Question

My current queries. Can I combine them in to fewer to get the same result? I am trying to get specific information about the trail into an array named $trail.

$result = mysql_query("SELECT meta_value FROM wp_postmeta WHERE `post_id` = $id AND `meta_key` = 'location_city' ");
$result = mysql_fetch_array($result);
$trail[city] = $result[0];

$result = mysql_query("SELECT meta_value FROM wp_postmeta WHERE `post_id` = $id AND `meta_key` = 'length' ");
$result = mysql_fetch_array($result);       
$trail[length] = $result[0];

$result = mysql_query("SELECT meta_value FROM wp_postmeta WHERE `post_id` = $id AND `meta_key` = 'location_state' ");
$result = mysql_fetch_array($result);
$trail[state] = $result[0];

$result = mysql_query("SELECT meta_value FROM wp_postmeta WHERE `post_id` = $id AND `meta_key` = 'difficulty' ");
$result = mysql_fetch_array($result);
$trail[difficulty] = $result[0];

$result = mysql_query("SELECT guid FROM wp_posts WHERE `post_parent` = $id AND `post_type` = 'attachment' ");
$result = mysql_fetch_array($result);
$trail[image] = $result[0];

Answer 1

If you want the data in columns, then you could JOIN the queries:

SELECT lc.meta_value Location_City,
    l.meta_value Location,
    ls.meta_value LocationState,
    d.meta_value Difficulty,
    p.guid
FROM wp_postmeta lc
LEFT JOIN wp_postmeta l
    on lc.`post_id` = l.`post_id`
    and l.`meta_key` = 'length'
LEFT JOIN wp_postmeta ls
    on lc.`post_id` = ls.`post_id`
    and ls.`meta_key` = 'location_state'
LEFT JOIN wp_postmeta d
    on lc.`post_id` = d.`post_id`
    and d.`meta_key` = 'difficulty'
LEFT JOIN wp_posts p
    on lc.`post_id` = p.`post_parent`
    and p.`post_type` = 'attachment'
WHERE lc.`post_id` = $id 
    AND lc.`meta_key` = 'location_city'