小编php*_*pJs的帖子

在MySQL中我有两个表:

Table MC:
----------------
|TransNo | Qty |
|--------|-----|
|  xxx1  |  4  | 
|  xxx3  |  3  |

和

Table Amex:
----------------
|TransNo  | Qty |
|---------|-----|
|  xxx1   |  2  |
|  xxx5   |  1  | 

我需要将Qty表MC(方程式7)和表Amex(方程式3)中的列相加,得到总数量的结果.

当我做

SELECT (SUM(amex.Qty) + SUM(mc.Qty)) as total_qty from amex, mc

我得到了笛卡尔积(20),但我需要的正确答案是10.我如何更改此查询以获得正确的结果？

我需要将数据库值与post值进行比较.如果发布值(十进制价格)在2美分阈值内,则考虑值相等.结果是具有"真实"差异的数组.数组是一致的:相同数量的值,相同的键.

$db_values =   array( "21" => 10.00, "22" => 20.00, "25" => 3.55);
$post_values = array( "21" => 9.98,  "22" => 20.01, "25" => 2.55 ); 

我试图将绝对值与我的容差值进行比较 - epsilon(比较PHP中的小数)和array_udiff:

function epsilon_compare ($v1,$v2)
{
 $epsilon = 0.02;
 $diff = abs($v1 - $v2);

   if ($diff <= $epsilon) 
    { 
            return 0;
      //echo "numbers are equal";
      } else {
         return 1;
             }
    }

 print_r(array_udiff($post_values, $db_values, "epsilon_compare"));

给出正确的结果:数组([25] => 2.55)

但当我使用不同的数组时,我得到错误的结果,例如:

   $db_values =   array( "21" => 10.00, "22" => 20.00, "25" => …

我有两个关联数组。我需要减去 ($price - $tax) 以获得 $total price：

 $price['lunch'] = array("food" => 10, "beer"=> 6, "wine" => 9);
 $price['dinner'] = array("food" => 15, "beer"=> 10, "wine" => 10);

 $tax['lunch'] = array("food" => 2, "beer"=> 3, "wine" => 2);
 $tax['dinner'] = array("food" => 4, "beer"=> 6, "wine" => 4);

所需的结果数组：

 $result['lunch'] = (['food'] => 8, ['beer'] =>3, ['wine'] => 7 )
 $result['dinner'] = (['food'] => 11, ['beer'] =>4, ['wine'] => 6   )

我正在尝试以下函数和 array_map 无济于事：

function minus($a, $b) {
    return $a - …

我有关联数组(动态 - 可能有更多的数组,但相同的键):

  Array
 (
    [food] => Array
      (
        [0] => 3
        [1] => 4
        [2] => 1
      )

     [liquor] => Array
       (
         [0] => 4
         [1] => 5
         [2] => 0
       )

     [beer] => Array
      (
        [0] => 5
        [1] => 6
        [2] => 0
      )

  )

我需要在每个数组上使用array_sum,结果将是:

Array ( [food] => 8, [liquor] => 9, [beer] => 11 )

谢谢!