06 (c) Hamada Ghenniwa, ECE, UWO 3 Feb 24, 2006 SE352b, ECE,UWO,

SE352b 3-Mar-06
(c) Hamada Ghenniwa, ECE, UWO 1
Feb 24, 2006 SE352b, ECE,UWO, Hamada Ghenniwa 1
SE352b Software Engineering SE352b Software Engineering Design ToolsDesign Tools
W6: W6: Database TechnologyDatabase Technology
Operational DatabaseOperational Database
Software ToolsSoftware Tools
Source Procedure A
Source Procedure B
Source Procedure C
Systems ProgrammingTools
Programming LanguageTools
DatabaseSystem

SE352b 3-Mar-06
DB Related IssuesDB Related Issues
Data Models
Schemas
Schema Architecture
DBMS Languages
DBMS Component Modules
Architecture of DBMS
Quality of Design in Relational DB
SQL in general context
Query Processing
Interacting with DBs
Classification of Classification of DBMSsDBMSs
Based on the data model used:
Traditional: Relational, Network, Hierarchical
Emerging: Object-oriented, Object-relational
Based on the number of users support
single-user (typically used with micro-computers)
multi-user (most DBMSs).

SE352b 3-Mar-06
Classification of Classification of DBMSsDBMSs(Cont(Cont.).)
Based on architecturecentralized
consists of a single DBMS managing a single DB
distributed consists of a single DBMS (calleddistributed DBMS, or DDBMS) that manages several DB that might be located at different computing systems
DBMS
DB
Centralized DBS
DDBMS
DB DB
Distributed DBS
Classification of Classification of DBMSsDBMSs(Cont(Cont.).)
A multi-database system (MDBS) supports operations on multiple DBSs,
each consists of separate DBMS or DDBMS
MDBMS
DB DB
DBMS DDBMS
Multi-DBS
DB

SE352b 3-Mar-06
33--Level SchemaLevel Schema
Internal/Local
External
Conceptual
MDBS: 5MDBS: 5--Level SchemaLevel Schema
To support the main characteristics of MDBS, a 5-level schema architecture is required
an extended version of the 3-level schema
1. External schema
2. Federated schema
an integration of multiple export schemas
3. Export schema
a subset of the component schema that is available to the FDBS
4. Component schema
the conceptual schema of a component
5. Local schema
DBMS
DB
Centralized DBS
MDBMS
DB DB
DBMS DDBMS
DB
MDBS: 5MDBS: 5--Level SchemaLevel Schema
DBDB--Component 1Component 1 DBDB--Component 2Component 2
MDBMS
DB DB
DBMS DDBMS
DB
Internal/Local
External
Conceptual
ExternalExternal External External
Federated
Export
Component1
Local
Federated Federated
Export
Component2
Local
Export

SE352b 3-Mar-06
ThreeThree--Schema ArchitectureSchema Architecture(Cont.)(Cont.)
DATABASE
End User End User
External LevelExternal LevelExternal Schema
VIEWExternal Schema
VIEWExternal Schema
VIEWExternal Schema
VIEW
Conceptual LevelConceptual Level Conceptual SchemaConceptual Schema
Internal LevelInternal Level Internal SchemaInternal Schema
Views Views Example…Example…
Section Id
YearSemesterGradeCourse Number
Student TranscriptStudent NameTRANSCRIPT
Database
Data generated on the flyUsing subject areas entitiesData generated on the flyUsing subject areas entities
Brown
Smith
13599FallACS3380
10299SpringBCS3320
9298FallACS1310
8598FallAMATH2410
11299FallBMATH2410
11999FallCCS1310
Database Definition
(MetaMeta--DataData)
DepartmentCreditCourse NumberCourse NameCourse NameCOURSE
InstructorYearYearSemesterSemesterCourse NumberSection IdentifierSection IdentifierSECTION
MajorClassStudent NumberNameNameSTUDENT

SE352b 3-Mar-06
Data Models
Schemas
Schema Architecture
DBMS Languages
Business Data Types
Query Processing
Business Data TypesBusiness Data Types
Operational Data
Informational Data DatabaseSystem
OperationalDatabase
Tools
InformationalDatabase
Tools

