mysql - 在 MySQL 中查找 SUM 的最大值

Question

大家好 目前我正在为我的商品制作 PHP(库存管理)，在我的系统中客户可以购买商品，我将客户 ID 和已售商品的数量保存在 MySQL 的一个表(称为销售表)中，现在我想展示最好的客户。(谁在我的系统中购买了最多的商品) 我写了一个代码来找出每个客户购买了多少商品，但我不知道如何向最好的客户展示 看这段代码:

$test= "SELECT c_id, SUM(n_sell) FROM sell GROUP BY c_id "; 
$resut = mysql_query($test) or die(mysql_error());
while($t = mysql_fetch_array($resut)){
    echo "Number of sold: ". $t['SUM(n_sell)'] ." to". $t['c_id'] .":id of customer";
    echo "<br />";
}

它向我的所有客户显示已售商品的数量，我需要显示拥有最大销售商品数量的特定客户。 例如，这是我的结果:

Number of sold: 11 to 2 :id of customer Number of sold: 103 to 3: id of customer

但我想要的只是展示:

Number of sold :103 to 3 :id of customer

我希望你们能得到我， 谢谢。

Answer 1

试试这个:

$test = "SELECT c_id, MAX(Bought) AS MaxBought FROM (SELECT c_id, SUM(n_sell) AS Bought FROM sell GROUP BY c_id) AS tmp HAVING MAX(Bought) = tmp.Bought"; 
$resut = mysql_query($test) or die(mysql_error());
while($t = mysql_fetch_array($resut)){
    echo "Number of sold: ". $t['MaxBought'] ." to". $t['c_id'] .":id of customer";
    echo "<br />";
}

为了便于理解，这里单独使用 SQL 查询:

SELECT c_id, MAX(Bought) AS MaxBought
FROM (SELECT c_id, SUM(n_sell) AS Bought
      FROM sell
      GROUP BY c_id) AS tmp
HAVING MAX(Bought) = tmp.Bought