3104Chapter4_PPT

8/12/2019 3104Chapter4_PPT

1/52

1

AACS 3104

Chapter 4

Java Database Programming

8/12/2019 3104Chapter4_PPT

2/52

2

Objectives

To become familiar with the JDBC API(1.0).

To learn how to load a driver, connectto adatabase, execute statements, and process resultsetsusing JDBC (2.0).

To use the prepared statementsto executeprecompiled SQL statements(3.0).

To process updateableand scrollableresult sets.

(4.0)

8/12/2019 3104Chapter4_PPT

3/52

3

1.0 The Design and use of JBDC

The Java API(Application Programming Interface) for

developing Java Database applications is called JDBC.

JDBC provides Java programmers with a uniform interfacefor accessingand manipulatinga wide range of relationaldatabases.

Using the JDBC API, applications written in Javaprogramming language can execute SQL statements,

retrieve results,

present data in a user friendly interface, and propagates changes back to the database.

8/12/2019 3104Chapter4_PPT

4/52

4

1.0 The Design and use of JBDC (Contd)

The relationship between Java program, JDBC API, JDBC

drivers, and relational database are shown below.

Java Programs

JDBC API

MySQL JDBC

Driver

Microsoft

Access

Database

JDBC-ODBC

Bridge Driver

Oracle JDBC

Driver

MySQL

Database

Oracle

Database

Microsoft ODBCDriver

This chapterwill cover how

to connect to

MS Access

Database Only

8/12/2019 3104Chapter4_PPT

5/52

5


Java Programs

JDBC API

MySQL JDBC

Driver

MicrosoftAccess

Database

JDBC-ODBC

Bridge Driver

Oracle JDBC

Driver

MySQL

Database

Oracle

Database

Microsoft ODBC

Driver

JDBC API is a set of interfaces

and classesused to write Java

programs for accessing andmanipulating relational databases.

JDBC drivers are database-

specific and are normallyprovided by the database

vendors.

8/12/2019 3104Chapter4_PPT

6/52

6


Table below shows the Database driver for different databasevendor.

Database Database Driver

MySQL MySQL JDBC driver (can be downloaded online)

Oracle Oracle JDBC drivers (can be downloaded online)

MsAccess JDBC-ODBC driver ( included in JDK)

ODBC is a technology developed by Microsoft for accessing

databases on the Windows platform

An ODBC driver is preinstalledon Windows.

The JDBC-ODBC bridge driver allows a Java program to access

any ODBC data source.

8/12/2019 3104Chapter4_PPT

7/527

2.0 Connecting to and Querying a Database

2.1 JDBC Appl ic at ion Programm ing Interface (API) Driver

Connect ion

Statements

ResultSet

2.2 Steps in con nect ing and querying a database

Step 1: Loading Driver

Step 2: Establ ishing Connect ion

Step 3: Creat ing and Execut ing Statements

Step 4: Processing ResultSet ob ject

2.3 Example

8/12/2019 3104Chapter4_PPT

8/528

2.1 JDBC Application Programming I nterface (API )

The JDBC API consists of classes and interfaces

for Establishingconnectionswith databases,

Sending SQL statementsto databases,

Processingthe resultsof the SQL statements

and etc.

Four (4) key interfaces are needed to develop anydatabase application using Java:

1. Driver2. Connection

3. Statements

4. ResultSet

8/12/2019 3104Chapter4_PPT

9/529

2.1 JDBC Application Programming I nterface (API )

Driver

Connection Connection

Statement Statement Statement Statement

ResultSet ResultSet ResultSet ResultSet

Creating andexecutingstatements

Establishing

connections

ProcessingResultSet

Load Driver

The relationship of the 4 interfaces is shown in Figure 4.2.

Figure 4.2 Relationships betweenDriver, Connection, Statement

andResultSet.