SE352b 3-Mar-06
Operational DataOperational DataThe data used to run the day-to-day business
Typically stored in a relational database
possibly, in legacy hierarchical or flat file formats as well
Some characteristicsUpdated often and through online transactions
Non-historical data (not more than three to six months old)
Optimized for transactional processing
Highly normalized in the relational database for efficient update, maintenance, and integrity
Informational DataInformational Data
Or information is a representation of the data in a way makes analysis much easier
Analysis can be in the form of decision support
executive information systems
report generation
more in-depth statistical analysis
Created from the wealth of existing operational data

SE352b 3-Mar-06
RelationalRelational Database DesignDatabase Design
∗ Conceptual design∗ ER Model is used at this stage to capture
the core business/application concepts and rules∗ which is then translated to a relational schema
• Schema refinement• Normalization: to tune the schema for efficiency
• check relational schema for redundancies and related anomalies
Physical database design tuning• Consider typical workloads and further refine the database design
Conceptual DesignConceptual Design
• What?• the entitiesentities and relationshipsrelationships in the enterprise
•• informationinformation about these entities and relationships should we store in the database
• the integrity constraintsintegrity constraints that hold
• Represent this information pictorially in ER diagramsER diagrams,

SE352b 3-Mar-06
Conceptual Design Conceptual Design ER Diagrams ER Diagrams ---- the basicsthe basics
Entitiesreal world “objects”,
e.g. Students, Courses, Routes, Climbers. Entity sets are drawn as rectangles:
Attributesthings typically used as column names,
e.g. Name, Age, Height.
Relationshipsrelationships between entities,
e.g. a student enrolls in a course, a climber climbs a route, etc. :
ER: ExampleER: Example
IDEF1X Notationhttp://www.idef.com/IDEF1X.html
Account ID
ACCOUNT
Account Type
Own
CLIENT
Client Name
Client IDClient ID

SE352b 3-Mar-06
Relational:Relational:DefinitionsDefinitions
Keya set of attributes of a relation whose values are unique within the relation
If there is more than one key, they are called Candidate KeysCandidate Keys
Prime attributePrime attributeone which is a member of any key
Nonprime attribute
one which is not prime
primary keyarbitrarily designated candidate keydesignated candidate key
all other candidate keys are Secondary KeysSecondary Keys
Client IDClient IDPrimary KeyNot Nullifyable
ER: ER: Identity & Functional DependencyIdentity & Functional Dependency
IDEF1X Notation
Account ID
ACCOUNT
Account Type
CLIENT
Account ID
ACCOUNT
Client NameAccount Type
Client IDOwn
Client ID (FK)
OwnClient ID (FK) Foreign Key
CLIENT
Nonprimeattributes
Client Name
Client ID
Not Nullifyable
Nullifyable

SE352b 3-Mar-06
Associative EntitiesAssociative Entities
An associative entity is a relation that contains data, and so may be treated as an entity.
Client ID
CLIENT
Client Name
Account ID
ACCOUNT
Account Type
Resolved many-to-many Relationship
PP
Role
ROLEClient IDAccount ID
Role Type
P P
Translating ER to Relational SchemaTranslating ER to Relational Schema
Each entity becomes a a tabletable (relation)
The attributes associated with each entity become attributesattributes of the relationThe key is nonnon--nullifiednullified attributesattributes
The keys of the associated entities with dependency are foreign keysforeign keys

SE352b 3-Mar-06
ER: ER: Identity & Functional DependencyIdentity & Functional Dependency
IDEF1X Notation
Account ID
ACCOUNT
Account Type
OwnClient ID (FK) Foreign Key
CLIENT
Nonprimeattributes
Client Name
Client ID
Translating to RelationsTranslating to Relations
CREATE TABLE CLIENT (Client_Number VARCHAR2(20) NOT NULL,Client_Name VARCHAR2(20) NULL,
);
CREATE TABLE CLIENT CLIENT (Client_Number VARCHAR2(20) NOT NULL,Client_Number VARCHAR2(20) NOT NULL,Client_Name VARCHAR2(20) NULL,
);
CREATE TABLE ACCOUNT (Account_Number VARCHAR2(20) NOT NULL,Client_Number VARCHAR2(20) NOT NULL,Account_Type VARCHAR2(20) NULL,
);
CREATE TABLE ACCOUNTACCOUNT (Account_Number VARCHAR2(20) NOT NULL,Account_Number VARCHAR2(20) NOT NULL,Client_Number VARCHAR2(20) NOT NULL,Client_Number VARCHAR2(20) NOT NULL,
Account_Type VARCHAR2(20) NULL,);
Account IDAccount ID
ACCOUNT
Account Type
OwnClient ID (FK)Client ID (FK) Foreign Key
CLIENT
Nonprimeattributes
Client Name
Client ID

