Solved

How to insert null value into MySQL database when using PHP variables

Posted on 2009-05-03
3
744 Views
Last Modified: 2012-06-21
It sure looks like what I'm doing is correct, but MySQL is giving me a syntax error and I cannot figure out why.

I have a field called "staples". It's defined as DECIMAL 10,2. It is set so that a NULL value is allowed. I submit a form and populate the field with the value of 100. All is well. I go back and change the value on the form to essentially erase it - I backspace over it. The code to process the value is this:

$value = $_POST['staples'];

$query = "UPDATE tblSurveys SET staples = {$value} WHERE ansID = 43";

The query throws a syntax error.
Note that if I have entered a value like 100 into the field, the query works fine.

What am I missing?

I put some logic in to check to see if $_POST['staples'] is set, and it is - even when I've backspaced over the field. So what does post return if the field is empty? I tried to add this check:

if ($value == "") { $value = NULL; } but that doesn't help. Still get the syntax error.
0
Comment
Question by:alicia1234
3 Comments
 
LVL 142

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 24290735
if (isset($_POST['staples']) && ($_POST['staples'] != "") )
{
  $value = $_POST['staples'];
}
else
{
  $value = "NULL";
}

$query = "UPDATE tblSurveys SET staples = {$value} WHERE ansID = 43";
0
 
LVL 28

Expert Comment

by:gamebits
ID: 24290736
try

$query = "UPDATE tblSurveys SET staples = '$value' WHERE ansID = 43";
0
 

Author Comment

by:alicia1234
ID: 24290826
gamebits stopped the error but put a 0.00 in the database field; what I wanted in the field was NULL. angelIII's solution both fixed the syntax error and put the NULL value in the field

Thanks!

0

Featured Post

Comprehensive Backup Solutions for Microsoft

Acronis protects the complete Microsoft technology stack: Windows Server, Windows PC, laptop and Surface data; Microsoft business applications; Microsoft Hyper-V; Azure VMs; Microsoft Windows Server 2016; Microsoft Exchange 2016 and SQL Server 2016.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
how can i gnupg encrypt a PDF document? 12 24
preventing spam with mailto 22 29
Google Maps API and PHP 25 27
PHP AJAX Wordpress 9 19
Developers of all skill levels should learn to use current best practices when developing websites. However many developers, new and old, fall into the trap of using deprecated features because this is what so many tutorials and books tell them to u…
Load balancing is the method of dividing the total amount of work performed by one computer between two or more computers. Its aim is to get more work done in the same amount of time, ensuring that all the users get served faster.
The viewer will learn how to dynamically set the form action using jQuery.
The viewer will learn how to count occurrences of each item in an array.

815 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

13 Experts available now in Live!

Get 1:1 Help Now