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PHP MySQL UPDATE not working, need to use REPLACE

Hi Experts

I have a small script that was working well, since updating the server it runs on I have hit an issue (I dont know if this is related or not)

I have the following code that updates a row in a MySQL Database:

$mastercategory=$_POST['mastercategory']; 
$category=$_POST['category']; 
$product_desc=$_POST['product_desc'];
$barcode=$_POST['barcode'];
$serial=$_POST['serial'];
$status=$_POST['status'];

// update data in mysql database 
$sql="UPDATE $tbl_name SET status='$status' WHERE barcode='$barcode'";
 $result=mysql_query($sql);

// if successfully updated. 
if($result){
 echo "Success";
 echo "<br />";
 echo "Database Checked OK";
  }

 else {
 echo "ERROR";
 }
?>

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If there is already a value in the status field, then the row doesnt update, and the row also isnt updated with a new timestamp.

I think the following piece of code needs to be replaced with a REPLACE function but I am unsure how it would work:

$sql="UPDATE $tbl_name SET status='$status' WHERE barcode='$barcode'";
 $result=mysql_query($sql);

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Your help is greatly appreciated

Jon CAsked: 2013-10-22

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LVL 111

Ray PaseurConnect With a Mentor Commented: 2013-10-22

The issue is if status field it already has the value "CheckedOK", then it doesnt update the timestamp ...

That is expected behavior. The timestamp is only updated if data was actually changed in the row.

Do you expect the barcode to be UNIQUE? If so, adding LIMIT 1 to the UPDATE query would be a good idea. It would also be a good idea to sanitize and escape the external inputs before using them in a query!

The update query you posted appears to be OK. What is not OK is the use of the MySQL extension. PHP is doing away with MySQL. This article explains why and what you must do to keep your scripts running.
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/PHP_Databases/A_11177-PHP-MySQL-Deprecated-as-of-PHP-5-5-0.html

LVL 84

Dave BaldwinFixer of ProblemsCommented: 2013-10-22

There is no REPLACE function in MySQL and there is nothing wrong with the code you have posted. However, it is not complete. $tbl_name is not defined in the code you have posted. What I would do is 'echo' the SQL string right after you create it to make I was getting what I thought I should.

$sql="UPDATE $tbl_name SET status='$status' WHERE barcode='$barcode'";
echo $sql;
$result=mysql_query($sql);

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Jon CAuthor Commented: 2013-10-22

Hi

Thanks for your reply

I have added the code you suggest and it gives the following which is correct:

UPDATE main_stock SET status='CheckedOK' WHERE barcode='039718'

The issue is if status field it already has the value "CheckedOK", then it doesnt update the timestamp on that row, if the status field is empty or has a different value to "CheckedOK" then it updates as it should.

So I suppose the question is how to I get it to update the field status with "CheckedOK" even if that field already has that value, so that the timestamp field gets updated ??

Sorry also tbl_name is definied within the connection to the db as follows:

$tbl_name="main_stock"; // Table name

Thanks for your assistance

LVL 84

Dave BaldwinFixer of ProblemsCommented: 2013-10-22

Then you have to update the timestamp itself in your statement.

By the way, there is a REPLACE command but it does not do what you want. http://dev.mysql.com/doc/refman/5.5/en/replace.html

Jon CAuthor Commented: 2013-10-22

Thanks for your reply again

So if I get it to update the timestamp as you suggest, which sounds logical, is there a way to also get it to add "CheckedOK" to the status field if it doesnt exist, but to ignore it if it does exist so it wont stop the update from working ??

I need the field "status" to be changed to "CheckedOK" if it doesnt have that value.

Thanks again for your assistance

LVL 84

Dave BaldwinFixer of ProblemsCommented: 2013-10-22

?? Just update the timestamp in the same UPDATE statement. I don't know how you are creating your timestamp but the update should probably be the same.

LVL 27

ZberteocCommented: 2013-10-22

First, the timestamp column will not be updated by default unless you define a trigger on the table. Any column you need to modify has to be part of the UPDATE... SET column list.

Second, if the value of status is the same, why do you want to change the timestamp value?

LVL 111

Ray PaseurConnect With a Mentor Commented: 2013-10-22

Here are the essential moving parts (but still using the deprecated MySQL extension). The article will show you how to map this code to the newer MySQLi or PDO extensions. I have found the easiest conversion from MySQL is to use the MySQLi Object-Oriented notation.

// ASSUMING THAT $tbl_name GETS DEFINED SOMEWHERE

/* THESE LINES ARE NOT USED
$mastercategory=$_POST['mastercategory']; 
$category=$_POST['category']; 
$product_desc=$_POST['product_desc'];
$serial=$_POST['serial'];
*/

// ESCAPE DATA FOR SAFE USE IN A QUERY
$barcode = mysql_real_escape_string($_POST['barcode']);
$status  = mysql_real_escape_string($_POST['status']);

// BUILD THE QUERY STRING AND RUN THE QUERY
$sql="UPDATE $tbl_name SET status='$status' WHERE barcode='$barcode' LIMIT 1";
$res = mysql_query($sql);

// TEST FOR SUCCESS, LOG AND SHOW ANY ERROR
if (!$res)
{
    $err
    = "QUERY FAIL: "
    . $sql
    . ' ERRNO: '
    . mysql_errno()
    . ' ERROR: '
    . mysql_error()
    ;
    trigger_error($err, E_USER_ERROR);
}

// IF WE GET HERE, THE UPDATE SUCCEEDED
echo "Success";
echo "<br />";
echo "Database Checked OK";