8/12/2019 3104Chapter4_PPT

10/5210

2.2 Steps in connecting and querying a database

The JDBC interfaces and classes are the building blocks in

the development of Java database programs

A typical Java program takes the following steps to access

the database:

Step 1:

Loading driver

Step 2:

Establish connection

Step 3:Create and Execute statement

Step 4:

Process resultset

8/12/2019 3104Chapter4_PPT

11/5211

An appropriate driver must be loaded using the statement shown below

before connecting a database.The Driver class for MS Access is sun.jdbc.odbc.JdbcOdbcDriver

Statement to load a driver:

Class.forName(");

A driver is a class. For example:

Database Driver Class Source

Access sun.jdbc.odbc.JdbcOdbcDriver Already in JDK

NOTE: The JDBC-ODBC driver for Access is bundled in JDK.

Loading

drivers

Establishing

connections

Creating and

executing

Statements

Processing

ResultSet

put in here

2.2Steps in connecting and querying a database (Contd)

8/12/2019 3104Chapter4_PPT

12/5212

A connection is like a cablethat links your program to a

database.

To connect to a database, use the static method

getConnection(databaseURL) in the DriverManagerclass

Connectionconnection=

DriverManager.getConnection(databaseURL);

Database URL PatternAccess jdbc:odbc:dataSource

See Appendix A in Lecture Note

for creating an ODBC data source

Loading

drivers

Establishing

connections

Creating and

executing

Statements

Processing

ResultSet

put in here


8/12/2019 3104Chapter4_PPT

13/52

13

Loading drivers

Establishingconnections

Creating and

executing

statements

Processing

ResultSet

Example:

Suppose a data source named CustomerDBhas beencreated for a MS Accessdatabase

we create the connection as follows:

ConnectionconCustomer=

DriverManager.getConnection("jdbc:odbc:CustomerDB");


8/12/2019 3104Chapter4_PPT

14/52

14

An object of Statementcan be viewed as a cartthat

deliversSQLstatements for execution by the database and

brings backthe resultback to the program.

Statementstatement= connection.createStatement( );

Where

connectionis Connectionobject created.


Loading drivers


Creating and

executing

statements

Processing

ResultSet

8/12/2019 3104Chapter4_PPT

15/52

15

Once a Statement object is created, we can use it to

execute executing SQL statements.


Loading drivers


Creating and

executing

statements

Processing

ResultSet

SQL Types Statement method used

INSERT, UPDATE

and DELETE

executeUpdate( Stringsql)

SELECT query

NOTE:

query result is stored

in ResultSetobject

executeQuery(Stringsql) : ResultSet

8/12/2019 3104Chapter4_PPT

16/52

16

Lets assume that we have a table called Customerswith

the following fields:Customers(cust_ID, cust_Name, cust_Address)

To INSERT new customer:

StatementstmtInsert= conCustomer.createStatement();

stmtInsert.executeUpdate(INSERT INTO Customers

VALUES(C100, Adam, KL));


Loading drivers


Creating and

executing

statements

Processing

ResultSet

Use executeUpdate() method because we want to

INSERT record

8/12/2019 3104Chapter4_PPT

17/52

17


Loading drivers


Creating and

executing

statements

Processing

ResultSet

Lets assume that we have a table called Customerswith

the following fields:

Customers(cust_ID, cust_Name, cust_Address)

To query (SELECT)customer record

StatementstmtSelect= conCustomer.createStatement();

ResultSetrsCustomer; // declare ResultSet object to store query result

// select all customer recordrsCustomer= stmtSelect.executeQuery(SELECT * FROM

Customers);

//then we can process the result in rsCustomer later, see step 4

8/12/2019 3104Chapter4_PPT

18/52

18

The ResultSetmaintains a table whose current row

can be retrieved.The initialrowpositionis null.

A defaultResultSetobject is NOTupdatableand has a

cursor that moves forward ONLY.


Loading drivers


Creating and

executing

statements

Processing

ResultSet

8/12/2019 3104Chapter4_PPT

19/52

19

Some useful methods in ResultSet:


Methods Description

next() Moves the cursor to the

next row.