SE352b 3-Mar-06
Database Management
System
Database SystemDatabase System
Database
Application
Data Design vs. ImplementationData Design vs. ImplementationER vs. Relational DatabaseER vs. Relational Database
Entity
Attribute
Instances
Relationship
Data Architecture(Logical Model)
Inv.Lee456
Reg.Smith123
Account Type
Client IDAccount ID
ImplementationImplementationDesignDesign
⇒ Table
⇒ Columns
⇒ Rows
⇒ Foreign Keys
Column
Row
ACCOUNT Table
Client ID
CLIENT
Client Name
Account IDACCOUNT
Account Type
POwnClient ID
Data Models
Schemas
Schema Architecture
DBMS Languages
Business Data Types
Query Processing

SE352b 3-Mar-06
Quality of DB DesignQuality of DB Design
Begin by discussing good and bad relation schemasschemas
Informal measures of the quality of relation schema design
Semantics of the attributes
Reducing the redundant values in tuples
Reducing the null values in tuples
Define normal forms formal measures of the quality of schemas
restrictions on the form of relation schemas
Manuf is attribute of Car and Not of OwnerCarManuf is attribute of Car and Not of OwnerCar
Semantics of the Relation AttributesSemantics of the Relation Attributes
The elements of the schema should be easy to explain
Keep attributes from different entities and relationships distinctExample
OwnerCar: (OId,Oname, DLNum, CarId, Make, Manuf)OIdOnameDLNumCarIdMakeManuf
OwnerCar

SE352b 3-Mar-06
Irrelevant to the Owner
Redundant InformationRedundant Information
Consider the following :(123,Joe, 123456789,106, Dodge, Chrysler)
(223,Moe, 223456789, 107, Dodge, Chrysler)
The Manuf attribute is redundant!
This leads to difficulty in updates (Update Anomalies)e.g. changing the Manuf for owner with OId 123 requires also changing it for OId 223.
OwnerCar: (OId, Oname, DLNum, CarId, Make, Manuf)OwnerCar: (OId, Oname, DLNum, CarId, Make, Manuf)
Update AnomaliesUpdate Anomalies
Insertion anomaliesWhen inserting a new owner,
we must correctly insert the Manuf, or will create inconsistenciesCannot create a car without an owner
Deletion anomaliesDeletion of owner of a car
also deletes make and manufacturer of car
Deletion of owner of the last Dodgedeletes relationship between Dodge and Chrysler
Modification anomaliesChanging the make of a car requires consistency checkCannot change so that a Dodge is made by Ford
OwnerCar: (OId,Oname, DLNum, CarId, Make, Manuf)OwnerCar: (OId,Oname, DLNum, CarId, Make, Manuf)
(123,Joe, 123456789,106, Dodge, Chrysler)

SE352b 3-Mar-06
X Y is a full functional dependencyif the removal of any attribute Ai from X removes the dependency
Not (X - {Ai} Y)
X Y is a partial dependencyif some attribute Ai may be removed without removing the dependency
X - {Ai} Y
X Y is a full functional dependencyif the removal of any attribute Ai from X removes the dependency
Not (X - {Ai} Y)
X Y is a partial dependencyif some attribute Ai may be removed without removing the dependency
X - {Ai} Y
Normalization:Normalization:Definition of Functional DependencyDefinition of Functional Dependency
Functional dependency
a constraint between 2 sets of attributes from the database For each value of the first set there is a unique value of the second set
XX YY restricts the tuples that can be instances of the relation Rs.t. if t1 and t2 are instances of R
t1(X) = t2(X) then t1(Y) = t2(Y)For example, Client(CId, CName, CAddress)
{CId} {CName, CAddress}
A1A2
A3A4A5
R
X Y
} X
} YCId
CNameCAddress
Client
Normalization FormsNormalization Forms
A relation R (table) is in
1NF: if all attribute values are atomic (or indivisible)A relation that contains no repeating groups
2NF: If it is in 1NF and every nonprime attribute is fully functionally dependent on the primary key of R
3NF: if it is in 2NF andthere is no nonprime attribute that is functionally dependenton a non-key set of attributes

SE352b 3-Mar-06
UnUn--normalized Tablenormalized Table
Key List List List CompositeAccountant
NumberSkill
NumberSkill
Category ProfAccountant
NameAccountant
AgeOffice
NumberOffice City
Office Supervisor
21 113 Systems 3 Alice Adams 55 52 NYC Brown113 Systems 5179 Tax 1204 Audit 6
50 179 Tax 2 Charlie Cody 40 44 LA Green
148 Consulting 6179 Tax 6
LA Green
NYC Brown
35 Doug Baker
77 Doug Doe 52 52
32 44
Instances with Repeated GroupsInstances with Repeated Groups
1NF Table1NF Table
Accountant Number
Skill Number
Skill Category Prof
First Name
Last Name
Accountant Age
Group Number
Group City
Group Supervisor
21 113 Systems 3 Alice Adams 55 52 NYC Brown35 113 Systems 5 Doug Baker 32 44 LA Green35 179 Tax 1 Doug Baker 32 44 LA Green35 204 Audit 6 Doug Baker 32 44 LA Green50 179 Tax 2 Charlie Cody 40 44 LA Green77 148 Consulting 6 Doug Doe 52 52 NYC Brown77 179 Tax 6 Doug Doe 52 52 NYC Brown
Key
{Account Number, Skill Number} {Skill Category, Prof, …}{Account Number, Skill Number} {Skill Category, Prof, …}X Y

SE352b 3-Mar-06
2NF Table2NF Table
Key
Accountant Number
First Name Last Name
Accountant Age
Group Number
Group City
Group Supervisor
21 Alice Adams 55 52 NYC Brown35 Doug Baker 32 44 LA Green50 Charlie Cody 40 44 LA Green77 Doug Doe 52 52 NYC Brown
Accountant Table
KeySkill
NumberSkill
Category113 Systems179 Tax204 Audit148 Consulting
Skill Table
Accountant Number
Skill Number Prof
21 113 335 113 535 179 135 204 650 179 277 148 677 179 6
Proficiency TableKey
2NF Table2NF Table
Key
Accountant Number
First Name Last Name
Accountant Age
Group Number
Group City
Group Supervisor
21 Alice Adams 55 52 NYC Brown35 Doug Baker 32 44 LA Green50 Charlie Cody 40 44 LA Green77 Doug Doe 52 52 NYC Brown
Accountant Table
3NF: if it is in 2NF and there is no nonprime attribute that is functionally dependent on a non-key set of attributes

SE352b 3-Mar-06
3NF Table3NF Table
KeyGroup
NumberGroup
CityGroup
Supervisor44 LA Green52 NYC Brown
Group TableKey
Accountant Number
First Name
Last Name
Accountant Age
Group Number
21 Alice Adams 55 5235 Doug Baker 32 4450 Charlie Cody 40 4477 Doug Doe 52 52
Accountant Table
KeySkill
NumberSkill
Category113 Systems179 Tax204 Audit148 Consulting
Skill Table
Accountant Number
Skill Number Prof
21 113 335 113 535 179 135 204 650 179 277 148 677 179 6
Proficiency TableKey
NormalizationNormalization
Table with repeating groups
Table with repeating groups
1NF1NF
Remove repeating groupsRemove repeating groups
2NF2NF
Remove partial dependencyRemove partial dependency
3NF3NF
Remove transitive dependencyRemove transitive dependency
Each attribute relies on the key, the whole key, and nothing but the key
so help me codd!”
Each attribute relies on the Each attribute relies on the keykey, , the the whole keywhole key, and nothing but the , and nothing but the keykey
so help me so help me coddcodd!”!”

SE352b 3-Mar-06
Referential IntegrityReferential IntegrityIntegrity Constraints:
A set of (business) rules that address the validity of references by one object in DB to some other object(s) in the DB
Insertion Rule
A row should not be inserted in the referencing table unlessthere already exists a matching entry in the referenced table
Deletion Rule
A row should not be deleted from the referenced table if there is a matching row(s) in the referencing table
Enforcing Referential Integrity:Referential integrity options are declared when relational tables are defined
then, enforced by DBMS
Data Models
Schemas
Schema Architecture
DBMS Languages
Business Data Types
Query Processing

SE352b 3-Mar-06
SQLSQLStructured Query Language
ANSI and ISO standarde.g., SQL2 or SQL-92
SQL isa data definition language (DDL), and
a data manipulation language (DML), and
a programming (4th generation) language
We can use SQL forLogical database specification (database schema definitions)
Physical database specifications (indexes, etc.)
Querying database contents
Modifying database contents
SQL as SQL as DDLDDL::Create Table StatementCreate Table Statement
create table Customer (accountId int,lastName varchar(32),firstName varchar(32),street varchar(100),city varchar(32),state char(2),zipcode varchar(9)
);
Note that SQL has specific types

SE352b 3-Mar-06
Data types in SQLData types in SQL
integer integer, int, smallint, long floating point float, real, double precision
Numeric types
formatted decimal(i,j), dec(i,j)fixed length char(n), character(n) Character-string
types varying length varchar(n), char varying(n), character varying(n)
fixed length bit(n) Bit-string types varying length bit varying(n)
Date and time types
date, time, datetime, timestamp, time with time zone, interval
character long varchar(n), clob, text Large types binary blob
)
)
SQL as SQL as DMLDMLInsert Into values;
Insert IntoInsert Into employee (first, last, age, address, city, state) valuesvalues('Luke', 'Duke', 45, '2130 Boars Nest', 'Hazard Co', 'Georgia');
Delete from where Operator [and|or Operator ]; [ ] = optional
Delete fromDelete from employee wherewhere lastname = 'May';
Update set [

SE352b 3-Mar-06
Relational Operations in SQLRelational Operations in SQLSelect statement
select from where
Projection in SQL using select clause
SelectSelect title fromfrom Movies
Selection in SQL using where clause
select * from Customer wherewhere lastName = 'Doe'
select distinctdistinct lastName, firstName from Customer
no duplicates with distinct
SQL as SQL as VDLVDLProducts and Joins in SQL vs. Products and Joins in SQL vs. ViewsViews
Cartesian product in SQL using from clauseSelect * from Employee, Timecard
Join using from and where clauses
Select * from Employee, Timecard whereEmployee.sin = Timecard.sin
Create View Test As
Create View EmployeeCard As
Select * from Employee, Timecard where Employee.sin = Timecard.sin;
Create View EmployeeCard As
Select * from Employee, Timecard where Employee.sin = Timecard.sin;
create table Employee (Sin int,lastName varchar(32),firstName varchar(32),street varchar(100),city varchar(32),state char(2),zipcode varchar(9)
)
create tabletable Employee (Sin int,lastName varchar(32),firstName varchar(32),street varchar(100),city varchar(32),state char(2),zipcode varchar(9)
)

SE352b 3-Mar-06
ThreeThree--Schema ArchitectureSchema Architecture(Cont.)(Cont.)
DATABASE
End User End User
External LevelExternal LevelExternal Schema
VIEWExternal Schema
VIEWExternal Schema
VIEWExternal Schema
VIEW
Conceptual LevelConceptual Level Conceptual SchemaConceptual Schema
Internal LevelInternal Level Internal SchemaInternal Schema
EmployeeCard
Employee
Views Views Example…Example…
Section Id
YearSemesterGradeCourse Number
Student TranscriptStudent NameTRANSCRIPT
Database
Data generated on the flyUsing subject areas entitiesData generated on the flyUsing subject areas entities
Brown
Smith
13599FallACS3380
10299SpringBCS3320
9298FallACS1310
8598FallAMATH2410
11299FallBMATH2410
11999FallCCS1310
Database Definition
(MetaMeta--DataData)
DepartmentCreditCourse NumberCourse NameCourse NameCOURSE
InstructorYearYearSemesterSemesterCourse NumberSection IdentifierSection IdentifierSECTION
MajorClassStudent NumberNameNameSTUDENT

