Solved

Best practice for checking value of a field in php/mysql?

Posted on 2011-09-06
2
273 Views
Last Modified: 2012-06-27
Hi,
in my app I need to check the value of a field and based on that, insert new value or not.
What I'm currently doing is:

 
$result = mysql_query("SELECT subscribestatus FROM callers WHERE FromCaller = '$From'");
	while ($row = mysql_fetch_assoc($result)) {
	$status = $row["subscribestatus"];
	}

Open in new window


Then once its assigned as a variable, I use a switch/case statement to check the value compared to the 3 different ones it may be. Then if it matches one of them, I do an update statement something like this:

 
mysql_query("UPDATE callers SET subscribestatus = 'Subscribed' WHERE FromCaller = '$From' AND subscribestatus = 'Pending'");?>

Open in new window


So my question is: is that the best way to do it? Seems like a lot of work to do a comparison of one value. I just get a nagging suspicion there is a better way.

Thanks tj
0
Comment
Question by:tjyoung
2 Comments
 
LVL 110

Accepted Solution

by:
Ray Paseur earned 250 total points
ID: 36490050
Regarding this: $status = $row["subscribestatus"];

You do not need to do that.  $row["subscribestatus"] is already its own variable.  There is no value added by proliferating variables.  You can use switch / case on the original element of the $row array

Your design pattern makes sense to me as you have described it here.  The things I would be concerned about include the origin and sanitization of the $From variable, and the absence of the LIMIT clause in your queries.

HTH, ~Ray
0
 
LVL 27

Expert Comment

by:skullnobrains
ID: 36490057
you can perform a single SQL query using an if or case statement to update conditionnally to the existing or another value. something like this :

"UPDATE callers SET subscribestatus =
  CASE WHEN (SELECT subscribestatus FROM ...) = 'something_meaning you do not want to update'
  THEN subscribestatus
  ELSE 'Subscribed'
  END WHERE FromCaller = '$From' AND subscribestatus = 'Pending'"

this is already a little better but it will still perform the lookup and lock the row in the callers table

note this will also work if you stick the extra comparison in the where clause

... WHERE ... AND  (select ...) = 'whatever_triggers_the_update'

otherwise you need to go for a transaction : perform the select
SELECT @var:=subscribestatus FROM ...;

CASE when @var == whatever
then UPDATE ...

i'm not completelyy sure about the syntax for the transaction part. feel free to ask if you need more help
0

Featured Post

How Do You Stack Up Against Your Peers?

With today’s modern enterprise so dependent on digital infrastructures, the impact of major incidents has increased dramatically. Grab the report now to gain insight into how your organization ranks against your peers and learn best-in-class strategies to resolve incidents.

Question has a verified solution.

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

Suggested Solutions

Build an array called $myWeek which will hold the array elements Today, Yesterday and then builds up the rest of the week by the name of the day going back 1 week.   (CODE) (CODE) Then you just need to pass your date to the function. If i…
Password hashing is better than message digests or encryption, and you should be using it instead of message digests or encryption.  Find out why and how in this article, which supplements the original article on PHP Client Registration, Login, Logo…
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
The viewer will learn how to create and use a small PHP class to apply a watermark to an image. This video shows the viewer the setup for the PHP watermark as well as important coding language. Continue to Part 2 to learn the core code used in creat…

730 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