AJAX使用从PHP生成的HTML调用的函数更新MYSQL数据库

I have a php page generating and displaying a table. for the last row in the table i want to display an image with an 'onclick' function attached. this will send the username for the selected row to a script that will use AJAX to update a database. The table displays fine but the AJAX is not working. my php to display the image is:I have a php page generating and displaying a t