What are available drivers in JDBC?

JDBC is a set of Java API for executing SQL statements. This API consists of a set of classes and interfaces to enable programs to write pure Java Database applications.

JDBC technology drivers fit into one of four categories:

A JDBC-ODBC bridgeprovides JDBC API access via one or more ODBC drivers. Note that some ODBC native code and in many cases native database client code must be loaded on each client machine that uses this type of driver. Hence, this kind of driver is generally most appropriate when automatic installation and downloading of a Java technology application is not important. For information on the JDBC-ODBC bridge driver provided by Sun, see “http://java.sun.com/j2se/1.3/docs/guide/jdbc/getstart/bridge.doc.html#996747” JDBC-ODBC Bridge Driver.
A native-API partly Java technology-enabled driverconverts JDBC calls into calls on the client API for Oracle, Sybase, Informix, DB2, or other DBMS. Note that, like the bridge driver, this style of driver requires that some binary code be loaded on each client machine.
A net-protocol fully Java technology-enabled drivertranslates JDBC API calls into a DBMS-independent net protocol which is then translated to a DBMS protocol by a server. This net server middleware is able to connect all of its Java technology-based clients to many different databases. The specific protocol used depends on the vendor. In general, this is the most flexible JDBC API alternative. It is likely that all vendors of this solution will provide products suitable for Intranet use. In order for these products to also support Internet access they must handle the additional requirements for security, access through firewalls, etc., that the Web imposes. Several vendors are adding JDBC technology-based drivers to their existing database middleware products.
A native-protocol fully Java technology-enabled driverconverts JDBC technology calls into the network protocol used by DBMSs directly. This allows a direct call from the client machine to the DBMS server and is a practical solution for Intranet access. Since many of these protocols are proprietary the database vendors themselves will be the primary source for this style of driver. Several database vendors have these in progress.

a) JDBC-ODBC Bridge driver

b) Native API Partly-Java driver

c) JDBC-Net Pure Java driver

d) Native-Protocol Pure Java driver

Can you write code to sort the following string values naturally (i.e. in alphabetical order)? (JEE, Java, Servlets, JMS, JNDI, JDBC, JSP, and EJB)

Here is the sample code that makes use of the default compareTo( ) provided in the String class as it implements the Comparable interface and the Collections utility class that provides a sorting method, which internally uses the efficient “merge sort” algorithm.

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

public class Sort1 {

public static void main(String[] args) {

List<string> values = Arrays.asList(“JEE”, “Java”, “Servlets”, “JMS”, “JNDI”, “JDBC”, “JSP”, “EJB”);

Collections.sort(values); // uses the default compareTo(String anotherString) in the String class

System.out.println(values);

}

Output:

[EJB, JDBC, JEE, JMS, JNDI, JSP, Java, Servlets]

Is there anything wrong with the above code?

Yes, 2 things — firstly, the above sort is case sensitive, that is the uppercase takes priority over lowercase pushing ‘Java’ after ‘JSP’. Secondly, if the collection had any null values, it will throw a NullpointerException.

These two issues can be rectified by providing a custom sorting implementation that ignores case and handles null values by pushing them to the end. The Collections class’s sort method takes a Comparator implementation as a second argument. In the code below, the Comparator has been implemented as an anonymous inner class. The compare(…) method will be called a number of times by the Collections.sort(list, comparator).

import java.util.Arrays;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

public class Sort2 {

public static void main(String[] args) {

List<String> values = Arrays.asList(“JEE”, “Java”, null, “Servlets”, null, “JMS”, “JNDI”, “JDBC”, “JSP”, null,”EJB”);

//The comparator is defined as an anonymous inner class, but it can be

//defined in its own class. Handles nulls and ignores case

Collections.sort(values, new Comparator<String>() {

@Override

public int compare(String o1, String o2) {

//push the null values to the end

if(o1 == null){

if(o2 == null) {

return 0;

}

return 1;

}

else if(o2 == null){

return -1;

}

return o1.compareToIgnoreCase(o2);

}

}); // anonymous inner class end

System.out.println(values);

}

What is the difference between JDBC and ODBC

a) OBDC is for Microsoft and JDBC is for Java applications. b) ODBC can’t be directly used with Java because it uses a C interface. c) ODBC makes use of pointers which have been removed totally from Java. d) ODBC mixes simple and advanced features together and has complex options for simple queries. But JDBC is designed to keep things simple while allowing advanced capabilities when required. e) ODBC requires manual installation of the ODBC driver manager and driver on all client machines. JDBC drivers are written in Java and JDBC code is automatically installable, secure, and portable on all platforms. f) JDBC API is a natural Java interface and is built on ODBC. JDBC retains some of the basic features of ODBC.

