1

Java DataBase Connectivity

JDBC

java.sql.*

2

Java DataBase Connectivity

• Draft release of JDBC spec (3/96)• Java API for executing SQL statements

(Since JDK 1.1)• Primary focus is to link with RDBMS and

OORDBMS systems• JDBC certification requires compliance with

ANSI SQL-2 spec. • Initial support for access to ODBC through

JDBC-ODBC bridge

3

What does JDBC do?

• Establish a connection with a database

• Send SQL statements to the database

• Process the results.

4

Client Server Models

5

JDBC Architecture

• Implemented in 2 specific layers

• Driver layer– Product / Vendor specific driver

implementations that convert JDBC syntax.

• Business Layer– JDBC DriverManager and associated classes

that connect Java Applications to appropriate drivers.

6

JavaSoft Framework

7

JDBC Drivers• JDBC-ODBC Bridge

– A “quick startup” was needed, and there were many ODBC compatible DBMSs in use.

• Native-API Driver– Relies on client access to database-access API. Only

partially implemented in Java, and uses API binary code.

• JDBC-Net Driver– Uses JDK network protocols to connect to server, which

then translated request into DBMS.

• Native Protocol - All Java Drivers– Uses DBMS network protocol to connect to database.

8

JDBC Interfaces(java.sql.*)

• java.sql.Driver– acceptsURL, connect, getPropertyInfo

• java.sql.Connection– createStatement, commit, prepareStatement, rollback

• java.sql.Statement– execute, executeUpdate, getResultSet,

getMoreResults

• java.sql.PreparedStatement– SetDate, setFloat, executeQuery, executeUpdate

9

JDBC Interfaces(java.sql.*)

• java.sql.CallableStatement– getByte, getTime, registerOutParameter

• java.sql.ResultSet– getBytes, getMetaData, next

• java.sql.ResultSetMetaData– getColumnName, getPrecision, isReadOnly

• java.sql.DatabaseMetaData– allTablesAreSelectable, getColumns,

getDatabaseProductName, supportsMultipleTransactions

10

Company table from zoo.mdb

11

SQL Queries• SELECT * FROM zoo.company;

– Will select all fields for all records from the “company” table in “zoo” database

• SELECT * FROM company WHERE state_cd = OR;– Will select all fields for records that have a state code of “OR”

• SELECT company_name, state_cd, postal_cd FROM company where postal_cd > 60000;– Will select 3 fields for all records that have a zip code larger

than 60000

12

SQL Queries• SELECT company_name, phone_nbr FROM company

where company_name LIKE ‘%Artist%’;– Will select 2 fields for all company names that contain the string

“Artist” preceded or followed by 0 or more char.

• String sql1 = “SELECT company_name, phone_nbr FROM company where company_name LIKE ‘%” + inputVar + “ %’ ”;– Above query changed to allow dynamic definition of comparator.

• INSERT INTO state_codes (state_cd, state_desc) VALUES ('MO', 'Missouri');– Will insert into the state_codes table a new record, with two fields -

state_cd, and state_desc, with values “MO”, and “Missouri”

13

JDBC Statement Types

• Statement (createStatement method)– Used for simple SQL statements

Connection con = DriverManager.getConnection(newurl);

Statement stmt = con.createStatement( );

String stmt = “Select * from retail_item where

retail_item_nbr = “ + somejavavariable;

ResultSet rs = stmt.executeQuery(stmt);

14

JDBC Statement Types

• PreparedStatement (prepareStatement method)– Used for SQL statements that require 1 or more input arguments.– Precompiled and stored for future use.

PreparedStatement pstmt =

con.prepareStatement("UPDATE EMPLOYEES

SET SALARY = ? WHERE ID = ?");

pstmt.setBigDecimal(1, 153833.00);

pstmt.setInt(2, 110592);

15

JDBC Statement Types

• CallableStatement (prepareCall method)– Extension of PreparedStatement that can also

execute SQL stored procedures and process results.

16

JDBC Connection process• Get Connection implementation from DriverManager• Get Statement from connection• Execute Statement• Process ResultSet returned from query• (For other statements check return value for number

of rows affected)• Repeat for as many Statements as needed.• Commit changes (if necessary)• Close statement

17

Company table from zoo.mdb

18

JDBC Application

import java.lang.*;import java.util.*;import java.sql.*;import sun.jdbc.odbc.*;import java.io.*;

public class sample1b{

public static void main(String arg[]) { int id, zip, nextRecord; float amount; java.sql.Date dt; String status, name; String result;

19

JDBC Application

try {//connect to ODBC database

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); String url = "jdbc:odbc:Zoo"; // connect Properties p = new Properties(); p.put("user", "student"); p.put("password","sql"); Connection con = DriverManager.getConnection(url,"student","sql"); // create Statement object Statement stmt = con.createStatement(); String sqlselect = "Select company_id, company_name, postal_cd" + " from company"; // run query ResultSet rs = stmt.executeQuery(sqlselect);

