Using Session IDs to filter Recordset isn't looping through all of the IDs

I seem to be tripping over some basics here. Not sure what I am forgetting.
I am filtering a recordset from stored $_SESSION(s) BUT it's only filtering to the first ID of each $_SESSION.

Basically I have a 3 Step form that builds up ID's as they are selected and posted.
They are stored in $_SESSION(s,) one for each page.

The sessions are being stored ok as I move through each step.
By checking the final page using…

var_dump($_SESSION);

I get…

array(3) {
["Step_1"]=>
string(1) "5"
["Step_2"]=>
string(8) "51,13,20"
["Step_3"]=>
string(3) "2,6"
}

Recordset:

$ParamID_Recordset1 = "-1";

if (isset($_SESSION['Step_1'])) {

  $ParamID_Recordset1 = $_SESSION['Step_1'];

}

$ParamID_Recordset1 = "-1";

if (isset($_SESSION['Step_2'])) {

  $ParamID_Recordset1 = $_SESSION['Step_2'];

}

$ParamID_Recordset1 = "-1";

if (isset($_SESSION['Step_3'])) {

  $ParamID_Recordset1 = $_SESSION['Step_3'];

}

mysql_select_db($database_dbProducts, $dbProducts);

$query_Recordset1 = sprintf("SELECT ProductID FROM tblProducts WHERE ProductID = %s OR ProductID = %s OR ProductID = %s", GetSQLValueString($ParamID_Recordset1, "int"));

$Recordset1 = mysql_query($query_Recordset1, $dbProducts) or die(mysql_error());

$row_Recordset1 = mysql_fetch_assoc($Recordset1);

$totalRows_Recordset1 = mysql_num_rows($Recordset1);

My results show only the first ID from each session, so obviously it's not looping through the entire session.
Do I need loop through all of the ids somehow? I figured the string in each session would do that?

Thanks,
TroyD

you need to concatenate the 3 sessions into one, then use IN in your rrecordset:

http://www.w3schools.com/sql/sql_in.asp

Jason,

Thanks. That's what I was needing.
I'm mot sure if my use of ternary operators in the concatenation is correct but it is working.( I need the ternary operators for something else I am trying to work on.)

Here is what I ended up with.

<?php

session_start();

$id[] = ($_SESSION['Step_1'] >= 1 ? $_SESSION['Step_1'] : '') . "," . ($_SESSION['Step_2'] >= 1 ? $_SESSION['Step_2'] : '') . "," . ($_SESSION['Step_3'] >= 1 ? $_SESSION['Step_3'] : '');

foreach ($id as $key => $pid){

}

?>

Recordset:

SELECT ProductID FROM tblProducts WHERE ProductID IN ($pid)

Thanks,
TroyD