What are the types of JDBC Driver Models and explain them

There are two types of JDBC Driver Models and they are: a) Two tier model and b) Three tier model Two tier model: In this model, Java applications interact directly with the database. A JDBC driver is required to communicate with the particular database management system that is being accessed. SQL statements are sent to the database and the results are given to user. This model is referred to as client/server configuration where user is the client and the machine that has the database is called as the server. Three tier model: A middle tier is introduced in this model. The functions of this model are: a) Collection of SQL statements from the client and handing it over to the database, b) Receiving results from database to the client and c) Maintaining control over accessing and updating of the above.

What are the steps involved for making a connection with a database or how do you connect to a database

Loading the driver : To load the driver, Class. forName() method is used. Class. forName(”sun. jdbc. odbc. JdbcOdbcDriver”); When the driver is loaded, it registers itself with the java. sql. DriverManager class as an available database driver. b) Making a connection with database: To open a connection to a given database, DriverManager. getConnection() method is used. Connection con = DriverManager. getConnection (”jdbc:odbc:somedb”, “user”, “password”); c) Executing SQL statements : To execute a SQL query, java. sql. statements class is used. createStatement() method of Connection to obtain a new Statement object. Statement stmt = con. createStatement(); A query that returns data can be executed using the executeQuery() method of Statement. This method executes the statement and returns a java. sql. ResultSet that encapsulates the retrieved data: ResultSet rs = stmt. executeQuery(”SELECT * FROM some table”); d) Process the results : ResultSet returns one row at a time. Next() method of ResultSet object can be called to move to the next row. The getString() and getObject() methods are used for retrieving column values: while(rs. next()) { String event = rs. getString(”event”); Object count = (Integer) rs. getObject(”count”);

Why there are two Date classes; one in java.util package and another in java.sql?

A thin wrapper around a millisecond value that allows JDBC to identify this as an SQL DATE value. A milliseconds value represents the number of milliseconds that have passed since January 1, 1970 00:00:00.000 GMT. To conform with the definition of SQL DATE, the millisecond values wrapped inside a java.sql.Date instance must be ‘normalized’ by setting the hours, minutes, seconds, and milliseconds to zero.

Explanation: A java.util.Date represents date and time of day, a java.sql.Date only represents a date (the complement of java.sql.Date is java.sql.Time, which only represents a time of day, but also extends java.util.Date).

What is JDBC

JDBC is a set of Java API for executing SQL statements. This API consists of a set of classes and interfaces to enable programs to write pure Java Database applications.

What type of driver did you use in project?-

JDBC-ODBC Bridge driver (is a driver that uses native(C language) libraries and makes calls to an existing ODBC driver to access a database engine).

How do you pass data (including JavaBeans) to a JSP from a servlet?-

?– (1) Request Lifetime: Using this technique to pass beans, a request dispatcher (using either “include” or forward”) can be called. This bean will disappear after processing this request has been completed. Servlet: request. setAttribute(”theBean”, myBean); RequestDispatcher rd = getServletContext(). getRequestDispatcher(”thepage. jsp”); rd. forward(request, response); JSP PAGE:<jsp: useBean id=”theBean” scope=”request” class=”. . . . . ” />(2) Session Lifetime: Using this technique to pass beans that are relevant to a particular session (such as in individual user login) over a number of requests. This bean will disappear when the session is invalidated or it times out, or when you remove it. Servlet: HttpSession session = request. getSession(true); session. putValue(”theBean”, myBean); /* You can do a request dispatcher here, or just let the bean be visible on the next request */ JSP Page:<jsp:useBean id=”theBean” scope=”session” class=”. . . ” /> 3) Application Lifetime: Using this technique to pass beans that are relevant to all servlets and JSP pages in a particular app, for all users. For example, I use this to make a JDBC connection pool object available to the various servlets and JSP pages in my apps. This bean will disappear when the servlet engine is shut down, or when you remove it. Servlet: GetServletContext(). setAttribute(”theBean”, myBean); JSP PAGE:<jsp:useBean id=”theBean” scope=”application” class=”. . . ” />