PHP/MySQL Select Statement

Question

This one's probably easy:

I have two variables:

$sender_id
$receiver_id

Those ID's are stored and assigned to a user in tblusers. I have no problem selecting one-at-a-time:

$data = mysql_query("SELECT * FROM tblusers WHERE usrID='$receiverID'") or die(mysql_error());

while($row = mysql_fetch_array( $data ))
{
echo $row['usrFirstName'];
echo $row['usrLastName'];
}

However, how would I select both rows (one for senderID and receiverID) so that I can gain access to further information on both those users. Sort of like a "SELECT within a SELECT".

Thanks!

Answer 1

SELECT * FROM tblusers WHERE usrID='$receiverID' or usrID='$sender_id'

EDIT: clarification

while($row = mysql_fetch_array( $data ))
{
    if($row['usrID'] == $receiverID) {
        echo "Receiver: " . $row['usrFirstName'] . " " . $row['usrLastName'];
    } else {
        echo "Sender: " . $row['usrFirstName'] . " " . $row['usrLastName'];
    }

}

Answer 2

If you need to differentiate which is the receiver and which is the sender:

select
    'Receiver' as UserType,
    *
from
    users
where
    usrid = $receiver_id
union all
select
    'Sender' as UserType,
    *
from
    users
where
    usrid = $sender_id

This will return:

UserType  |  UsrID  |  Name
Receiver  |   23    |  John Smith
Sender    |   42    |  Adam Douglas

Of course, with two rows, you can always just compare the ID's to figure that out, too. This is mainly to make scaling easier if you have a larger result set than just two rows.

Answer 3

SELECT * FROM tblusers WHERE usrID IN ($receiverID, sender_id)