Question

我有2个表，我需要总结每个表价格列的总价值。我对Stack进行了一些研究，但我看到的解决方案太长了，而且代码看起来效率不高。使用MySQL我试图从StoreCoins获得总价值加上StoreMemorabilia的总价值和供应品的总价值然后我想要两个表格列总和的总和。第一个代码目前无效...

if($results = $this->dbConn->query("SELECT SUM(column) AS InventoryValue FROM (
                                        SELECT SUM(column) AS value FROM StoreCoins
                                        UNION ALL
                                        SELECT SUM(column) AS value FROM StoreMemorabilia
                                        ) allposts")){
while($data = $results->fetch_assoc()){
    $totalVal = $data['InventoryValue'];
    $totalVal .= ".00";

我需要知道上面的代码中我做错了什么。

另一个注意事项（这与php有关）：我有以下脚本，一旦返回正确的值，它决定将逗号放在美元值的位置。我想建议一个更有效的方法来创建这个功能及其结果。 switch语句工作得很好，做了我需要做的事情，我只想要一种更有说服力的写作方式。

switch(strlen($Val)){
    case 7:
        $rem = substr($Val, 1, 6);
        $Val = substr_replace($Val, ",", 1);
        $Val = $Val.$rem;
        break;
    case 8:
        $rem = substr($Val, 2, 6);
        $Val = substr_replace($Val, ",", 2);
        $Val = $Val.$rem;
        break;
    case 9:
        $rem = substr($Val, 3, 6);
        $Val = substr_replace($Val, ",", 3);
        $Val = $totalVal.$rem;
        break;
    case 10:
        $rem = substr($Val, 1, 10);
        $Val = substr_replace($Val, ",", 1);
        $Val = $Val.$rem;
        $rema = substr($Val, 5, 6);
        $Val = substr_replace($Val, ",", 5);
        $Val = $Val.$rema;
}

Answer 1

我希望以下是您的目标：

select (
    ( select sum(`price`) from `StoreCoins` ) 
        + 
    ( select sum(`price`) from `StoreMemorabilia` )
) as 'total';

Answer 2

像这样更改查询

SELECT SUM(column) FROM ( 
SELECT SUM(column) AS value FROM StoreCoins

UNION 

SELECT SUM(column) AS value FROM StoreMemorabilia
) InventoryValue

使用php从MySQL中的多个表中添加总值

2 个答案: