JDBC - Java Database Connectivity
What is JDBC?
JDBC provides Java applications with access to most
database systems via SQL
The architecture and API closely resemble Microsoft's
ODBC (Open DataBase Connectivity)
JDBC 1.0 was originally introduced into Java 1.1
JDBC 2.0 was added to Java 1.2 and so on..
JDBC 4.0 is the latest version.
JDBC classes are contained within the java.sql &
javax.sql packages.
There are few classes
There are several interfaces
JDBC Architecture
With JDBC, the application programmer uses the JDBC
API
The developer never uses any proprietary APIs
•
Any proprietary APIs are implemented by a JDBC driver
•
There are 4 types of JDBC Drivers
Java Application
JDBC API
JDBC DriverManager
JDBC Driver
JDBC Driver
JDBC Architecture
Application
•
•
•
•
JDBC
Driver
Java code calls JDBC library
JDBC loads a driver
Driver talks to a particular database
Can have more than one driver -> more than one
database.
JDBC Classes
DriverManager
Manages JDBC Drivers
Used to Obtain a connection to a Database
Date
Used to Map between java.util.Date and the SQL DATE type
•
Time
Used to Map between java.util.Date and the SQL TIME type
JDBC Interfaces
Driver
All JDBC Drivers must implement the Driver interface. Used to obtain a
connection to a specific database type
•
Connection
Represents a connection to a specific database
Used for creating statements
Used for managing database transactions
Used for accessing stored procedures
Used for creating callable statements
ResultSet
Represents the result of an SQL statement
Provides methods for navigating through the resulting data
JDBC Interfaces
Statement
Used for executing SQL statements against the database
•
PreparedStatement
Similar to a stored procedure
An SQL statement (which can contain parameters) is compiled and
stored in the database
CallableStatement
Used for executing stored procedures
JDBC Drivers
There are 4 types of JDBC Drivers
Type 1 - JDBC-ODBC Bridge
Type 2 - JDBC-Native Bridge
Type 3 - JDBC-Net Bridge
Type 4 - Direct JDBC Driver
Type 1 only runs on platforms where ODBC is available
ODBC must be configured separately
Type 2 Drivers map between a proprietary Database API
and the JDBC API
Type 3 Drivers are used with middleware products
Type 4 Drivers are written in Java
In most cases, type 4 drivers are preferred
Client
Application GUI
Database Server
JDBC API
Network Interface
SQL Results
SQL Requests
SQL Results
SQL Requests
Network Connection
JDBC API defines a set of interfaces and classes to be used
for communicating with a database.
Client
Application
Database Server
JDBC Driver
Database Libraries
Network Interface
SQL Results
SQL Requests
SQL Results
SQL Requests
Network Connection
JDBC Driver: translates java into SQL.
JDBC drivers are implemented by database vendors.
JDBC supports the ANSI SQL92 Entry Level standard.
JDBC Driver Types:
Driver Type
Description
1. ODBC-JDBC Bridge
Map JDBC calls to ODBC
driver calls on the client.
2. Native API-Part Java
Maps JDBC calls to native
calls on the client.
3. JDBC Network-All Java
Maps JDBC calls to network
protocol, which calls native
methods on server.
4. Native Protocol-All Java
Directly calls RDBMS from
the client machine.
Type I: JDBC-ODBC Bridge Driver
Client
Application
JDBC Driver
Local Disk
ODBC Driver
Network Interface
SQL Requests
SQL Results
Proprietary Database Protocol
Network Interface
Stand-Alone Applications run on Local Machine
JDBC Driver: translates java calls into ODBC calls.
Harder to debug, slower, not work for applets.
Inexpensive, readily available.
Database
Server
Type II: Native-API-Partly Java Driver
Client
Application
JDBC Driver
Local Disk
Native Database Libraries
(Call Level Interface)
Network Interface
SQL Requests
SQL Results
Proprietary Database Protocol
Network Interface
JDBC Driver: use local libraries to communicate
with database server. Java calls are translated into
local CLI calls.
Faster than the ODBC bridge, not work for applets.
Database
Server
Type III: JDBC-Net-All-Java Driver
Client
Application
JDBC Driver
(Client)
Local Disk
Network Interface
SQL Requests
SQL Results
JDBC Driver Network Protocol
Network Interface
•JDBC Driver: client calls are translated into
driver-specific network protocol.
•JDBC Driver: server listener translates the
requests into CLI calls at server site.
•All database-specific code resides on the
server.
•JDBC driver network protocol is not
Server
JDBC Driver
(Server Listener)
Database
Native Database Libraries
(Call Level Interface)
Type IV: Native-Protocol-All-Java Driver
Client
Application
Local Disk
JDBC Driver
Network Interface
SQL Requests
SQL Results
Proprietary DB Protocol (in Java)
Network Interface
•JDBC Driver: 100% java and use no CLI
native libraries.
•Support applets containing the driver to be
downloaded over the network, I.e., applets can
communicate directly with the database.
Server
Database
JDBC Drivers (Fig.)
Type I
“Bridge”
JDBC
Type II
“Native”
Type III
“Middleware”
Type IV
“Pure”
ODBC
ODBC
Driver
CLI (.lib)
Middleware
Server
SQL Types/Java Types Mapping
SQL Type
Java Type
CHAR
VARCHAR
LONGVARCHAR
NUMERIC
DECIMAL
BIT
TINYINT
SMALLINT
INTEGER
BIGINT
REAL
FLOAT
DOUBLE
BINARY
VARBINARY
DATE
TIME
String
String
String
java.Math.BigDecimal
java.Math.BigDecimal
boolean
int
int
int
long
float
double
double
byte[]
byte[]
java.sql.Date
java.sql.Time
Steps
To execute a statement against a database, the following flow is observed
Load the driver (Only performed once)
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Obtain a Connection to the database (Save for later use)
Connection con = DriverManager.getConnection("jdbc:odbc:DSN");
Obtain a Statement object from the Connection
Statement st=con.createStatement()
PreparedStatement pst=con.prepareStatement(String sql)
Use the Statement object to execute SQL. Updates, inserts and deletes
return Boolean. Selects return a ResultSet
ResultSet rs=st.executeQuery(String sql)
Navigate ResultSet, using data as required
public int getInt(int columnNumber)
public String getString(String columnName)
Close Connection.
con.close()
import java.sql.*;
class Conn1
{
public static void main(String[] args)
{
ResultSet rs;
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection c=DriverManager.getConnection("jdbc:odbc:mydsn");
Statement st=c.createStatement();
rs=st.executeQuery("select * from stud1");
System.out.println("Name" +"\t"+"Roll");
while(rs.next())
{
System.out.println(rs.getString("Name")+"\t"+rs.getInt("Roll"));
}
c.close();
}
catch(Exception e)
{
System.out.println(e);