Multiple Checkbox Update and Delete Query

I want to update tutor table and tutor course table, i have multiple checkbox for tutor course and if a teacher update his course or other info both table should also update.... tutor can increase or decrease course. I'm using following query but its not working for me

$update_content =   mysql_query("UPDATE wp_tutor
    JOIN wp_tutor_courses
    ON wp_tutor.tutor_id=wp_tutor_courses.tutor_id
    SET wp_tutor.tutor_name='$tNameVar',
    wp_tutor.tutor_qualification='$tQualVar',
    wp_tutor.tutor_skype='$tSkyVar',
    wp_tutor.tutor_specialization='$tuSAreaVar',
    wp_tutor.tutor_gender='$tuGenderVar',
    wp_tutor_courses.course_id='$tuCourseVar'
    WHERE tutor_id='$tid'");

<table cellpadding="5" cellspacing="0" border="1">
        <caption>Tutor Table</caption>
        <thead>
                <tr>
                        <th>Tutor ID</th>
                <th>Tutor Name</th>
                <th>Tutor Skype ID</th>
                <th>Tutor Specialization</th>
            </tr>
        </thead>
        <tbody>
                <tr>
                        <td align="center">1</td>
                <td align="center">Kashif</td>
                <td align="center">kashiflatif</td>
                <td align="center">Financial Accounting</td>
            </tr>
            <tr>
                        <td align="center">2</td>
                <td align="center">Ammar</td>
                <td align="center">ammar.90</td>
                <td align="center">Research Methods</td>
            </tr>
            <tr>
                        <td align="center">3</td>
                <td align="center">Bilal</td>
                <td align="center">bilalhaider95</td>
                <td align="center">Islamic Bond & Practices</td>
            </tr>
        </tbody>
    </table>
    <br />
    <br />
    <table cellpadding="5" cellspacing="0" border="1" style="float:left">
        <caption>Tutor Course Table</caption>
        <thead>
                <tr>
                        <th>Tutor Course ID</th>
                <th>Tutor ID</th>
                <th>Course ID</th>
            </tr>
        </thead>
        <tbody>
                <tr>
                        <td align="center">1</td>
                <td align="center">1</td>
                <td align="center">1</td>
            </tr>
            <tr>
                        <td align="center">2</td>
                <td align="center">1</td>
                <td align="center">2</td>
            </tr>
            <tr>
                        <td align="center">3</td>
                <td align="center">1</td>
                <td align="center">3</td>
            </tr>
            <tr>
                        <td align="center">4</td>
                <td align="center">2</td>
                <td align="center">1</td>
            </tr>
            <tr>
                        <td align="center">5</td>
                <td align="center">2</td>
                <td align="center">3</td>
            </tr>
            <tr>
                        <td align="center">6</td>
                <td align="center">3</td>
                <td align="center">1</td>
            </tr>
        </tbody>
    </table>
    <table cellpadding="5" cellspacing="0" border="1" style="float:left; margin-left:20px;">
        <caption>Course Table</caption>
        <thead>
                <tr>
                        <th>Course ID</th>
                <th>Course Name</th>
            </tr>
        </thead>
        <tbody>
                <tr>
                        <td align="center">1</td>
                <td align="center">Certificate</td>
            </tr>
            <tr>
                        <td align="center">2</td>
                <td align="center">Diploma</td>
            </tr>
            <tr>
                        <td align="center">3</td>
                <td align="center">PGD</td>
            </tr>
        </tbody>
    </table>