php - 如果条件为真，则在使用两个不同的语句时使用 CASE 语句

Question

1. 我需要显示从 Market wise 表中检索的数据。对于每个市场，可以计算和显示订单数量和商品数量。我只有一个栏目，即市场，但我需要以水平方式显示市场。

我已经尝试创建临时表来实现这一点。无论如何我得到了结果，但不准确。

    $MarketQry="SELECT DISTINCT `Market` FROM `orders`";
    $MarketResult=mysql_query($MarketQry,$con);
    $OrdersQry="";
    while($mvalue=mysql_fetch_array($MarketResult))
    {
        $OrdersQry.="CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Count`) ELSE 0 END AS `".$mvalue['Market']." -Number of Orders`, CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Records`) ELSE 0 END AS `".$mvalue['Market']." -Number of Order Line Items`,";              
    }

$createqry="CREATE TEMPORARY TABLE `temp_order_market` AS 
        SELECT ".$OrdersQry."`OrderDate` FROM 
        (SELECT COUNT(DISTINCT `OrderID`) AS `Count`,COUNT(`OrderID`) AS `Records`,`OrderDate`,`Market` 
        FROM `orders` 
        WHERE (`OrderDate` BETWEEN '$StartDate' AND '$EndDate')  
        GROUP BY `OrderDate`) 
        ) AS `dummy` GROUP BY `OrderDate` ORDER BY `OrderDate` DESC";

echo $createqry."<br /><br />"; 

$resQry=mysql_query($createqry,$con) or die(mysql_error($con));

$selectqry="SELECT * FROM `temp_order_market`";

1. 无论我得到什么结果都不准确。因为如果我得到个别市场的结果，我就会得到准确的结果。以下是我用于获取个别市场结果的查询。

   SELECT SUM(`Count`) AS `Orders`,SUM(`Records`) AS `Records`,`OrderDate` FROM 
               (SELECT COUNT(DISTINCT `OrderID`) AS `Count`,COUNT(`OrderID`) AS `Records`,`OrderDate` 
               FROM `orders` 
               WHERE (`OrderDate` BETWEEN '2015-01-01' AND '2015-01-31') AND `Market`='$MarketName' 
               GROUP BY `OrderDate`)) AS `dummy` GROUP BY `OrderDate` ORDER BY `OrderDate` DESC";
   

现在我的问题是:

1. 除了这个方法我们还能做这个吗/这有可能实现我正在使用的方法吗？

2. 我怀疑我编写的查询的 CASE 语句。

请分享您的想法。提前致谢。

Answer 1

将 SUM() 添加到 $OrderQry，它现在工作正常。

旧

$OrdersQry.="CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Count`) ELSE 0 END AS `".$mvalue['Market']." -Number of Orders`, CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Records`) ELSE 0 END AS `".$mvalue['Market']." -Number of Order Line Items`,";

替换为

$OrdersQry.="SUM(CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Count`) ELSE 0 END) AS `".$mvalue['Market']." -Number of Orders`, SUM(CASE WHEN `Market`='".$mvalue['Market']."' THEN SUM(`Records`) ELSE 0 END) AS `".$mvalue['Market']." -Number of Order Line Items`,";