php - MySQL 和 PHP 数据库？

Question

我正在使用 PHP 和 MySQL 数据库管理进行练习，并且尝试使用 PHP 从表中的字段返回金额。我试图从 food 表中的 CalsPerServ 获取值，其中foodID 等于用户选择的foodID。我现在得到的只是一个数组，而我应该返回一个结果。知道出了什么问题吗？

if($tableName == "meals"){
        $foodsID = filter_input(INPUT_POST, "foodsID");
        $servings = filter_input(INPUT_POST, "Servings");
        $foodsID = mysql_real_escape_string($foodsID);
        $servings = mysql_real_escape_string($servings);

        $query = "SELECT CalsPerServ FROM foods WHERE foodsID=$foodsID";
        $result = mysql_query($query, $connect);
        $CalsPerServ = mysql_fetch_assoc($result);

        print $CalsPerServ;

        $calories = ($CalsPerServ * $servings) * 100;

        $sql .= "(foodsID, Servings, Calories) VALUES ('$foodsID', '$servings', '$calories')";

        $sqltwo = "INSERT INTO daily_diary (foodsID, CaloriesPlus) VALUES ('$foodsID', '$calories')";
        $resulttwo = mysql_query($sqltwo, $connect);
}

Answer 1

问题出在这一行

$calories = ($CalsPerServ * $servings) * 100;

$CalsPerServ 是一个包含查询结果的数组。为了从中获取单列值，您必须像这样使用它

$calories = ($CalsPerServ['CalsPerServ'] * $servings) * 100;