java database connectivity,JDBC drivers,Database Connection,Statements,callable Statements,prepared statements,caching database connectivity,scrolling result, controlling transactions,escaping character,mapping database types,mapping data types,update prepared statement

2. JAVA DATABASE CONNECTIVITY
Submitted By:-
V. Priyanka, II-M.Sc.,
M. Lavanya, II-M.Sc.,
S. Suryakala, II-M.Sc.,
(N. S. College of Arts & Science, Theni, TamilNadu.)

3. JAVA DATABASE CONNECTIVITY
JDBC DRIVERS:-
The JDBC driver class handles the connection to the
database.
The java SDK contain only one JDBC driver, a jdbc-odbc
bridge that can communicate with an existing open
database connectivity(ODBC) driver.
Other database need a JDBC driver specific to that
database.

4. The jdbc-odbc bridge accepts Uniform Resource
Location(URLs)starting with jdbc:odbc: and use the next field
in that URL to specify the data source name.
The data source name identifiers the particular database
scheme you wish to access.
There are four type of JDBC drivers:
 Type 1 Drivers
 Type 2 Drivers
 Type 3 Drivers
 Type 4 Drivers

5. Type 1 Driver:-
Type 1 JDBC drivers are the bridge drivers such as the jdbc-
odbc bridge.
These drivers rely on an intermediary such as ODBC to
transfer the SQL calls to the database.
bridge drivers often only one rely on native code.
The jdbc-odbc library native cod is part of the java 2 virtual
machine.

6. Type 2 Drivers:-
Type 2 Drivers use the existing database API to communicate
with the database on the client.
Although Type 2 drivers are faster than Type 1 drivers use
native code and require additional permissions to work in an
applet.
A Type 2 drivers might need client-side database code to
connect over the work.

7. Type 3 drivers:-
Type 3 Drivers calls the database API on the server.
JDBC requests from the client are first proxied to the JDBC
driver on the server to run.
This clients can use type 3 and 4 drivers, as they need to native
code.

8. Type 4 Drivers:-
The highest level of driver reimplements the database network
API in the java language.
Type 4 Drivers can also be used on thin clients, as they also
have no native code.

9. DATABASE CONNECTIONS:-
A database connection can be established with a call to the
drivermanager.getconnection method.
The call takes a URL that identifies the database and optionally,
the database login user name and password.
Connection con=DriverManager.getconnection (url);
Connection con=DriverManager.getconnection (url,
“user”, “password” );
After a connection is established, a statement can be run against
the database. The result of the statement can be retrieved and
the connection is closed.

10. STATEMENTS:-
There are three basic types of SQL statements used in the JDBC
API. They are
Callable Statement
Statement
Prepared Statement

11. CALLABLE STATEMENTS:-
A callable statement is the statement, which lets you execute SQL stored
procedure. Once you have established a connection to a database, you can use
the connection.prepareCall( ) method to create a callable statement.
EX:-
Creates a callable Statement object with three parameters for storing account
login information.
Callable Statement cs=
con . prepareCall (“{call accountlogin(?,?,?)}”);
cs . setString (1, theuser);
cs . setString (2, password);
cs.registerOutParameter(3,Types,DATE);
cs.executeQuerry( );
Date lastLogin=cs . getdate(3);

12. Statements:-
The statement interfere execute a simple SQL statement
with no parameters.
Query Statement:-
This code segment creates a statement object and calls the
Statement . executeQuerry( ) method to select text from the dba
database.
The result of the query are returned in a ResultSet Object. The
required result are then retrieved from a ResultSet Object.

13. Example:-
Statement stmt = con . createStatement();
ResultSet results = stmt.executeQuery(“SELECT
TEXT FROM dba”);

14. Update Statements:-
This code segment creates a Statement object and calls the
Statement . executeUpdate method to add an email address to a
table in the dba database.
String updateString = “INSERT INTO dba
VALUES(SOME TEXT)”;
int count = stmt.executeUpdate(updateString);

15. Prepared Statement:-
The PreparedStatement interface descends from the Statement
interface and uses a template to create a SQL request.
Use a PreparedStatement to send precompiled SQL, statements
with one or more parameters.
Query Prepared Statement:-
This code segment creates a PreparedStatement object to
select user data based on the user’s email address. The question
mark(“?”)indicates that the statement has one parameter.

16. Example:-
PreparedStatement pstmt = con. PreparedStatement(“select
The user from registration where email address like ?”);
// Initialize first parameter with email address//
Pstmt . setString(1,emailAddress);
ResultSet results = ps . executeQuerry();

17. Update Prepared Statement:-
This code segment creates a PreparedStatement object to
update a seller’s registration record. The template has five
parameters.
PreparedStatement pstmt = con. PreparedStatement(“Insert
into registration(theuser, password, email address,
creditcard, balance) values ?,?,?,?,?)”);
Ps.setString(1,theuser);
Ps.setString(2,password);
Ps.setString(3,email address);
Ps.setString(4,credit card);
Ps.setDouble(5,balance);
Ps.setUpdate();

18. Caching Data Base Connectivity:-
The Prepared Statement concept of reusing requests can
be extended for caching the results of a JDBC call.
Results Set:-
The ResultSet interface managers access to data returned from
a query.
The data returned, equals one row in a database table.
Some queries return only one row of data while many queries
return multiple rows of data.

19. Scrolling Result:-
JDBC 2.0 introduced scrollable results sets whose values can
be read and updated if reading and updating is supported by the
underlying database.
one advantage to the new result set is you can update a set of
matching rows without issuing an additional execute Update
call.
The updates are made using JDBC calls and so on custom SQL
commands need be generated.

20. Controlling Transactions:-
JDBC statements are processed in full auto-command mode.
This mode works well for a single database query, but if an
operation depends on several database statements that all have
to completely successfully or the entire operation is cancelled,
a finer transaction is needed.

21. To use transaction management in the JDBC platform, you first
need to disable the full auto-commit mode by calling:
Connection con = getConnection( );
con . setAutoCommit(false);
At this point ,you can either commit any following JDBC
statements or undo any updates by calling the connection.
rollback method.
The rollback call is commonly placed in the Exception
Handler, although it can be placed anywhere in the transaction
flow.

22. Escaping Character:-
The JDBC API provide the escape keywords you can specify the
character you want to escape characters.
EX:-
stmt.executeQuery(“select tax from sales where tax like
‘10%’ (escape ‘’)”);
To solve this problem, the following method escape any ‘symbol
found in the input line’ is used.
This method can be extended to escape any other character such
as commas, that the database or database driven might interpret
another way.

23. Program:
static public String escapeLine (String s)
{
String retvalue = s;
if (s. indexOf (“ ‘ ‘ “); !=-1)
{
StringBuffer hold = new StringBuffer ();
char c;
for(int i=0; I<s.length (); i++)
{
hold.append (“ ‘ ‘ “);
}
else
{
hold.append(c);
}
}
Retvalue=hold.toString( );
}
Return retvalue;}

24. Mapping Data Base Types:-
JDBC type such as Integer that are represented as an Integer in
most popular database.
The JDBC type for a table column does not match the type as it
represented in the database.
This means calls to ResultSet . getObject, preparedStatement .
setobject and callableStatement.getobject()

25. Mapping Date Types
The DATE type is where most mismatches occur. This is
because the java.util.Date class represents both Date and Time but
SQL has the following three types to represent data and time
information.
 A DATE type that represents the date only (03/23/99)
 A TIME type that specifies the time only (12:03:59)
 A TIMESTAMP that represents time value in nanoseconds.
These three additional types are provided in the java.sql
packages as java.sql.Date, java.sql.Time and java.sql.Timestamp and
are all subclasses of java.util.Date.