Set value to NULL in MySQL

Question

I want a value to be set to NULL if nothing is put into the text box in the form I\'m submitting. How can I make this happen? I\'ve tried inserting \'NULL

Answer 1

You're probably quoting 'NULL'. NULL is a reserved word in MySQL, and can be inserted/updated without quotes:

INSERT INTO user (name, something_optional) VALUES ("Joe", NULL);
UPDATE user SET something_optional = NULL;

Answer 2

The answers given here are good but i was still struggling to post NULL and not zero in mysql table.

Finally i noted the problem was in the insert query that i was using

   $quantity= "NULL";
   $itemname = "TEST";

So far so good.

My insert query was bad.

   mysql_query("INSERT INTO products(quantity,itemname) 
   VALUES ('$quantity','$itemname')");

I corrected query to read.

   mysql_query("INSERT INTO products(quantity,itemname) 
   VALUES ('".$quantity."','$itemname')");

So the $quantity is outside of the main string. My sql table now accepted to record null quantity instead of 0

Answer 3

if (($_POST['nullfield'] == 'NULL') || ($_POST['nullfield'] == '')) {
   $val = 'NULL';
} else {
   $val = "'" . mysql_real_escape_string($_POST['nullfield']) . "'";
}

$sql = "INSERT INTO .... VALUES ($val)";

if you put 'NULL' into your query, then you're just inserting a 4-character string. Without the quotes, NULL is the actual null value.