Checking for NULL values

rheroux

Okay, I've created this little script that accesses my database and pumps out product codes based on a previously inputted customer code.

It all works fine, but now I'm trying to check so that if the customer inputted a customer code that doesn't exist in the database, the script will echo something like, "Sorry, that customer code doesn't exist."

Here's a bit of the code:

$custcode = strtoupper($custcode);
$dbcx = odbc_connect("GROSSMARGIN","usernamehere","passhere",SQL_USE_CUR_DRIVER);
$cur1=odbc_exec($dbcx,"select distinct item_code from opcsahf where cust_code = '$custcode'");
while (odbc_fetch_row($cur1))
{
$item_code = odbc_result($cur1,1);
if ($item_code == " "){
echo "Sorry, that customer code was not found in our database!";
}
else
{
if ($item_code == 'NONINVENTORY')
{
}
else{
@$option_block .="<option value=\"$item_code\">$item_code</option>";
}
}
}
echo "<select name=itemcode>";
echo "$option_block";
echo "</select>";

As you can see, I tried checking to see if $item_code was equal to well nothing, and that didn't work. If the customer code doesn't exist in the database, then the query should come out as false shouldn't it? I've tried a whole bunch of things and I'm stumped.

Thanks for any information.

devinemke

if (!$item_code)
{
echo 'Sorry, that customer code was not found in our database!';
}

rheroux

Nope, that didn't seem to work. Here's the updated code with what you suggested.

$custcode = strtoupper($custcode);
$dbcx = odbc_connect("GROSSMARGIN","usernamehere","passhere",SQL_USE_CUR_DRIVER);
$cur1=odbc_exec($dbcx,"select distinct item_code from opcsahf where cust_code = '$custcode'");
while (odbc_fetch_row($cur1))
{
$item_code = odbc_result($cur1,1);
if (!$item_code){
echo "Sorry, that customer code was not found in our database!";
}
if ($item_code == 'NONINVENTORY')
{
}
else{
@$option_block .="<option value=\"$item_code\">$item_code</option>";
}
}
echo "<select name=itemcode>";
echo "$option_block";
echo "</select>";

gigowiz

Originally posted by rheroux
...

if ($item_code == " "){
echo "Sorry, that customer code was not found in our database!";
}

It looks to me like you have a space between the quote marks. Try using "" instead. However, I normally check the length of the string. If it's = 0, then I assume it's a NULL.

if (strlen($item_code) == 0)

Hank

rheroux

I've found a solution, although it's a bit redundant. I figured out that because the query was returning nothing, the while loop wasn't executing, therefore none of the variables declared in the while loop meant anything.

This is what I've done. Maybe some of you PHP Gurus can come up with an easier way so that I don't have to make the same query twice 😉

<?php
define ("NL","\n");
echo "<head>".NL;
echo "<title>Results</title>".NL;
echo "</head>".NL;
$custcode = strtoupper($custcode);
$dbcx = odbc_connect("GROSSMARGIN","","",SQL_USE_CUR_DRIVER);
$cur1=odbc_exec($dbcx,"select distinct item_code from opcsahf where cust_code = '$custcode'");
$error = odbc_fetch_row($cur1);
$error_message = odbc_result($cur1,1);
if ($error_message == 0) {
echo "Sorry, that customer code was not found in our database!".NL;
echo "<form action=itemcode.php method=POST>".NL;
echo "Customer Code:".NL;
echo "<input type=text maxsize=6 size=6 name=custcode>".NL;
echo "<br>".NL;
echo "<br>".NL;
echo "<input type=submit name=submitorder value=submit>".NL;
echo "</form>".NL;
echo "</body>".NL;
echo "</html>".NL;
odbc_free_result($cur2);
}
$cur = odbc_exec($dbcx,"select distinct item_code from opcsahf where cust_code = '$custcode'");
while (odbc_fetch_row($cur))
{
$item_code = odbc_result($cur,1);
if ($item_code == 'NONINVENTORY')
{
}
else{
@$option_block .="<option value=\"$item_code\">$item_code</option>".NL;
}
}
if ($error_message == 0)
{
}
else {
echo "<select name=itemcode>".NL;
echo "$option_block".NL;
echo "</select>".NL;
}
odbc_free_result($cur);
odbc_close($dbcx);
?>

Thanks for the help folks.

keith73

Originally posted by gigowiz

It looks to me like you have a space between the quote marks. Try using "" instead. However, I normally check the length of the string. If it's = 0, then I assume it's a NULL.

if (strlen($item_code) == 0)

Hank

I'd take that one step further, make sure that the input isn't just a blank space.

if(strlen(trim($item_code)) == 0)

this removes whitespace from before and after the string, so if there is no data but a blank space entered, it will remove that , then check the length.

majik-sheff

Here's a much cleaner (and faster) way to do what you want:
(I took the entire block of code you provided and reworked it here)

$custcode = strtoupper($custcode);
$dbcx = odbc_connect("GROSSMARGIN","usernamehere","passhere",SQL_USE_CUR_DRIVER);
$cur1=odbc_exec($dbcx,"select distinct item_code from opcsahf where cust_code = '$custcode'");
if (odbc_num_rows($cur1) > 0) {
 while (odbc_fetch_row($cur1)) {
  $item_code = odbc_result($cur1,1);
  if ($item_code != 'NONINVENTORY') {
   @$option_block .="<option value=\"$item_code\">$item_code</option>";
  }
 }
} else {
 echo "Sorry, that customer code was not found in our database!";
}
echo "<select name=itemcode>";
echo "$option_block";
echo "</select>";

Hope that helps.

mcgiddin

Why wouldn't empty( $var ) or is_set( $var ) not work?

.\ .\ \

majik-sheff

There's no reason they wouldn't work, it's a matter of code cleanliness and performance. My code starts out by checking to see if any rows were returned. If nothing came back, the loop never even starts and execution time/memory is saved. If a result was returned, it then starts looping through each item and displaying it if it's in inventory.

There are hundreds of ways that this task could conceivably be accomplished, the real art of coding is to find the most elegant one.

mcgiddin

Ok thats cool, I was asking because I use them all of the time and wondered if there was something that I didn't know that I should. : )

Thanks,
.\ .\ \