php - 如果满足列的条件，则随机选择行

Question

我的 ads_man 表具有以下结构；

如果“旋转”列为 1，我想从该表中随机选择行，否则如果旋转 = 0，则不应随机选择这些行。我试过这个；

$query = $db->query("
    SELECT type,place,code
    FROM ads_man
    WHERE approved = '1' AND fid = '{$fid}' AND place = '{$zone}'
    ORDER BY RAND()
    LIMIT 3");

它随机选择行，但问题是我找不到快速选择这些行的方法，而是使用另一个查询来查找所有具有 rotate = 1 的行，然后ORDER BY RAND()在上述查询中使用。

请帮忙！

Answer 1

$query = $db->query("
    SELECT type,place,code
    FROM ads_man
    WHERE rotate='1' AND approved = '1' AND fid = '{$fid}' AND place = '{$zone}'
    ORDER BY RAND()
    LIMIT 3");

Answer 2

做这件事有很多种方法：

目前还不是很清楚你需要什么，但是，如果你需要rotate = 1随机选择 3 行，然后是其他行（例如 7 行），rotate = 0那么你可以用UNION

(SELECT type,place,code
    FROM ads_man
    WHERE rotate = 1 AND approved = '1' AND fid = '{$fid}' AND place = '{$zone}'
    ORDER BY RAND()
    LIMIT 3)
UNION
(SELECT type,place,code
    FROM ads_man
    WHERE rotate = 0 AND approved = '1' AND fid = '{$fid}' AND place = '{$zone}'
    LIMIT 7)

这是你需要的吗？如果没有，请告诉我

编辑：忘记括号

Answer 3

我认为最好ALTER在给定表中按语句添加随机数列。这将节省大量时间。

Answer 4

试试这个;

$r_q = $db->query("SELECT rotate FROM ads_man");
$r = $db->fetch_array($r_q);
if($r['rotate'] == "1")
{
    $rotate = 'rotate = "0" OR rotate = "1" AND';
    $order_by = 'ORDER BY RAND()';
}
else
{
    $rotate = 'rotate = "0" AND';
    $order_by = 'ORDER BY dateline DESC';
}

$query = $db->query("
    SELECT type,place,code
    FROM ads_man
    WHERE {$rotate} approved = '1' AND fid = '{$fid}' AND place = '{$zone}'
    {$order_by}
    LIMIT 3");