SQL Select查询联接多个表

Question

I have this code:

function getPricing() {
$returnarr = array();
$dcid = (isset($_REQUEST['dcid'])) ? "WHERE datacentre_id='" . mysql_real_escape_string($_REQUEST['dcid']) . "'" : '';

$addons = $_REQUEST['addon'];

if ($addons == "true")
    $sql = "SELECT * FROM addonprices $dcid ORDER BY addon_desc ASC";
else
    $sql = "SELECT l.l_name, p.* FROM pricing p LEFT JOIN locations l ON l.location_id=p.datacentre_id $dcid ORDER BY CASE splitsize WHEN 'f' THEN 0 WHEN 'w' THEN 1 WHEN 'h' THEN 2 WHEN 'q' THEN 3 WHEN '2U' THEN 4 WHEN '1U' THEN 5 ELSE 6 END DESC, amps ASC";

$result = mysql_query($sql);
while ($row = mysql_fetch_assoc($result)) {
    $returnarr[] = $row;
}
header('Content-type: application/json');
echo json_encode($returnarr);
}

I need to add another table into both select statements, joining on the $dcid , the table is called slas and the column is currency I've tried a few things but no luck.

I'm trying to pull the currency into a javascript file to get prices using this switch statement:

var currency = "";

            switch (row.currency) {
                case '1' :
                    currency = "£";
                    break;
                case '2' :
                    currency = " $";
                    break;
                case '3' :
                    currency = "€";
                    break;
                default:
                    currency = "£";
                    break;


            }

and even when currency should equal 2 or 3 it still shows up as the default... I'm not sure if it's the switch statement that's wrong or the sql query.

UPDATE

Just having issues with this one line:

$sql = "SELECT l.l_name, p.*, slas.currency FROM pricing p LEFT JOIN locations l ON l.location_id=p.datacentre_id LEFT JOIN slas ON slas.datacentre_id = p.datacentre_id $dcid ORDER BY CASE splitsize WHEN 'f' THEN 0 WHEN 'w' THEN 1 WHEN 'h' THEN 2 WHEN 'q' THEN 3 WHEN '2U' THEN 4 WHEN '1U' THEN 5 ELSE 6 END DESC, amps ASC";

Taken from an answer below.

Answer 1

I think the issue here is that the unqualified datacentre_id in your WHERE will not allow you to join to another table with a column named datacentre_id

I would suggest the WHERE be

$dcid = (isset($_REQUEST['dcid'])) ? "WHERE p.datacentre_id='" . mysql_real_escape_string($_REQUEST['dcid']) . "'" : '';

and the query be

if ($addons == "true")
    $sql = "SELECT p.*, slas.currency FROM addonprices p LEFT JOIN slas ON slas.datacentre_id = p.datacentre_id $dcid ORDER BY addon_desc ASC";
else
    $sql = "SELECT l.l_name, p.*, slas.currency FROM pricing p LEFT JOIN locations l ON l.location_id=p.datacentre_id LEFT JOIN slas ON slas.datacentre_id = p.datacentre_id $dcid ORDER BY CASE splitsize WHEN 'f' THEN 0 WHEN 'w' THEN 1 WHEN 'h' THEN 2 WHEN 'q' THEN 3 WHEN '2U' THEN 4 WHEN '1U' THEN 5 ELSE 6 END DESC, amps ASC";

notice in both cases the table with datacentre_id in it is aliased p