更改

if (rs.next())

到

while (rs.next())

不仅可以运行一次代码块，而且还可以运行到ResultSet的末尾.

to run to the code block not just once, but till the end of the ResultSet.

它实际上应该看起来像这样

It should actually look like this

DefaultTableModel model = (DefaultTableModel) tblMenu.getModel();
while (rs.next()) {
    String menu_id = rs.getString("menu_id");
    String menu_type = rs.getString("menu_type");
    String menu_cat = rs.getString("menu_cat");
    String menu_name = rs.getString("menu_name");
    String menu_price = rs.getString("menu_price");

    model.addRow(new Object[]{menu_id, menu_type, menu_cat, menu_name, menu_price});
}