How to search in a string saved in MySQL database

Question

I have created a JList by taking inputs from user in jtextField. Then I have saved the jList to Mysql database by converting the JList to String as I want to save the JList item in a single row as single entry.

code for adding user input to jList:

DefaultListModel dlm= new DefaultListModel();
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

        String userInput= jTextField2.getText();
        dlm.addElement(userInput);
        jList1.setModel(dlm);
        jTextField2.setText(null);     

    } 

Code Used for saving the JList into MySQL database as String:

String allitem=null;
    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         

         for(int i = 0;i<jList1.getModel().getSize();i++)
    {
        allitem = (String)jList1.getModel().getElementAt(i)+"::"+allitem;
    }

try
{
    Class.forName("com.mysql.jdbc.Driver");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/ft", "root", "");
    PreparedStatement stmt = conn.prepareStatement("insert into ftt (listname,listitem) values (?,?)");
    stmt.setString(1, jTextField1.getText());
    stmt.setString(2, allitem);
    stmt.execute();
    conn.close();
}catch(
Exception e)
{
    JOptionPane.showMessageDialog(null, e);
    e.printStackTrace();
}
    JOptionPane.showMessageDialog(null, "done"); 

    }                                        

Now in the next page user can view all the Strings (Jlist is saved as String) item in the JList. I wan to disaplay user the details of the JList item selected. I have created a Jtable and want to display the other details of the JList item selected.

Code I have Tried:

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         

        Update_table1();

    }  

private void Update_table1(){

        try{

            Class.forName("com.mysql.jdbc.Driver");
            Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/ft","root","");
            String query="SELECT listname FROM ftt WHERE listitem=?;";
            PreparedStatement prepstmt=conn.prepareStatement(query);  
            String s = (String) jList1.getSelectedValue();
            prepstmt.setString(1,s);
            ResultSet rs=prepstmt.executeQuery(); 
            jTable3.setModel(DbUtils.resultSetToTableModel(rs));

        }catch(Exception e){

            JOptionPane.showMessageDialog(null, e);
        }
    }

But when using this code the Jtable is not showing any value although it is taking the table header name. Please can anyone check I correct in how to search in the String saved in MySQL database. I think the problem is there as other things are working fine.

note: Its not showing any error or exception.

Answer 1

It is not the best way to keep record as the way you are doing as concatenated string. You better use a normalized table and keep all list elements as a record. For your code you are trying to query on a field which contain concatenated information. So you may use "like" keyword instead of "=".

"SELECT listname FROM ftt WHERE listitem like %?%;"