JDBC / ODBC

JDBC is the java API that facilitate interaction of a java application with the DBMS.

FIRST APPROACH:

Interact with

DBMS using the interface

Interface for

human user

Data

Application

API for application

API provided by the vendor

to interect

with DBMS. DBMS Package

• Problem of this approach that is problem of using vendor specific API is that Application becomes dependent on a particular API . If Data Base to be change than changes has to be made in the application apart from this for each data base A new API has to be learned.

• ODBC• Open data base connectivity is a common API that is

design in “C” & facilitate interaction of application with data bases using a single API.

ODBC driver or

Definition of ODBC functions

provided by vendors.

Data

Database pkg

Application

Set of functions declared in C that are used by the application developer to

interact with DBMS

Uses ODBC to interact

Vendors provides implementation of these function

ODBC

These Uses of function to write connectivity code

Interface for

human user

Set of java interfaces provided by sun

microsystem to facilitate interaction of java Application with

databases

Application

JDBC driver or

implementation of

JDBC interfaces provided

by vendor

Uses JDBC to interact

JDBC

Vendor provides implementation s of

these interfaces

Application developer uses these interfaces to e\write

connectivity code

• Implementation of JDBC interfaces is to be provided by vendors different vendors provides implementation in a different way depending upon the implementation of JDBC interfaces provided by vendor we have four type of JDBC driver.

• TYPE-1 Driver • 1) type 1 or (JDBC-ODBC bridge -driver ):(in this

implementation vendors defines classes for JDBC interfaces and invoke ODBC functions from these classes.

Java Application

JDBC Driver

ODBC Driver

JDBC –ODBC

Bridge

Type1 or JDBC(ODBC)

bridge driver

Advantages & disadvantages • 1)From the implementation point of view this is the

simplest driver.• Disadvantage:- 1)ODBC driver is required for each

machine on which Application is to be executed. • 2) degraded performance is obtain because for each

database operation various conversion are perform.• TYPE-2 Driver • Type-2 driver or native java –driver

Java Application

JDBC Driver

Native API

• In this implementation function of native library provided by vender are invoke from the java classes .

• Advantages: 1) better performance is obtained as compared to type 1.

• 2) ODBC Driver is not required.• Disadvantages: Native Driver is required for each

machine on which application is to executed.• TYPE-3 • It is represents a middle ware that is used to map

multiple data sources using different Type-2 drivers.

Java application 1 Java Application2

JDBC Driver Java Driver

Type-2 Driver for Data server 1

Type-2 Driver for Data server 2

Type-2 Driver for Data source 1n

TYPE-3/Native driver

• Advantage: type-2 driver for each data source need not be installed on each machine.

• Disadvantages: an additional middleware is required.

• Type-4 (pure java driver )• Type-4 driver are purely implemented in java that is

dependent of JDBC driver on ODBC or native function is removed.

Java application

JDBC

Pure java Native Driver

TYPE-4

• Advantage: 1) ODBC & native driver is not required .• 2) Better performance is obtained.• Disadvantage: implementation of driver is varies

from vender to vender . For each vender implementation classes provided by the vendor are required.

• JDBC API is provided in java.sql & javax.sql packages.

• Commonly used classes & interfaces of API:• 1)DriverManager (class )• 2) Connection Interf

ace

• 3)Statement• 4) PreparedStatement • 5) CollableStatement • 6) ResultSet(Application level cursor)• 7) ResultSetMetaData• 8) DataBaseMetaData• 9) sqlException (class )

Interface(2-8)

• 1) Driver manager class is responsible to identifying locating & using a specific driver for a database this class acts as a factory for connection object.

• 2) Connection: connection Interface provides the abstraction of a database connection & act as a factory of statement, prepared statement ,collable statement.

• 3)A statement is used to execute sql queries over a database connection & act as factory of Result Set.

• 4) Prepared statement provides the facility of executing parameterize queries.

• 5) collable Statement provide the facility of executing stored procedure & function .

• 6) represents an application curser i.e. result set is used to store result of a select query & act as a factory of result set meta data.

• 7) Result set meta data : provide the facility of obtaining information about the data contained in the result set.

• 8) provide the facility of obtaining information about the data base .

• 9)is the super class of all database related exception .

•

• Steps : to connect a java Application to data base:• 1) Explicitly load the driver class . • forName(): method of Class is used to load the driver

class .• In case of type-1.• Sun.jdbc.odbc.jdbcodbcDriver class is loded.• This class is provided by sun microsystem as part of

java library .• rt.jar • This class provides the name of connection class ,to

be used by the Driver manager to create a connection object as well as provides information required by the driver manager to establish a connection.

• e,.g. Class.forName(sun.jdbc.odbc.jdbcodbcDriver);• 2) create a connection object , getConnection()

factory method of DriverManager class is used to create a connection object.

• Public static connection getConnection(String connection string )throws sqlException;

• or public static connection getConnection(String connection string ,String user name, String Password)throws sqlexception.

• Connection String is used to provide information that is used by the DriverManager to establish a connection with a data source , formate of connection string for type-1 jdbc driver.

•

• Main protocol • Jdbc:odbc:DSN (data source name )• E.g. let there be a DSN named myDSN • Connection con=

DriverManager.getConnection(jdbc:odbc:myDSN);• Step3) create a statement object.• CreateStatement() factory method of connection

used for this purpose.• Public statement createStatement()throws

sqlException;• E.g. Statement stmt= con.CreateStatement();

• Step 4) Execute query statement interface provides following methods to execute queries.

• Public ResultSet executeQuery(String selectQuery)throws SQLException;

• public int executeupdate(String nonselectDML query)throws SQLexception.

• Public boolean execute(String nonDmLquery)throws SQLException;

• Steps 5: if select query is executed obtain data from the result set.

• Obtaining data from the result set is a two step process:

Beginning of result set

End of ResulSet

Result set

Initial position

of of record pointer in the

result set .

• 1) position the record pointer in the result set on a valid Record for this next() method of ResultSet interface is used . This method advance the position of record pointer by one record.

• next();• Public boolean next(); • 2) Read the value of a field of the current record as

a specified java type .• String mS-Aceess SQLServer Oracle • text varchar varchar

• Result set interface provides various method to obtain the value of a field as a java type. General signature of these methods is

• Public type getType(int index)throws SQLException • Actual method:• Public String getString(int index)throws

SqlException• Public int getInt(….);• Public date getDate();• Public float getFloat();• Etc…

• 6)close the connection :• A close method of connection interface used for

this purpose.• Public void close() throws sqlexception ;