Check if an info exists, if not create it

stormblast

Hi there,

I got something like:

$sql="SELECT artikel FROM kommentare WHERE artikel = '" . $gwert . "'" ;

"artikel" is a number which is delivered by an URL ( e.g. www.somesite.org/entry.php?artikel=111111 )

Now I need a checkup which operates the following way:

If the article exists just show the content of the table. If that article DOESN'T exist so far, it shall insert the given data into the table.

How's that possible?

Thanks a lot!

laserlight

You have shown some code pertaining to SQL, and you have made mention of a query sting.

Somewhere in between, you need to say how those two work together, as which 'article' you are talking about is ambiguous, at least to me.

stormblast

URL www.somesite.org/entry.php?artikel=111111

$ANr = $_GET["artikel"] ;

$sql="SELECT * FROM kommentare WHERE artikel = '" . $ANr . "'" ;

There I need the following:

If $ANr exists, do nothing just select it.

If $ANr DOESN'T exist, insert the artikel number given by the URL into the database.

Sorry for being unclear before..

laserlight

//validate $_GET['artikel']
if (!empty($_GET['artikel']) && ctype_digit($_GET['artikel'])) {
	$sql = "SELECT * FROM kommentare WHERE artikel='{$_GET['artikel']}'";
	//run the query
	if (/* number of rows returned */ == 0) {
		//insert into kommentare table
	} else {
		//do nothing, the result has been selected
	}
} else {
	//nothing specified
}

stormblast


//validate $_GET['artikel']
if (!empty($_GET['artikel']) && ctype_digit($_GET['artikel'])) {
    $sql = "SELECT * FROM kommentare WHERE artikel='$gwert'";
	$query=mysql_query($sql) or die(mysql_error().'<br />'.$sql);
	$num=mysql_num_rows($query)or die(mysql_error().'<br />'.$sql);
    //run the query

if (/* number of rows returned */ $num == 0) {
	echo 'asdf';
    //insert into kommentare table
} else {

    //do nothing, the result has been selected
}
} else {
    //nothing specified
}

$gwert = artikel

Did I understand you correctly that way? Problem is no result at all pops up.. The database/table is empty at the moment

laserlight

Nope, you must then assign $_GET['artikel'] to $gwert, but frankly I try to minimise the number of variables used.

The code I provided isnt complete, it is partially the statement of a simple algorithm.
You need to fill in the blanks where necessary, e.g. use mysql_num_rows() in place of / number of rows returned /

btw, if you want to use a domain name in an example, use example.com

stormblast

Originally posted by laserlight
Nope, you must then assign $_GET['artikel'] to $gwert, but frankly I try to minimise the number of variables used.

The php code is pretty big, $gwert is being assigned earlier. Just now the MySQL part is starting. Sorry, it's just some value in $gwert which was processed earlier by an URL.

I filled in data into the table now:

$sql = "INSERT INTO kommentare SET artikel='$ANr'";

And changed your code to:

    $sql = "SELECT * FROM kommentare WHERE artikel='$gwert'";

$query=mysql_query($sql) or die(mysql_error().'<br />'.$sql);     //run the query

  if ( mysql_num_rows($query) == 0) {
	echo 'no data';
      //insert into kommentare table
	} else {
	echo 'data available';
        //do nothing, the result has been selected
 }

So in fact "data available" should be displayed, but it displays "no data"

laserlight

$gwert is being assigned earlier

In which case you should perform the validation of $_POST['artikel'] much earlier.
But what's with both $gwert and $ANr?
You should only use one.

stormblast

$ANr includes a big string which is cut down and divided by some checksums. $gwert is the value I need to have in the database. It's just for testing that $ANr is in the DB now.

My main problem is now that I need a if statement which finds out if the given $gwert exists in the database or not. And if it doesn't exist I need it to be inserted into the database.

I'm still stuck here :/


$sql = "SELECT * FROM kommentare WHERE artikel='$gwert'";

$query=mysql_query($sql) or die(mysql_error().'<br />'.$sql);     //run the query

  if ( mysql_num_rows($query) == 0) {
    echo 'no data';
      //insert into kommentare table
    } else {
    echo 'data available';
        //do nothing, the result has been selected
 }

laserlight

dont just echo 'no data', echo the value of $gwert that causes it to have no data.

stormblast

$gwert is now same as artikel in DB (forgotten about that)

It works correctly now with

    $sql = "SELECT * FROM kommentare WHERE artikel='$gwert'";

$query=mysql_query($sql) or die(mysql_error().'<br />'.$sql);     //run the query

  if ( mysql_num_rows($query) == 0) {
	echo "data: '$gwert'";
      //insert into kommentare table
	} else {
	echo 'data available';
        //do nothing, the result has been selected
 }

(Returns: data available)

Thanks a lot for your patience! 🙂