[英]How do I get a count of each value, based from another table?
我有一个志愿者_2009 表,列出了所有志愿者和一个场地表,列出了志愿者可以分配到的场地,他们只分配给一个。
我想做的是打印出分配到每个场地的志愿者人数。
我希望它像这样打印出来:
地点名称:志愿者人数
表:志愿者venue_id
列:id、name、 venue_id
表:场地列:id、venue_name
他们通过volunteers_2009.venue_id = venues.id
联系起来
这就是我所拥有的,但它无法正常工作。
$sql = "SELECT venues.venue_name as 'Venue', COUNT(volunteers_2009.id) as 'Number Of
Volunteers' FROM venues ven JOIN volunteers_2009 vol ON
(venues.id=volunteers_2009.venue_id) GROUP BY venues.venue_name ORDER BY
venues.venue_name ASC";
$result = mysql_query($sql);
while(list($name,$vols) = mysql_fetch_array($result)) {
print '<p>'.$name.': '.$vols.'</p>';
}
不是 MySQL 人,所以这可能真的是错误的,但是当你给你的表一个别名时,你不需要用那个名字来引用它。
$sql = "SELECT ven.venue_name as 'Venue', COUNT(vol.id) as 'Number Of
Volunteers' FROM venues ven JOIN volunteers_2009 vol ON
(ven.id=vol.venue_id) GROUP BY ven.venue_name ORDER BY ven.venue_name ASC";
$query = "SELECT ven.venue_name AS 'Venue', count(*) AS 'Number of venues'
FROM volunteers_2009 AS vol, venues AS ven WHERE vol.venue_id = ven.id
GROUP BY ven.venue_name";
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