php - 如何连接两个表以查看两个表中是否存在值

Question

我在将以下查询连接在一起以使其更有效地工作时遇到问题。有人可以告诉我如何连接这两个查询以便它只有一个吗？

$rs_duplicate = mysql_query("select count(*) as total 
                             from advertisers_account
                             where user_email='$user_email' ") or die(mysql_error());

list($total) = mysql_fetch_row($rs_duplicate);

    }

$rs_duplicate_pub = mysql_query("select count(*) as total 
                                 from publishers_account
                                 where user_email='$user_email' ") or die(mysql_error());

list($totalpub) = mysql_fetch_row($rs_duplicate_pub);


if ($totalpub ||  $total  > 0)
{
    echo "Not Available  ";

} else {

    echo "Available";
}

Answer 1

使用联合:

SELECT 'advertisers' AS which, count(*) AS total
FROM advertisers_account
WHERE user_email = '$user_email'
UNION
SELECT 'publishers' AS which, count(*) AS total
FROM publishers_account
WHERE user_email = '$user_email'

此查询将返回两行，您可以使用which 列来判断它是广告商还是发布商。