} Opening The Connection Our next step is to connect to the database that will process the user s query, as shown in Listing 4.6. Listing 4.6 Opening a database connection. if (evt.target == ConnectBtn) { // If the user clicks the “Connect” button, connect to the database // specified in the DBurl TextArea and the user name specified in the // NameField TextArea. url=DBurl.getText(); Name=NameField.getText(); try { new imaginary.sql.iMsqlDriver(); // This creates a new instance of the Driver we want to use. There are a // number of ways to specify which driver you want to use, and there is // even a way to let the JDBC DriverManager choose which driver it thinks // it needs to connect to the data source. con = DriverManager.getConnection(url, Name, “”); // Actually make the connection. Use the entered URL and the entered // user name when making the connection. We haven’t specified a password, // so just send nothing (”"). ConnectBtn.setLabel(”Reconnect to Database”); // Finally, change what the ConnectBtn to show “Reconnect to Database”. } catch( Exception e ) { e.printStackTrace(); OutputField.setText(e.getMessage()); } // The creation of the connection throws an exception if there was a // problem connecting using the specified parameters. We have to enclose // the getConnection method in a try-catch block to catch any // exceptions that may be thrown. If there is a problem and an exception // thrown, print it out to the console, and to the OutputField. return true; } return false; } // handleEvent() end No Guts, No Glory: Executing Queries And Processing Results Now that we have opened the connection to the data source (Listing 4.6), it s time to set up the mechanism for executing queries and getting the results, as shown in Listings 4.7 and 4.8. The parameter that we need in this method is a String containing the SQL query the user entered into the QueryField. We will return the results of the query as a string
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