Understanding Connection Object
A Connection object represents a connection with a database. When we connect to a database by using connection method, we create a Connection Object, which represents the connection to the database. An application may have one or more than one connections with a single database or many connections with the different databases also.
We can use the Connection object for the following things:
1). It creates the Statement, PreparedStatement and CallableStatement objects for executing the SQL statements.
2). It helps us to Commit or roll back a jdbc transactionn.
3). If you want to know about the database or data source to which you are connected then the Connection object gathers information about the database or data source by the use of DatabaseMetaData.
4). It helps us to close the data source. The Connection.isClosed() method returns true only if the Connection.close() has been called. This method is used to close all the connection.
Firstly we need to to establish the connection with the database. This is done by using the method DriverManager.getConnection(). This method takes a string containing a URL. The DriverManager class, attempts to locate a driver that can connect to the database represented by the string URL. Whenever the getConnection() method is called the DriverManager class checks the list of all registered Driver classes that can connect to the database specified in the URL.
String url = "jdbc: odbc: makeConnection";
Connection con = DriverManager.getConnection(url, "userID", "password");