如果选中复选框，则在多个表中插入数据

I am creating a user registration form with simple requirements.and insert data with simple query

<?php

if (isset($_POST) && isset($_POST["form_register"]))
{
    $insert_query = "INSERT INTO users SET
                        users.first_name='" . mysql_real_escape_string($_POST['fname']) . "',
                        users.last_name='" . mysql_real_escape_string($_POST['lname']) . "',
                        users.email='" . mysql_real_escape_string($_POST['email']) . "',
                        users.password='" . mysql_real_escape_string($_POST['password']) . "';";

    if (mysql_query($insert_query))
    {
        $_SESSION['messageType'] = "success_msg";
    }
    else
    {
        $_SESSION['message'] = "-Registration not Successful.";
        $_SESSION['messageType'] = "error_msg";
    }
}
?>

but now I have 3 extra fields in this form. If I select a checkbox then the other 2 field data go in another table with having this data also. how can i do that?

It is my old code...now I add 3 new columns, 1 checkbox and 2 text boxes.

The query is, if checkbox is selected then other 2 colums values go in another table and if checkbox is not select then working 1 query.

We really need to see your form as what you're providing us is way too vague, also, check the ending syntax for your $insert_query.

If I comprehended the question right, the final code should look something like this.

Tell me if I'm wrong

<?php 
if(isset($_POST) && isset ($_POST["form_register"])){
    $insert_query1 = "INSERT INTO users SET
        first_name='".mysql_real_escape_string($_POST['fname'])."',
        last_name='".mysql_real_escape_string($_POST['lname'])."',
        email='".mysql_real_escape_string($_POST['email'])."',
        password='".mysql_real_escape_string($_POST['password'])."'";

    if(mysql_query($insert_query)){
        $_SESSION['messageType'] = "success_msg";
    } else {
        $_SESSION['message']  = "-Registration not Successful.";
        $_SESSION['messageType'] = "error_msg";
    }

    if($_POST['checkbox']) {
        $insert_query2 = ""; //Put your second MYSQL Query here
    }

    if(mysql_query($insert_query2)){
        $_SESSION['messageType2'] = "success_msg";
    } else {
        $_SESSION['message2']  = "-Registration not Successful.";
        $_SESSION['messageType2'] = "error_msg";
    }
}
?>

If I understand right you want to insert data in another table IF user check the checkbox.

So you have to use another IF like this:

if (mysql_query($insert_query))
{
    if (/* here your condition for checkbox*/)
    {
        /* here your query for the secund table and the new two values*/
    }

    $_SESSION['messageType'] = "success_msg";
}

Note that is extremely important you run the secund query after the success of the first, cause if the first fails for some reason, secund will not be executed.