Returns false if there are

no more rows in theResultSet object

getXxx( int ColumnIndex) : Xxx Retrieves the value at the

specified column index as

Xxxtype value

getXxx( String columnName) : Xxx Retrieves the value at the

specified column index as

Xxxtype value

Column index in ResultSet starts from 1 (ONE)

Loading drivers


Creating and

executing

statements

Processing

ResultSet

8/12/2019 3104Chapter4_PPT

20/52

20

Example:

rsCustomer.next() // move cursor to next row

// get String value from 1stcolumnin result set and store in a

// String variable

String customerID = rsCustomer.getString(1);

OR

// get String value from Column nameCust_Namein result set

// and store in a String variable

String customerName = rsCustomer.getString(Cust_Name);


Loading drivers


Creating and

executing

statements

Processing

ResultSet

8/12/2019 3104Chapter4_PPT

21/52

21

Lets assume that we have a table called Customerswith the

following fields:

Customers(cust_ID, cust_Name, cust_Address)

To query (SELECT)customer record

StatementstmtSelect= conCustomer.createStatement();

ResultSetrsCustomer; // declare ResultSet object to store query result

// select all customer names

rsCustomer= stmtSelect.executeQuery(SELECT cust_Name FROM

Customers);

// loop through the resultset and display the customer names

while( rsCustomer.next() )

{ // display customer name on the console

System.out.println(name: + rsCustomer.getString(1));

}


Loading drivers


Creating and

executing

statements

Processing

ResultSet

8/12/2019 3104Chapter4_PPT

22/52

22

2.3 Example: connecting and querying MS Access Database

Example 1:

The program in Listing 4.1 connects to an ODBCdata sou rcenamed CustomerDB and makes query

to all customers record.

(See Appendix A [ Page 22in lecture note ] on how to

create ODBC data source)

It then displays all the customer names in the

console.

The Customerstable in CustomerDB is as follows:

Customers( Cust_ID, Cust_Name, Cust_Address )

Run SimpleJDBC view SimpleJDBC codeHOW TO create

ODBC data source
http://localhost/var/www/apps/conversion/tmp/scratch_4/HowToCreateODBCDataSource.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_4/HowToCreateODBCDataSource.pdf

8/12/2019 3104Chapter4_PPT

23/52

8/12/2019 3104Chapter4_PPT

24/52

24

2.3 Example: connecting and querying MS Access Database

Example 3:

Retrieve data from Database and bind them to a Combo Box

// in the constructor in GUI application

Class.forName(sun.jdbc.odbc.JdbcOdbcDriver);

ConnectionconCustomer=

DriverManager.getConnection(jdbc:odbc:CustomerDB);

StatementstmtCustomer= conStudent.createStatement();

ResultSetrsCustomer= stmtCustomer.executeQuery("SELECT Cust_ID FROM

Customers");

while( rsCustomer.next() ){ String custID = rsCustomer.getString(1); // get Cust_ID value

// need to convert String value to Object ,

// this is because the addItem(Object o) method only accept Object type value

jcboCustomerID.addItem( (Object)custID);

}

8/12/2019 3104Chapter4_PPT

25/52

25

3.0 PreparedStatement

The Statementinterface is used to execute static

(fixed) SQL statements that contains NO parameters

In order words, you MUSTalready specifiedthe values

in the condition in the WHEREclause.

However, Java also provides the PreparedStatement,

which extendingStatementand can be used toexecute a precompiledSQL statement with or without

parameters.

8/12/2019 3104Chapter4_PPT

26/52

26

3.0 PreparedStatement (Contd)

Since the SQL statements are precompiled,they are efficientfor repeated executions

8/12/2019 3104Chapter4_PPT

27/52

27


The PreparedStatementobject is created using the

prepareStatement(String sql)method in the Connection

interface.

String sqlSelect = Insert Into Customer (Cust_ID, Cust_Name,

Cust_Address) Values(?, ?, ?);

PreparedStatementpstmt = connection.prepareStatement(sqlSelect);

The INSERT statement has 3 question marks (?) asplaceholdersfor parametersrepresenting values for

Cust_ID, Cust_Name, Cust_Address in a record of the

Customer table.

8/12/2019 3104Chapter4_PPT

28/52

28


PreparedStatementinterface provides methods to setthe

valuesof the parametersin the object of PreparedStatement. In general, the set methods have the following name and

signature:

setX( int parameterIndex, Xvalue);

whereparameterIndexis the index of the parameter in the statement

Xis the type of the parameterFor example:

setString(2 , adam );

// set the 2nd parameter value to a String value adam

8/12/2019 3104Chapter4_PPT

29/52

29


Lets see a more complete example:

The following codes passthe parametersC007, Jeverson ,PJ to the placeholderfor Cust_ID, Cust_Name and

Cust_Address in the PreparedStatementpstmt declared just now.

