Question

这是我目前的MySQL表：

Crop             ID  Price  DateUpdated             Area       Region
Onion            4   50     2014-02-05 21:42:26     Bulua      X
Onion            5   20     2014-02-05 21:42:26     Lapasan    X
Onion            14  34.4   2014-02-05 23:12:21     Cogon      X
Onion            15  54     2014-02-07 02:40:13     Cogon      X
Onion            15  84     2014-02-07 02:40:13     DMarket    XI

我希望使用最新的'Crops'及其对应的'Price'输出所有'Region'。因此，包含具有最新价格的特定Product和Region的条目是我所需要的。

假设：

$product = 'Onion';
$region = 'X';

查询为：

$crop_multi = $db->query("SELECT Crop, Price, Area, Region  
                FROM crops cr WHERE TRIM(Crop) = '{$product}' 
                AND DateUpdated = (SELECT MAX(DateUpdated) FROM crops WHERE Crop = cr.Crop AND TRIM(Crop) = '{$product}' AND TRIM(Region) = '{$region}')");
$message = "Price of {$product} in markets of Region {$region}:<br>";

            foreach ($crop_multi->fetchAll(PDO::FETCH_OBJ) as $row) {
            $add = "P{$row->Price}/kilo in {$row->Area}<br>";
            $message .= $add;
                }
            echo $message;

所需的输出是：

Price of Onion in markets of Region X:
P50/kilo in Bulua
P20/kilo in Lapasan
P54/kilo in Cogon

但是，我上面的代码只输出一行（庄稼与 “{1}}中使用的”最新“价格，即使其他条目符合查询条件。
foreach 循环适用于我的问题的另一种语法，所以我不认为这就是问题所在。
我尝试将$ product更改为$ region，但它会输出多个条目，所以是尝试失败。

编辑：只是澄清一下，上面的代码是一段摘录。我在查询phpmyadmin query function

时遇到问题

Answer 1

这是你要找的吗？

    "SELECT Crop, Price, Area, Region  
    FROM crops cr WHERE TRIM(Crop) = ".$product." 
    AND DateUpdated = (SELECT MAX(DateUpdated) FROM crops WHERE Crop = cr.Crop AND TRIM(Crop) = ".$product." AND TRIM(Region) = ".$region."')"

Answer 2

你可以试试这个。

SELECT DISTINCT Crop, Price, Area, Region FROM crops  tb1
WHERE DateUpdated = (SELECT MAX(DateUpdated) FROM crops tb2 WHERE tb1.Crop = tb2.Crop AND tb1.Area = tb2.Area AND tb1.Region = tb2.Region)
AND TRIM(Crop) = '{$product}' AND TRIM(Region) = '{$region}';

Answer 3

尝试类似：

SELECT Crop, Price, Area, Region
FROM crops cr WHERE TRIM(Crop) = '{$product}'
AND TRIM(Region) = '{$region}'
AND DateUpdated IN(SELECT MAX(DateUpdated) FROM crops WHERE Crop = cr.Crop AND TRIM(Crop) = '{$product}' GROUP BY Crop, Area)

干杯

在Mysql中连接两个AND查询

3 个答案: