小编Haf*_*rul的帖子

当用户在删除字段中输入错误的ID时,我想要弹出一个错误.但即使输入了错误的ID,查询仍会继续,但不会删除任何数据.这是我的代码:

String value = jTextField19.getText();

if (value == null || "".equals(value)) {
    JOptionPane.showMessageDialog(null, "The field is blank!");
} else {
    theQuery("DELETE FROM inventorydb WHERE item_id=('"+jTextField19.getText()+"') AND item_id IS NOT NULL");
}

该theQuery方法:

private void theQuery(String query) {
    Connection con = null;
    Statement st = null;
    try {
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/inventory", "root", "");
        st = con.createStatement();
        st.executeUpdate(query);
        JOptionPane.showMessageDialog(null, "Done!");
    } catch (Exception ex) { 
        JOptionPane.showMessageDialog(null,"Error!");
    } 
}