Java applications cannot directly communicate with a database to submit and retrieve the results of queries.this is because dbms/rdbms can understand only SQL statements and not java language statements .hence you need a mechanism to transalate java statements to SQL statements.

JDBC API uses a driver to address these issues .JDBC API takes care of converting java commands to generic SQL statements .

There are several categories of jdbc drivers provided by different database vendors .They are

1.JDBC-ODBC bridge driver:there are several DBMS/RDBMS, such as MS acess and SQL server that contain the ODBC driver embedded into them.since the ODBC API is written in the Clanguage and makes use of ponters and other constructs that java does not support ,a java program cannot directly communicate with an ODBC driver.The JDBC-ODBC bridge driver transalates the JDBC API to the ODBC API

2.Native API partly java driver: some DBMS/RDBMS,such as DB2and Informix,contail a JDBC driver supplied by the database vendor.JDBC drivers consist of classes that the JDBC API can invoke directly.

3.NATIVE protocal pure java driver/JDBC-net pure java driver: these drivers are used to connect a client application or applet to a database over a TCP/IP connection

4.JDBC DRIVer MANAGER
the functions are to maintain a list of drivers created for different databases and connect a java apllication to the appropriate driver specified in a java program

5.JDBC-ODBC Bridge
as apart of JDbc ,sun microsysyems provides a driver to acess ODBC data sources from JDBC.This driver s called JDBC-ODBC bridge.

Sowmya

What are the main differences of available four drivers?

The differences among 4 types of drivers are as given below:-

Type 1: JDBC-ODBC Bridge
The type 1 driver, JDBC-ODBC Bridge, translates all JDBC calls into ODBC (Open DataBase Connectivity) calls and sends them to the ODBC driver. As such, the ODBC driver, as well as, in many cases, the client database code, must be present on the client machine.

Type 2: Native-API/partly Java driver
JDBC driver type 2 -- the native-API/partly Java driver -- converts JDBC calls into database-specific calls for databases such as SQL Server, Informix, Oracle, or Sybase. The type 2 driver communicates directly with the database server; therefore it requires that some binary code be present on the client machine.

Type 3: Net-protocol/all-Java driver
JDBC driver type 3 -- the net-protocol/all-Java driver -- follows a three-tiered approach whereby the JDBC database requests are passed through the network to the middle-tier server. The middle-tier server then translates the request (directly or indirectly) to the database-specific native-connectivity interface to further the request to the database server. If the middle-tier server is written in Java, it can use a type 1 or type 2 JDBC driver to do this.

Type 4 Pure Java Driver
Type 4 JDBC drivers are direct-to-database pure Java drivers ("thin" drivers). A Type 4 driver takes JDBC calls and translates them into the network protocol (proprietary protocol) used directly by the DBMS. Thus, client machines or application servers can make direct calls to the DBMS server. Each DBMS requires its own Type 4 driver; therefore, there are more drivers to manage in a heterogeneous computing environment, but this is outweighed by the fact that Type 4 drivers provide faster performance and direct access to DBMS features.

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