SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy");
            Date date = sdf.parse(d);
            Calendar cal = GregorianCalendar.getInstance();

            for (i=0;x>i;i++){

            cal.add(GregorianCalendar.DATE, 7);
            String t = sdf.format(cal.getTime());
            DefaultTableModel model = (DefaultTableModel) jTable1.getModel();
            model.addRow(new Object[]{t,c});

it boils down to this:

step 1a: learn to read data from a JTable (which is not an array, just so you know)
step 1b: write the code that does so

step 2a: learn to write data into a DB
step 2b: write the code that does so

step 3: combine the code from 1b and 2b

In addition to what stultuske has said, you can use t and c directly because they are the content of the JTable row.