How to add new column to MYSQL table?

I am trying to add a new column to my MYSQL table using PHP. I am unsure how to alter my table so that the new column is created. In my assessment table I have:

assessmentid | q1 | q2 | q3 | q4 | q5 

Say I have a page with a textbox and I type q6 in to the textbox and press a button then the table is updated to:

assessmentid | q1 | q2 | q3 | q4 | q5 | q6

My code:

<?php 
  mysql_query("ALTER TABLE `assessment` ADD newq INT(1) NOT NULL AFTER `q10`");
?>
  <form method="post" action="">
    <input type="text" name="newq" size="20">
    <input type="submit" name="submit" value="Submit">

your table:

q1 | q2 | q3 | q4 | q5

you can also do

ALTER TABLE yourtable ADD q6 VARCHAR( 255 ) after q5

 $table  = 'your table name';
 $column = 'q6'
 $add = mysql_query("ALTER TABLE $table ADD $column VARCHAR( 255 ) NOT NULL");

you can change VARCHAR( 255 ) NOT NULL into what ever datatype you want.