Question

我正在尝试将MySQL表中所有product_id的所有product_price求和。

当我运行$result = "SELECT SUM(product_price) AS product_price FROM products";时，它汇总了所有可以正常工作的product_price。

当我运行$result = "SELECT SUM(product_price) AS product_price FROM products WHERE product_id = $school_product_id";时，它给我一个数组错误。

我希望查询从explode / foreach获取所有4个ID，并显示总价。

正在爆炸的数据库字段看起来像“ 1,2,3,4”，与下面的product_id表中的products匹配。

    $row = $result->fetch_assoc();
    $school_subject_products = $row["school_subject_products"];  // (output is 1,2,3,4)
    $school_product_id = explode(',', $school_subject_products); // (explode 1,2,3,4 to use in query below to calculate all 4 product_id's product_price)


    $result = "SELECT SUM(product_price) AS product_price FROM products WHERE product_id = ??????????"; //<------ how do I get it to search for all 4 product_ids and total the price of all the product_ids
    $price_result = $mysqli->query($result);
    $row = $price_result->fetch_assoc();
    $sum = $row['product_price'];
    echo $sum;

    ?>

Answer 1

理想的解决方案是对数据进行规范化处理，这样就没有逗号分隔的列表。

如果无法执行此操作，则可以将JOIN与FIND_IN_SET()配合使用，以与逗号分隔的列表进行匹配，而不必执行多个查询并使用explode()。

SELECT SUM(product_price) AS product_price
FROM products AS p
JOIN select_subject AS s ON FIND_IN_SET(p.product_id, s.school_subject_products)
WHERE school_id = $selected_school_id AND school_year_id = $selected_year_id AND  school_subject_id = $school_subject_selected

PHP从爆炸/ foreach循环获取ID并计算价格

1 个答案: