在group by 2 column，然后group by 1列中是否需要2个查询？

Question

我有一个包含电子邮件地址的表(列: id、电子邮件、用户、日期)。我尝试通过日期和用户来计算电子邮件地址的总和，我可以使用下面的代码来实现；但是也可以将所有用户的总地址相加，并将其显示在该日期之下。我不知道该怎么做。我是否需要对每个日期的合计进行另一次查询？

$sql = mysql_query("SELECT date, COUNT(email), user FROM emails GROUP BY DATE(date), user");
while ($row = mysql_fetch_array($sql)){
  echo date('m/d', strtotime($row['date'])) . " " . $row['user'] . " " . $row['COUNT(email)'] . "<br />";
}

我所拥有的：

date user count(email)
09/09 29 8
09/09 49 9
09/10 29 4
09/10 49 13
09/11 29 1
09/11 49 3

我想要的：

date user count(email)
09/09 29 8
09/09 49 9
09/09 total 17

09/10 29 5
09/10 49 13
09/10 total 18

09/11 29 1
09/11 49 3
09/11 total 4

谢谢

编辑:以下是我的代码：

$sql = mysql_query("SELECT date, COUNT(email), user FROM emails GROUP BY DATE(date), user WITH ROLLUP");

while ($row = mysql_fetch_array($sql)){
  echo date('m/d', strtotime($row['date'])) . " " . (!isset($row['user']) ? 'total' : $row['user']) . " " . $row['COUNT(email)'] . "<br />";
}

Answer 1

请参见 ( GROUP BY修改器)。

SELECT DATE(`date`) AS date
     , user 
     , COUNT(email) AS cnt
FROM emails 
GROUP BY DATE(`date`)
       , user 
WITH ROLLUP 

会给你带来：

date    user   cnt
09/09   29       8
09/09   49       9
09/09   NULL    17

09/10   29       5
09/10   49      13
09/10   NULL    18 

09/11   29       1
09/11   49       3
09/11   NULL     4

NULL    NULL    39

Answer 2

我认为你可以使用UNION ALL来做这件事。它是这样的：

SELECT date, COUNT(email), user
FROM emails
GROUP BY DATE(date), user
UNION ALL
SELECT date, COUNT(email), -1
FROM emails
GROUP BY DATE(date)
ORDER date ASC

或者你可以用PHP的方式：

$previousDate = null;
$total = 0;
$sql = mysql_query("SELECT date, COUNT(email), user FROM emails GROUP BY DATE(date), user");
while ($row = mysql_fetch_array($sql)){
    if ($previousDate != date('m/d', strtotime($row['date']))) {
        echo $previousDate . " total " . $total . "<br /><br />";
        $total = 0;
        $previousDate = date('m/d', strtotime($row['date']));
    }

    echo date('m/d', strtotime($row['date'])) . " " . $row['user'] . " " . $row['COUNT(email)'] . "<br />";
    $total = $total + $row['COUNT(email)'];
}