Java Interview Questions 53

261. What are drivers available?- a) JDBC-ODBC Bridge driver b) Native API
Partly-Java driver c) JDBC-Net Pure Java driver d) Native-Protocol Pure Java driver

262. 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.

263. 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.

264. What are the steps involved for making a connection with a database or how do you connect to a database?a) 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”);

265. 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).