SQL UPDATE value as null or string

Question

I searched almost whole internet, but could not find something similar, yet my question looks so simple.

I have a php code like so:

$id = 1;    
if (!isset($_POST['port1'])) {
        $port1 = null;
    }

... which simply checks if submitted value is empty or not, if it is empty, then variable $port1 = null;

then, further in the code, I need to insert this value/update it in the database

$sql_update = ("UPDATE names_10 SET `digName1`=$port1 WHERE `device_id`='$id'");

...which should set the "digname1" to null. but it won't! I tried every combination, every type of quotes, but every time I got UPDATE error..

any ideas?

null in a string in php is not the same as NULL as a value in a query. I think you should solve this by using parameters rather than munging the string. — Gordon Linoff
– Gordon Linoff, Commented Apr 5, 2017 at 10:44
stackoverflow.com/questions/9314353/set-value-to-null-in-mysql — u_mulder
– u_mulder, Commented Apr 5, 2017 at 10:45
@GordonLinoff What do you mean by "using parameters"? I need to use this variable — David Stančík
– David Stančík, Commented Apr 5, 2017 at 10:45

Satish Saini · Accepted Answer · 2017-04-05 10:51:08Z

1

Try this:

$id = 1;    
if (!isset($_POST['port1'])) {
        $port1 = "NULL";
}

$sql_update = ("UPDATE names_10 SET `digName1`= $port1 WHERE `device_id`='$id'");

I would rather suggest you to use PDO when you plan to bind something like this. There are a lot of benefits using PDO that would amaze you!

answered Apr 5, 2017 at 10:51

Satish Saini

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7 Comments

David Stančík Over a year ago

Okay, i will read about it. And try What? Looks identical to my code ...

Alex Slipknot Over a year ago

case sensitive 'NULL' (that is string and not NULL)

David Stančík Over a year ago

Okay, i will try

Satish Saini Over a year ago

Do you want null as a string in your database?

David Stančík Over a year ago

@SatishSaini boom, after you updated the answer i tried... Now it works!!!!!! Thanks!!!!

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