Original URL: http://www.theregister.co.uk/2006/12/21/access_odbc_jdbc/

Escape from Access DB

The relational database that polarises programmers

By Dr Pan Pantziarka

Posted in Applications, 21st December 2006 11:02 GMT

Do you like Microsoft Access? Well, thanks to an intuitive and powerful user interface and being bundled as part of Office, it has established a niche for itself in many organisations, sometimes unofficially.

The combination of recordable macros, wizard-generated reports, query-by-example and, crucially, the provision of program support using Visual Basic for Applications has made MS Access the tool of choice for legions of developers of varying levels of ability and technical proficiency.

Not only has this led to a proliferation of applications, it has also produced a proliferation of "rescue" projects as those applications have grown in scope, size and complexity. For enterprise developers using Java this data need not remain out of reach thanks to the wonders of JDBC-ODBC bridges.

ODBC (Open Database Connectivity) is an API that provides programmatic access to data using SQL. ODBC adopts a layered approach; an application written to ODBC can talk to any underlying data source that has an ODBC driver. In the case of Access, ODBC support has been there almost from the beginning. In the Java world, a similar architecture exists called JDBC (Java Database Connectivity) in which Java applications written to the API can talk to any data source that has a JDBC driver. Put these together in the form of a JDBC-ODBC bridge and you have a platform-independent mechanism for Java to talk to any DBMS that has JDBC or ODBC drivers.

In the case of Access, the first step to opening the database to ODBC is to create an ODBC Data Source Name for your database. The simplest method is to load the Data Source Administrator from within the Windows Administrator tools (via the Control Panel if you're not running a server version of Windows).

A User DSN creates and registers a DSN for a single user, a System DSN is accessible to all users and a File DSN stores the DSN information to a file which can be shared among different users. In each case the DSN associates a user-defined label with a database driver (Microsoft Access Driver *.mdb) and a specific instance of the database. Once you create the DSN, any program that uses the ODBC API to talk to the underlying database can use it.

In the case of Java, the normal method for talking to a database is to use JDBC. First, the database driver is registered and then a specific database URL is used to establish a connection which can be used to create the statement object. Once this has been done, it's possible to interact with the database using SQL, stored procedures etc.

In the following code snippet, we are going to connect to an Access database which has a DSN of MyAccessDB using Sun's JDBC-ODBC bridge driver

import java.sql.*;

public class AccessDAO {

        private Connection con;
        private Statement st;
private static final String url="jdbc:odbc:MyAccessDB"; 
        private static final String className="sun.jdbc.odbc.JdbcOdbcDriver"; 
        private static final String user=""; 
        private static final String pass=""; 

        AccessDAO()throws Exception { 


        Class.forName(className); 
                con = DriverManager.getConnection(url, user, pass); 
                st = con.createStatement();  

                //do whatever database processing is required 
        } 
} 

It's not just the user data that can be queried using the JDBC-ODBC bridge, the database metadata can also be accessed. The following program will report all of the SQL data types supported by the version of Access used by the database contained in the MyAccessDB DSN:

import java.sql.*; 

public class AccessDAO { 

        private Connection con; 
        private Statement st; 
        private static final String url="jdbc:odbc:MyAccessDB"; 
        private static final String className="sun.jdbc.odbc.JdbcOdbcDriver"; 
        private static final String user=""; 
        private static final String pass=""; 
                
        public AccessDAO()throws Exception { 

                Class.forName(className); 
                con = DriverManager.getConnection(url, user, pass); 
                DatabaseMetaData dbMetaData  = con.getMetaData(); 
                ResultSet dbTypes = dbMetaData.getTypeInfo(); 
                String typeName; 
                System.out.println("Supported Database Types:"); 
                while (dbTypes.next()){ 
                        typeName = dbTypes.getString("TYPE_NAME"); 
                        System.out.println(typeName); 
                } 
                
        } 
        
        public static void main(String[] args) throws Exception{ 
                new AccessDAO(); 
        } 
        
} 

Of course, it's not just Access that supports ODBC. There are many other databases which support the ODBC API, and these aren't limited to the Windows operating system either. Furthermore, ODBC can be used with Excel and represents an alternative to the use of Apache POI or JExcelAPI as methods for interfacing Java and Excel. ®