HTML form, set blank form to NULL - php

Question

I have a HTML form; I want to be able to set it so that if a field is empty, the field in the DB will actually be NULL and not just have the word NULL in the field. I thought that using this code would help, but it just puts the word NULL in the field.
PHP Code:
<pre>
<?php
if (isset($_POST['oc_item'])) {
$oc_item = mysql_escape_string($_POST['oc_item']);
$oc_itemdesc = (!empty($_POST['oc_itemdesc'])) ? $_POST['oc_itemdesc'] : NULL;
$sql = "INSERT INTO catalog_dev (oc_item,oc_itemdesc)
VALUES(''$oc_item','$oc_itemdesc')";
mysql_query($SQL);
if (mysql_query($sql)) {
echo '<strong><em>Your data has been submitted</em></strong><br /><br />';
} else {
echo '<p>Error adding submitted info: ' . mysql_error(). '</p>';
}
}
?></pre>
HTML Code:
<pre>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<table>
<tr>
<td>Item Name</td>
<td><input class="forms" type="text" size="50" maxlength="50" name="oc_item" /></td>
</tr>
<tr>
<td>Item Description</td>
<td><input class="forms" type="text" size="50" maxlength="50" name="oc_itemdesc" /></td>
</tr>
</table>
<p><input type="submit" value="Submit item" /></p>
</form></pre>
I want the field to actually be NULL and not have the field contain the word NULL. Thanks in advance.

Answer 1

If you want to write NULL to a MySQL database, you really have to put NULL there without quotation marks.
Like this:
INSERT INTO table (column, column2) VALUES ('mystring', NULL);
It’s always a bit effort if you want to do this manually by hand, because you would have to make if-conditions for the query.
Remember: PHP null != MySQL NULL. They both do not know each other at all.
But I am still wondering, what does that all have to do with the question name? (SELECT unless)
You could write your code like this:
$oc_item = mysql_escape_string($_POST['oc_item']);
$oc_itemdesc = (isset($_POST['oc_itemdesc']) && trim($_POST['oc_itemdesc']) != '') ? "'" . mysql_escape_string($_POST['oc_itemdesc']) . "'" : 'NULL';
$sql = "INSERT INTO catalog_dev (oc_item,oc_itemdesc)
VALUES('" . $oc_item . "', " . $oc_itemdesc . ")";
# sorry for adding " . all the time, but I dislike variables within strings :D
But I have to admit I do not like that much either, as it moves the duty to wrap quotation marks around MySQL strings away from the SQL-query itself.

Answer 2

If you printed out $sql, you'd see that it's inserting , 'NULL'.
You need to modify your code so that it inserts the work "NULL" (without '' quotes) or, better, doesn't insert that parameter at all (eliminate the entire , 'NULL' part of the string.

Answer 3

Try this:
$oc_itemdesc = (!empty($_POST['oc_itemdesc'])) ? "'".$_POST['oc_itemdesc']."'" : "NULL";
$sql = "INSERT INTO catalog_dev (oc_item,oc_itemdesc)
VALUES('$oc_item',$oc_itemdesc)";
As it stands you are adding 'NULL' instead of NULL so it is adding the words instead of the value.
Side Note: I would be careful and properly escape/encode the $_POST['oc_itemdesc'] as someone who put an apostrophe in the description would completely throw off the insert statement. For example: I don't like this would look like this:
$sql = "INSERT INTO catalog_dev (oc_item,oc_itemdesc)
VALUES('$oc_item','I don't like this')";//MYSQL Error
PPS: As it stands you are inserting TWICE:
mysql_query($SQL);//insert 1
if (mysql_query($sql)) {//insert 2

Answer 4

The function that I use for the MySQL data from the HTML forms.
function emptyHtmlFormToNull($arr){
foreach($arr as $key => $val){
if(empty($val) || strtolower($val) === 'null'){
$arr[$key] = null;
}
}
return $arr;
}