Java Database Connectivity : Updating & Deleting Data

Simple steps on how to update or delete data of a table through a GUI applications in NetBeans IDE.

1 First, follow the steps for searching the data through a GUI. This is to make sure that you are able to bring the data in the text-field for further updation or deletion.

Run View for Searching Data

2 Make sure you have made the text-fields as editable. To make them editable, select all the text-fields and right click. Now, select properties and checkmark(if, unchecked) the editable option.

3 Add a new button and rename it as “Update”. Now on the Update button’s actionperformed event

try {

        Class.forName(“com.mysql.jdbc.Driver”);
        Connection con= (Connection)  DriverManager.getConnection(“jdbc:mysql://localhost:3306/database1″,”root”,””);
Statement stmt=con.createStatement();
        String num  = (String) jList1.getSelectedValue();
String no=jTextField1.getText();
        String title=jTextField2.getText();
        String auth=jTextField3.getText();
        String type=jTextField4.getText();
        String pub=jTextField5.getText();
        String qty=jTextField6.getText();
        String amt=jTextField7.getText(); 
String sql1 = “Update library set NO='” + (no)+ “‘, TITLE='” + (title)+ “‘, AUTHOR='” + (auth)+ “‘, TYPE='” + (type)+ “‘, PUB='” + (pub)+ “‘, QTY='” + (qty)+ “‘, AMOUNT='” + (amt)+ “‘ where NO = ‘” + (num) + “‘”;

stmt.executeUpdate(sql1);

}
catch(Exception e) {
JOptionPane.showMessageDialog(this, e.getMessage());
        }

4 To make your program more better you can make the text-fields empty when the user has completed task of updating his table. Also, you can show a Message Box stating that the update was successful.
To do this add the following codes after/below the line – stmt.executeUpdate(sql1);

jTextField1.setText(“”);
jTextField2.setText(“”);
jTextField3.setText(“”);
jTextField4.setText(“”);
jTextField5.setText(“”);
jTextField6.setText(“”);
jTextField7.setText(“”);
JOptionPane.showMessageDialog(null, “Table LIBRARY Updated!”);

Run View for Updating Database

You can see that when a user clicks the update button the text-fields becomes empty and a message pops-ups stating that the table was updated successfully!

5 Now, for deleting a row from a database. Insert one more button and rename it to “Delete”.

6 On Delete button’s actionPerformed event

try {
Class.forName(“com.mysql.jdbc.Driver”);
Connection con= (Connection)  DriverManager.getConnection(“jdbc:mysql://localhost:3306/database1″,”root”,””);
Statement stmt=con.createStatement();
String num  = (String) jList1.getSelectedValue();

String sql2 = “Delete from library where NO = ‘”+(num)+”‘”;

stmt.executeUpdate(sql2);

JOptionPane.showMessageDialog(null, “Row deleted from the database!”);

}

catch(Exception e) {

JOptionPane.showMessageDialog(this, e.getMessage());

}

Run View for Delete

Remember to change the codes in blue according to your database and your GUI.

Please comment, if you are not able to follow.

//watch a video tutorial for java database connectivity on the videos page