Returning an array using PDO - postgresql

Question

I'm trying to use PDO using the following code, I want to select the array of values for the context_list, but it returns one record, any ideas where I'm going wrong?
try {
$sql2 = "SELECT area_easting, area_northing, context_number FROM excavation.contexts";
$sth = $conn->prepare($sql2);
$sth->execute();
while ($row = $sth->fetch(PDO::FETCH_ASSOC))
{
$easting_list = $row['area_easting'];
$northing_list = $row['area_northing'];
$context_list = $row['context_number'];
}
}
catch(PDOException $e )
{
echo "Error: ".$e;
}
echo "context list: ";
echo $context_list;
A partial solution:
This worked:
$query = $conn->prepare("SELECT area_easting, area_northing, context_number FROM excavation.contexts");
$query->execute();
while($r = $query->fetch(PDO::FETCH_OBJ)){
echo $r->area_easting, '|';
echo $r->area_northing;
echo '<br/>';
}
But Now I need to make the $r->area_easting accessible to the session, but that's another question.

Answer 1

Your query may return several records (provided they actually exist in the table).
Your code loops through all the records (with the while loop) but the values ($easting_list, $northing_list and $context_list) are overwritten in the loop.
I suggest the following changes to your code:
$easting_list = array();
$northing_list = array();
$context_list = array();
try {
$sql2 = "SELECT area_easting, area_northing, context_number FROM excavation.contexts";
$sth = $conn->prepare($sql2);
$sth->execute();
while ($row = $sth->fetch(PDO::FETCH_ASSOC))
{
$easting_list[] = $row['area_easting'];
$northing_list[] = $row['area_northing'];
$context_list[] = $row['context_number'];
}
}
catch(PDOException $e )
{
echo "Error: ".$e;
}
echo "context list: ";
echo implode(', ', $context_list);
Now all the values are stored in 3 arrays. explode is used to print a comma-separated list of all values in $context_list array.