Java jdbc

JAVA
JDBC
Prepared by
Miss. Arati A. Gadgil

JDBC
Java JDBC is a java API to connect and execute query with the
database. JDBC API uses jdbc drivers to connect with the database.

API
API (Application programming interface) is a document that
contains description of all the features of a product or software. It
represents classes and interfaces that software programs can follow
to communicate with each other. An API can be created for
applications, libraries, operating systems, etc

JDBCDriver
JDBC Driver is a software component that enables java application to
interact with the database. There are 4 types of JDBC drivers
1.JDBC-ODBC bridge driver
2.Native-API driver (partially java driver)
3.Network Protocol driver (fully java driver)
4.Thin driver (fully java driver)

JDBC-ODBC bridge driver
The JDBC-ODBC bridge driver uses ODBC driver to connect to the
database. The JDBC-ODBC bridge driver converts JDBC method calls
into the ODBC function calls.

connect to the database
Steps
1. Register the driver class
2. Creating connection
3. Creating statement
4. Executing queries
5. Closing connection

1) Register the driver class
public static void forName(String className)throws
ClassNotFoundException
Example
Class.forName("oracle.jdbc.driver.OracleDriver");

2)Create the connection object
1) public static Connection getConnection(String url)throws
SQLException
2) public static Connection getConnection(String url,String name,String
password) throws SQLException
Example
Connection con=DriverManager.getConnection(
"jdbc:oracle:thin:@localhost:1521:xe","system","password");

3) Create the Statement object
The createStatement() method of Connection interface is used to create
statement.
The object of statement is responsible to execute queries with the
database.
public Statement createStatement()throws SQLException
Example
Statement stmt=con.createStatement();

4) Execute the query
The executeQuery() method of Statement interface is used to execute
queries to the database.
This method returns the object of ResultSet that can be used to get all
the records of a table.
public ResultSet executeQuery(String sql)throws SQLException
Example
ResultSet rs=stmt.executeQuery("select * from emp");
while(rs.next())
{
System.out.println(rs.getInt(1)+" "+rs.getString(2));
}

5) Close the connection object
By closing connection object statement and ResultSet will be closed
automatically.
The close() method of Connection interface is used to close the
connection.
public void close()throws SQLException
Example
con.close();

DatabaseMetaData Interface
DatabaseMetaData interface provides methods to get meta data of a
database such as database product name, database product version,
driver name, name of total number of tables, name of total number of
views etc.

Methods
public String getDriverName()throws SQLException
it returns the name of the JDBC driver.
public String getDriverVersion()throws SQLException
it returns the version number of the JDBC driver.
public String getUserName()throws SQLException
it returns the username of the database.
public String getDatabaseProductName()throws SQLException
it returns the product name of the database.
public String getDatabaseProductVersion()throws SQLException
it returns the product version of the database.
public ResultSet getTables(String catalog, String schemaPattern,
String tableNamePattern, String[] types)throws SQLException
it returns the description of the tables of the specified catalog. The
table type can be TABLE, VIEW, ALIAS, SYSTEM TABLE,
SYNONYM etc.

Transaction
Transaction represents a single unit of work
Properties
Atomicity means either all successful or none.
Consistency ensures bringing the database from one consistent state to
another consistent state.
Isolation ensures that transaction is isolated from other transaction.
Durability means once a transaction has been committed, it will remain
so, even in the event of errors, power loss etc.

Connectioninterface
In JDBC, Connection interface provides methods to manage
transaction.
Methods
void setAutoCommit(boolean status)
It is true bydefault means each transaction is committed by
default.
void commit()
commits the transaction.
void rollback()
cancels the transaction.

What is JDBC?
JDBC stands for Java Database Connectivity, which is a standard Java
API for database-independent connectivity between the Java prog
ramming language and a wide range of databases.
Common JDBC Components
DriverManager: This class manages a list of database drivers.
Driver: This interface handles the communications with the database
server.
Connec tion: This interface with all methods for contacting a database.
Statement: You use objects created from this interface to submit the
SQL statements to the database.
ResultSet: These objects hold data retrieved from a database after you
execute an SQL query using Statement objects. It acts as an iterator to
allow you to move throug h its data.
SQLException: T his class handles any errors that occur in a database
application.

JDBC-SQLSYNTAX
Structured Query Language (SQL) is a standardized language that allows
you to perform operations on a database, such as creating entries, reading
content, updating content, and deleting entries.
Create Database:
The CREAT E DATABASE statement is used for creating a new
database. The syntax is:
SQL> CREATE DATABASE DATABASE_NAME;
Example
The following SQL statement creates a Database named EMP:
SQL> CREATE DATABASE EMP;
Drop Database:
The DROP DATABASE statement is used for deleting an existing
database. The syntax is:
SQL> DROP DATABASE DATABASE_NAME;

Create Table:
The CREAT E TABLE statement is used for creating a new table. The
syntax is:
SQL> CREATE TABLE table_name
(
column_name column_data_type,
...
);
Example:
The following SQL statement creates a table named Employees with four
columns:
SQL> CREATE TABLE Employees
( id INT NOT NULL,
age INT NOT NULL,
first VARCHAR(255),
last VARCHAR(255),
PRIMARY KEY ( id )
);