SE352b 3-Mar-06
SQL: 4SQL: 4thth Generation PLGeneration PLNested QueriesNested Queries
Nested select query
Select videoId, dateAcquiredfrom Videotape where videoId in (
select videoId from Rental where dateRented=‘1/1/03’)
compare with
Select v.videoId, dateAcquiredfrom Videotape v, Rental rwhere v.videoId = r.videoId and
dateRented=‘1/1/03’)
Exists and Unique QueriesExists and Unique Queries
Find employees who have no time cards
Select firstName, lastName from Employee ewhere not exists
(select * from TimeCard t where e.sin=t.sin)
Find managers who have exactly one time card
select firstName, lastName from Employee ewhere unique
(select * from TimeCard t where t.sin=e.sin)and exists
(select * from Store where sin=manager)

SE352b 3-Mar-06
Aggregate FunctionsAggregate Functions
How many employees work at Store 3
select countcount (*) from WorksAt
where storeId=3
What is the average hourly rate of all hourly employees
select averageaverage(hourlyRate) from HourlyEmployees
How many different salaries are there?
select count (distinct salary) from SalariedEmployee
Data Models
Schemas
Schema Architecture
DBMS Languages
Business Data Types
Query Processing

SE352b 3-Mar-06
Database Management
System
Database SystemDatabase System
Data
ApplicationQuery ProcessingQuery Processing
How to represent relational DB?Each table is a file
File is a random access collection of records
Query is executed by reading records from files
Read record, create object in memory
Process object
Write result as a file of records or
keep in memory
Data file
4625
Byte address0
File contentsAnimal House&189&comedy&@Duck Soup&987&comedy&@Elizabeth&450&costume drama&@
IndexesIndexes
If selection queries are frequent, sorting the file or building indexes is important
Hash-based indexes only good for equality search
Sorted files and tree-based indexes best for range searchalso good for equality search
Data file
4625
Byte address0
Index to file
KeymovieId
Address
189450987
04625

SE352b 3-Mar-06
IndexesIndexes
An index on a file speeds up selections on the search key fields for the index
Any subset of the records of a relation can be the search key for an index on the relation
Search key is not the same as the relation key
An index contains a collection of data entries, and
supports efficient retrievalof all data entries with a given key value
Data file
4625
Byte address0
Index to file
KeymovieId
Address
189450987
04625
B+ TreeB+ Tree
B+ tree index: Balanced treesThe Most Widely Used Index
Ordered sequential file, linked list of ordered records
Good for range queriesSearch index for first record in range
Read data file sequentially
(linked list order) for rest of records
Insert/delete
at log f N cost;
(f = fanout, N = # leaf pages)
keep tree height-balanced
B+ treeP Y
A B C
· · · ·
Q S U W
· · · ·
X Y
· ·
H K M P
· · · ·
E G
· ·
C G P W Y
A ... B ... E ... G ...
Q ... S ...
C ... H ... P ...
W ...X ... Y ...Data file
First level
Third level
Second level

SE352b 3-Mar-06
Example: Processing a Range QueryExample: Processing a Range Query
select * from Customer where accountId >= 101 and accountId < 300select * from Customer where accountId >= 101 and accountId < 300
347 903
10 24 35
• • •
700 767 876 901
• • • •
902 903
• •
123 200 246 347
• • • •
101 110
• •
35 110 347 901 903
Data file
10 ... 24 ... 101 ... 110 ...35 ...
123 ... 200 ... 246 ... 347 ... 700 ... 767 ...
902 ... 903 ...876 ... 901 ...
B+ tree index for accountId
B+ Trees in PracticeB+ Trees in Practice
Typical order: 100. Typical fill-factor: 67%.average fanout = 133
Typical capacities:Height 4: 1334 = 312,900,700 records
Height 3: 1333 = 2,352,637 records
Can often hold top levels in buffer pool:Level 1 = 1 page = 8 Kbytes
Level 2 = 133 pages = 1 Mbyte
Level 3 = 17,689 pages = 133 MBytes

