html php mysql secure -

i use php manage html , have problem input date in mysql. input in mysql or update or delete in mysql ok how can make security input data in mysql because if 1 open see html source code browser can see predefined inputs , can change thats in html , after enter wronk inputs in mysql.

this code:

    options value: <select name="extend">             <option value="<?php $_end1;$newdate = date('y-m-d', strtotime($_end. " + 1 month"));echo $newdate;?>">1 month</option> 

now when if open browser , see code can replease 1 month several month , in mysql.

how can secure , or hide in html.

thx

if you're wanting have fields or input can't edited user, such current date form submitted on or along lines of that, need do of on server side (not client side). data submitted client side can (and should treat will) changed.

instead of having form fields preset values, fields hidden, fields disabled, data rendered javascript, or other way think of storing data on client side, things on server side. can use php script this, seeing you're making use of php. when submit form has go sort of server side script, logic there , submit logic database.