INSERT Data:
The syntax for INSERT looks similar to the following , where column1,
column2, and so on represent the new data to appear in the respective
columns:
SQL> INSERT INTO table_name VALUES (column1, column2, ...);
Example:
The following SQL INSERT statement inserts a new row in the
Employees database created earlier:
SQL> INSERT INTO Employees VALUES (100, 18, 'Zara', 'Ali');

SELECT Data:
The SELECT statement is used to retrieve data from a database. The
syntax for SELECT is:
SQL> SELECT column_name, column_name, ...
FROM table_name
WHERE conditions;
The WHERE clause can use the comparison operators such as =, !=, <,
>, <=,and >=, as well as the BETWEEN
and LIKE operators.
Example
The following SQL statement selects the ag e, first and last columns
from the Employees table where id column is
100:
SQL> SELECT first, last, age
FROM Employees
WHERE id = 100;

The following SQL statement selects the age, first and last columns from
the Employees table where first column contains Zara
FROM Employees
WHERE first LIKE '%Zara%';
the Employees table where first column contains “a” at end
FROM Employees
WHERE first LIKE '%a';
the Employees table where first column contains a at start
FROM Employees
WHERE first LIKE 'a%';

UPDATE Data:
The UPDAT E statement is used to update data. The syntax for
UPDATE is:
SQL> UPDATE table_name
SET column_name = value, column_name = value, ...
WHERE conditions;
and LIKE operators.
Example:
T he following SQL UPDAT E statement changes the age column of the
employee whose id is 100:
SQL> UPDATE Employees SET age=20 WHERE id=100;

DELETE Data:
The DELETE statement is used to delete data from tables. The syntax for
DELETE is:
SQL> DELETE FROM table_name WHERE conditions;
and LIKE operators.
Example:
T he following SQL DELET E statement delete the record of the
employee whose id is 100:
SQL> DELETE FROM Employees WHERE id=100;

ImportJDBCPackages
import java.sql.* ; // for standard JDBC programs
import java.math.* ; // for BigDecimal and BigInteger support
Register JDBC Driver
try
{
Class.forName("oracle.jdbc.driver.OracleDriver");
}
catch(ClassNotFoundException ex)
{
System.out.println("Error: unable to load driver class!");
System.exit(1);
}

Create Connection Object:
Using a database URL with a username and password:
String URL = "jdbc:oracle:thin:@amrood:1521:EMP";
String USER = "username";
String PASS = "password"
Connection conn = DriverManager.getConnection(URL, USER, PASS);
Closing JDBC connections:
conn.close();

Statement
Use for general-purpose access to your database. Useful when you are
using static SQL statements at runtime. T he Statement interface cannot
accept parameters.
PreparedStatement :
Use when you plan to use the SQL statements many times. The
PreparedStatement interface accepts input parameters at runtime.
CallableStatement :
Use when you want to access database stored procedures. The
CallableStatement interface can also accept runtime input parameters.

Creating Statement Object
Before you can use a Statement object to execute a SQL statement, you
need to create one using the Connection
object's createStatement( ) method, as in the following example:
Statement stmt = null;
try
{
stmt = conn.createStatement( );
. . .
} catch (SQLException e)
{
. . .
}
finally {
. . .
}

Once you've created a Statement object, you can then use it to execute a
SQL statement with one of its three execute methods.
boolean execute(String SQL) : Returns a boolean value of true if a
ResultSet object can be retrieved; otherwise, it returns false. Use this
method to execute SQL DDL statements or when you need to use truly
dynamic SQL.
int executeUpdate(String SQL) : Returns the numbers of rows affected
by the execution of the SQL statement. Use this method to execute SQL
statements for which you expect to get a number of rows affected - for
example, an INSERT , UPDAT E, or DELET E statement.
ResultSet executeQuery(String SQL) : Returns a ResultSet object. Use
this method when you expect to get a result set, as you would with a
SELECT statement.

31
Rowsets
Rowsets are the central objects that enable OLE DB components to
expose and manipulate data in tabular form. A rowset object is a set of
rows in which each row has columns of data.
Query processors present query results in the form of rowsets.

32
ResultSet
The SQL statements that read data from a database query, return the data
in a result set. The SELECT statement is the standard way to select rows
from a database and view them in a result set.
The java.sql.ResultSet interface represents the result set of a database
query.
A ResultSet object maintains a cursor that points to the current row in
the result set. The term "result set" refers to the row and column data
contained in a ResultSet object.
The ResultSet interface contains many methods for getting the data of
the current row.

33
public int getInt(String columnName) throws SQLException
Returns the int in the current row in the column named
columnName
public int getInt(int columnIndex) throws SQLException
Returns the int in the current row in the specified column index.
The column index starts at 1, meaning the first column of a row is
1, the second column of a row is 2, and so on.
Similarly, there are get methods in the ResultSet interface for each of the
eight Java primitive types, as well as common types such as
java.lang.String, java.lang.Object, and java.net.URL

Java jdbc

Recommended

More Related Content

What's hot (20)

Viewers also liked (18)

Similar to Java jdbc (20)

More from Arati Gadgil (16)

Recently uploaded (20)

Java jdbc