SE352b 3-Mar-06
TransactionsTransactions
A transaction is
a sequence of read and write operations on data items Logically, functions are treated as one unit of work
should either be done entirely or not at all
if it succeeds,the effects of write operations persist (commit);
if it fails,no effects of write operations persist (abort)
these guarantees are made despite concurrent activity in the system, and despite failures that may occur
Desirable Properties of Transactions: Desirable Properties of Transactions: ACIDACID
Atomicitythe property of a transaction that all of the updates are successful,or there is no update at all.
Consistencyeach transaction should leave the database in a consistent state
Properties such as referential integrity must be preserved
Isolationeach transaction when executed concurrently with other transactions should have the same affect as if it had been executed by itself
Durabilityonce a transaction has completed successfully, its changes to the database should be permanent.
Even serious failures should not affect the permanence of a transaction

SE352b 3-Mar-06
Transactions in SQLTransactions in SQL
A transaction begins when any SQL statement that queries the DB begins
To end a transaction,
the user issues
a Commit or
Rollback statement
OperationsBegin
Read
Write
Commit
Rollback
Example of TransactionExample of Transaction
Begin transaction
videoId video1 = select id of a copy of "Star Wars"
if (video1 == null) rollback transaction
insert row into Reservation for video1
videoId video2 = select id of a copy of "Return of the Jedi"
videoId video3 = select id of a copy of "The Empire Strikes Back"
commit transaction
Begin transaction
videoId video1 = select id of a copy of "Star Wars"
videoId video2 = select id of a copy of "Return of the Jedi"
videoId video3 = select id of a copy of "The Empire Strikes Back"
commit transaction

SE352b 3-Mar-06
Data Models
Schemas
Schema Architecture
DBMS Languages
Business Data Types
Query Processing
Interacting with Interacting with DBsDBs::Client Server ArchitectureClient Server Architecture
UserInterface Application
MiddlewareMiddlewareMiddleware
layer
DatabaseServer Database
Server
DatabaseServer layer
DatabaseServer
User and ApplicationClient layer
UserInterface Application
DBApplication
DBApplication

SE352b 3-Mar-06
Interacting with Interacting with DBsDBs::Java EnvironmentJava Environment
MiddlewareLayerMiddlewareMiddlewareLayerLayer
DatabaseServer LayerDatabaseDatabaseServer LayerServer Layer
Client LayerClient LayerClient Layer JavaJavaProgramProgram
java.sqljava.sqlpackagepackage
JDBC-ODBCbridge
ODBC databaseclient
Oracle Databaseclient
Middlewareclient
Middlewareserver
Oracleserver
Accessserver
Sybaseserver
Oracle Databaseclient
Sybase Databaseclient
Oracle ODBCclient
Access ODBCclient
JDBC packageJDBC package JDBC packageJDBC package JDBC packageJDBC package
Java Database Connectivity (JDBC)
Interacting with Interacting with DBsDBs::Java EnvironmentJava Environment
Package java.sql includes interfaces
Driver: supports the creation of a data connection
Connection: represents the connection between a Java client and an SQL database server
DatabaseMetaData: contains information about the database server
Statement: includes methods for executing text queries
PreparedStatement: represents a pre-compiled and stored query
CallableStatement: used to execute SQL stored procedures
ResultSet: contains the results of the execution of a select query
ResultSetMetaData: contains information about a ResultSet, including the attribute names and types.

SE352b 3-Mar-06
/* CIA.java/* CIA.javaFrom http://sqlzoo.net By Andrew CummingFrom http://sqlzoo.net By Andrew Cumming
*/*/import java.sql.*;import java.sql.*;public class CIA{public class CIA{public static void main(String[] args){public static void main(String[] args){Connection myCon;Connection myCon;Statement myStmt;Statement myStmt;try{try{Class.forName("com.mysql.jdbc.Driver").newInstance();Class.forName("com.mysql.jdbc.Driver").newInstance();# Connect to an instance of mysql with the follow details:# Connect to an instance of mysql with the follow details:# machine address: pc236nt.napier.ac.uk# machine address: pc236nt.napier.ac.uk# database : gisq# database : gisq# user name : scott# user name : scott# password : tiger# password : tigermyCon = DriverManager.getConnection(myCon = DriverManager.getConnection(
"jdbc:mysql://pc236nt.napier.ac.uk/gisq""jdbc:mysql://pc236nt.napier.ac.uk/gisq""scott","tiger");"scott","tiger");
myStmt = myCon.createStatement();myStmt = myCon.createStatement();ResultSet result = myStmt.executeQuery(ResultSet result = myStmt.executeQuery(
"SELECT * FROM cia WHERE population>200000000");"SELECT * FROM cia WHERE population>200000000");while (result.next()){while (result.next()){System.out.println(result.getString("name"));System.out.println(result.getString("name"));
}}myCon.close();myCon.close();
}}catch (Exception sqlEx){catch (Exception sqlEx){System.err.println(sqlEx);System.err.println(sqlEx);
}}}}
}}
#!C:/perl/bin/perl#!C:/perl/bin/perluse CGI qw(:standard);use CGI qw(:standard);use Mysql;use Mysql;
print header();print header();
#Import the CGI parameters into the $Q structure#Import the CGI parameters into the $Q structureimport_names();import_names();
#Connect to Andrew's MySQL server at Napier University#Connect to Andrew's MySQL server at Napier Universitymy $dbh = DBI->connect("dbi:mysql:database=gisq;host=pc236nt.napier.ac.uk;port=3306",my $dbh = DBI->connect("dbi:mysql:database=gisq;host=pc236nt.napier.ac.uk;port=3306",
"scott", "tiger");"scott", "tiger");
my $sth = $dbh->prepare("SELECT DISTINCT region FROM cia");my $sth = $dbh->prepare("SELECT DISTINCT region FROM cia");$sth->execute;$sth->execute;print "Here are some regions\n";print "Here are some regions\n";while (my ($region) = $sth->fetchrow_array()){while (my ($region) = $sth->fetchrow_array()){
print "$region
\n";print "$region
\n";}}
if ($Q::region) {if ($Q::region) {print "Here are the countries of $Q::region";print "Here are the countries of $Q::region";my $sth = $dbh->prepare("SELECT name, population FROM cia where region=?");my $sth = $dbh->prepare("SELECT name, population FROM cia where region=?");$sth->execute($Q::region);$sth->execute($Q::region);while (my ($name,$pop) = $sth->fetchrow_array()){while (my ($name,$pop) = $sth->fetchrow_array()){
print "$name $pop
\n";print "$name $pop
\n";}}
}}
$dbh->disconnect;$dbh->disconnect;

SE352b 3-Mar-06
Interacting with Interacting with DBsDBs::Web Server ArchitectureWeb Server Architecture
Web ServerMiddleware
layer
DatabaseServer Database
ServerDatabase
Server
User and ApplicationClient layer
WebBrowser
DBApplication
WebBrowser
WebBrowser
WebBrowser
DBApplication
FileSystems
DatabaseServer layer
Web Server Web Server ArchitecturesArchitectures
The architecture type depends on kind and number of servers involved
Different archictures different advantages and disadvantages
Generally we can distinguish between
2-tier architecture
3-tier architecture
n-tier architecture
What matters: SPEEDSPEED

SE352b 3-Mar-06
Advantages:easy and fast to setup
easy to administrate
Disadvantages:not fail safe (single point of failure)
scales badly on high loads
22--tier Architecturetier ArchitectureWeb server + module connecting to database
HTTP-Request
HTML-File Module
Directory
1
2
Web-Server
DB
33--tier Architecturetier ArchitectureWeb server + application server connecting to database
1
3
2
Web Server[Cluster]
Application Server[Cluster]
Other Servers[Cluster]
DBRepl.
DBDB DB
Advantages:better scalabilty
more reliable
through various mechanisms
offers better load balancing
Disadvantages:complicated to set up an maintain

Software Tools - Instructinstruct.uwo.ca/engin-sc/se352b/notes/HG-SE352Lect-W06... · 2006-03-04 · SE352b 3-Mar-06 (c) Hamada Ghenniwa, ECE, UWO 3 Feb 24, 2006 SE352b, ECE,UWO,

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