Question

所以我想在表格“食物”中找到一列“卡路里”。但我想找到总和

where a.id = b.foodid 
  AND b.username LIKE '$user' 
  AND b.day='$day' 
  AND b.month LIKE '$month' 
  AND b.year LIKE '$year' ORDER by b.id DESC

目前我有这个：但它不起作用

$caloriesum = mysql_fetch_assoc(mysql_query("SELECT SUM(calories) 
                                               FROM foods a, 
                                                    user_foods b 
                                              WHERE a.id = b.foodid 
                                                AND b.username LIKE '$user' 
                                                AND b.day='$day' 
                                                AND b.month LIKE '$month' 
                                                AND b.year LIKE '$year' 
                                           ORDER BY b.id DESC")) or die(mysql_error());

然后我稍后让剧本回显总和。

            echo('  
            <tr class = "db-out-head">
            <td><b>Totals</b></td>
            <td></td>
            <td></td>
            <td>'.$caloriesum[0].'</td>
            <td></td>
            <td></td>
            <td></td>
            </tr>');

我在空桌上看到的一切。

Answer 1

删除你的ORDER BY :)，所以这样的sql：）

SELECT SUM(calories) FROM foods a, user_foods b WHERE a.id = b.foodid AND b.username LIKE '$user' AND b.day='$day' AND b.month LIKE '$month' AND b.year LIKE '$year'

Answer 2

如果您正在寻找完全匹配，请使用等于运算符。试试这个问题：

SELECT SUM(calories) FROM foods a INNER JOIN
user_foods b ON a.id = b.foodid AND b.username LIKE '$user' 
AND b.day='$day' AND b.month LIKE '$month' AND b.year LIKE '$year'

Answer 3

由于您创建关联数组$calories[0]将无效。在查询中为该总和命名，并将其用作数组索引。

在表B中使用条件时在表A中添加列

3 个答案: