How to delete a saved row in mysql database after clicking on a 'exit' button

Question

I currently have an upload button that saves all types of files to a MySQL table. I have an exit button that I want to delete the currently uploaded files if clicked. NOTE: all files uploaded on current page has same referenceID so the query is as easy as saying delete all from table where id=id..

Here is the button:

<button type="submit" name="submit" value="exit" style="float:left;
   class="buttonLW" href="https://BACK-LINK">exit
</button>

Here is the PHP delete query (psuedo code):

if ($submitButton === "delete-new") { 

    $query15 ="DELETE * FROM table WHERE id='{$id}'";

}

my question, is the button allowed to use this sort of format? am I allowed to say if ($submitButton === "delete-new") without using a form?

How can I go about deleting the currently saved files with same id after clicking my exit button.

Sidenote: ID's must be unique, as opposed to a class where elements can each contain the same. — Funk Forty Niner
– Funk Forty Niner, Commented Jun 9, 2014 at 14:59
all ids are unique, I have 1 table for uploads that corresponds to the main table which is connected through its id. — Michael
– Michael, Commented Jun 9, 2014 at 15:02
so you can have 1 report with a unique id, but many uploads with that correspond to that id — Michael
– Michael, Commented Jun 9, 2014 at 15:03
"NOTE: all files uploaded on current page has same ID" why is that? — Funk Forty Niner
– Funk Forty Niner, Commented Jun 9, 2014 at 15:04
yes, the uploads do indeed have same id, but its more of a referenceid — Michael
– Michael, Commented Jun 9, 2014 at 15:05

Community · Accepted Answer · 2023-11-17 19:30:35Z

0

Upfront, the style value isn't terminated, you're missing the closing quote ".

If you get $submitButton with

$submitButton = $_POST['submit'];

you can compare it that way, but the value will be exit and not delete-new. So you must rather say

if ($submitButton === 'exit') {
    // ...
}

or change value="exit" to value="delete-new".

Which leads to the next point, the delete statement. The delete statement must look like

delete from mytable WHERE id = '$id'

But don't do it this way, because this is unsafe and invites all sorts of SQL injection. Better use prepared statments, e.g.

delete from mytable WHERE id = ?

and bind $id when you execute the prepared statement.

edited Nov 17, 2023 at 19:30

CommunityBot

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answered Jun 9, 2014 at 15:19

Olaf Dietsche

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