String sqlSelect= Insert Into Customer (Cust_ID, Cust_Name,Cust_Address) Values(?, ?, ?);

PreparedStatementpstmt=connection.prepareStatement(sqlSelect);

pstmt.setString(1 , C007 );pstmt.setString(2 , Jeverson );Pstmt.setString(3 , PJ );

8/12/2019 3104Chapter4_PPT

30/52

30


After setting the parameters, you can execute the

prepared statement by calling

executeQuery()[ for SELECT statement], OR

executeUpdate()[ for UPDATE, INSERT and DELETE

statement ].

8/12/2019 3104Chapter4_PPT

31/52

31


Example 4: Insert Customer record using

PreparedStatement object

Sample output

Run InsertCustomerPreparedStatement

InsertCustomerPreparedStatement Code

8/12/2019 3104Chapter4_PPT

32/52

32


HOW DOES IT WORK?

From line 812,

the necessary JTextFieldsand JButtonsare declared.

In line 15,

a PreparedStatementobject called pstmtCustomeris declared.

It is declared as data member so that its lifetimeand scope

starts when the program starts and ends when the program

ends.

8/12/2019 3104Chapter4_PPT

33/52

33


Then in the constructor, it does the following:

1. call the initializedDB() method

From line 4965, 1st load the driver, then establishthe

connection.

Then create a Stringobject to store the INSERT SQL statement.

Then create the PreparedStatementobject pstmtCustomerobject by calling the prepareStatement()method from

Connectionobject and pass in the SQL string value.

8/12/2019 3104Chapter4_PPT

34/52

34


Then in the constructor, it does the following:

2. setup GUI components, add them to JFrame

3. addActionListener for the 2 buttons, namely jbtAdd and

jbtClear

in addCustomer method for jbtAdd

get textfieldvalue accordingly

Call setString() method of PreparedStatementobject to set

theparameter values.

Call executeUpdate() method to update the INSERT

statement to database.

8/12/2019 3104Chapter4_PPT

35/52

35

4.0 Scrollable and Updateable ResultSet

The ResultSetused in the preceding examples are

sequentially forward reading.

Sequential forward reading means

the resultset maintainsa cursorpointing to its

current rowof data.

Initiallythe cursor is positioned before the 1st row.

The next() method movesthe cursorforward to the

next row.

There is to move backwardor update

the resultset and have the changes automatically

reflected in the database

NO WAY

8/12/2019 3104Chapter4_PPT

36/52

36

4.0 Scrollable and Updateable ResultSet (Contd)

With JDBC 2, you can scrollthe row both forwardand

backwardand movethe cursor to a desired location.

You can also insert, deleteor updatea row in a result

set and have the changes automaticallyreflectedin

the database.

8/12/2019 3104Chapter4_PPT

37/52

37


To obtain scrollable and updateable result set, you must

first create a statement with an appropriate typeandconcurrency mode.

For a static Statement object, use

Statementstmt = connection.createStatement( int resultType,int resultsetConcurrency);

For a preparedStatement object, use

PreparedStatementpstmt = connection.prepareStatement(

String sql, int resultType, int resultsetConcurrency);

8/12/2019 3104Chapter4_PPT

38/52

8/12/2019 3104Chapter4_PPT

39/52

39


The value of resultsetConcurrencycound be:

resultsetConcurrency Possible values:

ResultSet.CONCUR_READ_ONLY

The result set CAN NOTbe used to update

the database

ResultSet.CONCUR_UPDATABLE

The result set can be used to updatethe

database

Note:

UPDATABLE,

not

UPDATEABLE

8/12/2019 3104Chapter4_PPT

40/52

40


For example, if you want the result set to

be scrollableand updateable, you can

create a statement as follows:

Statementstmt = connection.createStatement(

ResultSet.TYPE_SCROLL_SENSITIVE,

ResultSet.CONCUR_UPDATABLE);

Reminder Again:

UPDATABLE, not

UPDATEABLE

8/12/2019 3104Chapter4_PPT

41/52

41


After that, you can used the executeQuery() method

of the Statementobject to execute an SQL query

that returns a result set, as follows:

ResultSetresultset = stmt.executeQuery(String sqlQuery);

8/12/2019 3104Chapter4_PPT

42/52

42


Then, you can use the various useful method in

ResultSet interface to scroll(move ) around result

or make changesto the resultset and have the

changes automatically reflected in the database

You can:

1. Scroll or move cursor around resultset

2. Retrieve value of a specified field in the current row

3. Delete the current row

4. Insert a new row ( means new record )5. Update a particular row

8/12/2019 3104Chapter4_PPT

43/52

43


TO Scrollor movecursor around result set

Methods Description

first() Move cursor to the 1strow

next() Move cursor to the nextrow

previous() Move cursor to the previousrow

last() Move cursor to the lastrow

absolute(int row) Move cursor to the specifiedrow

Methods in ResultSet:

8/12/2019 3104Chapter4_PPT

44/52

44


TO Retrieve value of a specified field in the current row:

1. getXxx( int columnIndex) : Xxx

Retrieve the Xxx type value of a field specified by

columnIndex. [ field index starts from 1 ]

2. getXxx( String columnName) : Xxx

Retrieve the Xxx type value of a field specified by

columnName.

[ same as field name in the database ]

The type Xxxcould be String, int, doubleand etc..

8/12/2019 3104Chapter4_PPT

45/52

45


TO deletethe current row in the result set

delete() Delete the current row in the result set,

changeswill automatically reflectedin

the database

8/12/2019 3104Chapter4_PPT

46/52

46


TO insert a new row in a resultset:

3 Steps to insert a row:

1. Call the moveToInsertRow() to movethe cursorto a

special rowthat servesas a staging areafor building a row

to be inserted.

2. Then, update the columns using the

updateXxx (int columnIndex, Xxxvalue) method or

updateXxx( String columnName, Xxxvalue) method.

NOTE: Xxx= type of the value, for example: String, int,

double, and etc.

3. Finally, insert the row using the insertRow() method.

8/12/2019 3104Chapter4_PPT

47/52

47


For example, the following code insert a new row

with the new values:

// 1st, move cursor to the insert row ( MUST DO SO)

rsCustomer.moveToInsertRow();

// 2nd, update Cust_ID, Cust_Name & Cust_Address

rsCustomer.updateString(Cust_ID, C009);

rsCustomer.updateString(Cust_Name, Julia);

rsCustomer.updateString(Cust_Address, PJ);

// 3rd, just call the insertRow() method to insert new row

rsCustomer.insertRow();

8/12/2019 3104Chapter4_PPT

48/52

48


TO update a row in the result set

3 Steps to update a row

1. Move the cursor to desire row. You can use the

absolute(introw) method.

2. call the updateXxx() method to write new value

to the field at the current row

3. finally, call the updateRow() method to update

row in the data source

8/12/2019 3104Chapter4_PPT

49/52

49


For example, the code below updates the address of the

3rd row to Taman TBR

// move cursor to the 3rd row

rsCustomer.absolute(3);

// updates the columns

rsCustomer.updateString(Cust_Address, Taman

TBR);

// updates the row in the data source

rsCustomer.updateRow();

8/12/2019 3104Chapter4_PPT

50/52

50


Other useful method in the ResultSet interface:

cancelRowUpdates()

Cancels the updates made to a row

close()

Closes the result set and releases its resources

isFirst() : boolean

To check whether the cursor is at the 1st row in the

result setisLast() : boolean

To check whether the cursor is at the last row in the

result set

8/12/2019 3104Chapter4_PPT

51/52

51


Other useful method in the ResultSet interface:

getRow(): int

Return the current row number.

The 1st row is 1, 2 for 2nd row and so on.

8/12/2019 3104Chapter4_PPT

52/52


Example 5:

Using Scrollable and Updateable Result Set

The program in Listing 4.4 below demonstrates

using scrollable and updateable result set to scrollcustomer record and insert new customer record.

Run ViewCustomer ViewCustomer Code

Documents

3104Chapter4_PPT