20

JDBC Application

// process results while(rs.next()) {

result = ""; id = rs.getInt(1); zip = rs.getInt(3); name = rs.getString(2); result = result.valueOf(id) + " "; result += result.valueOf(zip) + " "; result += name; System.out.println("Values are: " + result);

} System.out.println("\n\n");//create next (insert)query String sqlSelect2 = "INSERT INTO company

(company_id,company_name,address_1,city,state_cd,country_cd,postal_cd,phone_nbr) "+ "VALUES (9,'Bobs ISP','345 Main St','Grants Pass', 'OR', 'USA',97526,'(541)582-1234')";

21

JDBC Application

int ct = stmt.executeUpdate(sqlSelect2);System.out.println("Insert row: " + sqlSelect2.valueOf(ct));sqlselect = "Select company_id, company_name, postal_cd"

+ " from company"; // run query rs = stmt.executeQuery(sqlselect); // process results while(rs.next()) { result = ""; id = rs.getInt(1); zip = rs.getInt(3); name = rs.getString(2); result = result.valueOf(id) + " "; result += result.valueOf(zip) + " "; result += name; System.out.println("Values are: " + result); }

22

JDBC Application

//create last (delete) querySystem.out.println("\n\n");

sqlSelect2 = "DELETE FROM company WHERE company_name = 'Bobs ISP' "; ct = stmt.executeUpdate(sqlSelect2); System.out.println("Deleted row: " + sqlSelect2.valueOf(ct)); sqlselect = "Select company_id, company_name, postal_cd" + " from company"; // run query rs = stmt.executeQuery(sqlselect); // process results while(rs.next()) { result = ""; id = rs.getInt(1); zip = rs.getInt(3); name = rs.getString(2); result = result.valueOf(id) + " "; result += result.valueOf(zip) + " "; result += name; System.out.println("Values are: " + result); }

23

JDBC Application

//save your actions con.commit();//close connection

con.close(); } catch(Exception e) { System.out.println(e.getMessage()); } }}

24

Sample JDBC ResultsD:\data\cs423_fs00\java\jdbc examples>java sample1bValues are: 1 99141 Some Shirt CompanyValues are: 2 98272 Good Candy CompanyValues are: 3 11455 Penns PensValues are: 4 56899 Close To You MagnetsValues are: 5 98151 Cute CrittersValues are: 6 98565 Seattle SignsValues are: 7 59909 The Artist GroupValues are: 8 89980 YummysValues are: 0 64110 Bobs PCs

Insert row: 1Values are: 1 99141 Some Shirt CompanyValues are: 2 98272 Good Candy CompanyValues are: 3 11455 Penns PensValues are: 4 56899 Close To You MagnetsValues are: 5 98151 Cute CrittersValues are: 6 98565 Seattle SignsValues are: 7 59909 The Artist GroupValues are: 8 89980 YummysValues are: 0 64110 Bobs PCsValues are: 9 97526 Bobs ISP

25

Sample JDBC Results

Deleted row: 1Values are: 1 99141 Some Shirt CompanyValues are: 2 98272 Good Candy CompanyValues are: 3 11455 Penns PensValues are: 4 56899 Close To You MagnetsValues are: 5 98151 Cute CrittersValues are: 6 98565 Seattle SignsValues are: 7 59909 The Artist GroupValues are: 8 89980 YummysValues are: 0 64110 Bobs PCs

D:\data\cs423_fs00\java\jdbc examples>

26

Setting up ODBC in Windows(NT, 2000, XP, Vista, 7(?) )

1.Verify that ODBC Data Sources (ODBC) is loaded in Control Panel / Administrative tools

27

Setting up ODBC in Windows

2.Open Data Source Administrator and add source

28

Setting up ODBC in Windows

3.After selecting database type, add Source name, and select specific database image.

29

Setting up ODBC in Windows

4.Add login Name and password

30

Transaction Support

• Consists of one or more statements that have been executed, completed, and then either committed or rolled back

• Default mode for statements is auto-commit– Each statement becomes a “transaction”

• Can be disabled to support controlled commit or rollback (for multiple statement transactions).– con.setAutoCommit(false);– con.commit();– con.setSavepoint();– con.rollback();

• Transaction support defined in DatabaseMetaData

31

Summary

• JDBC Allows Java programmers to build customized interfaces to standard database management systems through a number of approaches.

• JDBC uses a standardized instruction syntax (SQL) to send queries to databases

• The JDBC-ODBC bridge allows Java to use an existing database connectivity method to gain easy access to existing databases.