变量在函数内未定义，无法到达函数内的 MySQL $connection

Question

当我在页面上使用它时，我有一个代码可以工作，但我试图使它成为一个函数。我无法让它工作，似乎变量 $customer 和 $system 没有被发送到代码。即使我在 Raw 中输入它。知道有什么问题吗？ $Customer 是客户的名字，$system 可以是 'Source' 或者 'Target'.

function status_total($customer, $system){
        $sql_customer       = "SELECT * FROM `Customer` WHERE Cust_Name = '$customer' LIMIT 0,1";
        $customer_selection = mysqli_query($conn,$sql_customer);
        $customer_row       = mysqli_fetch_assoc($customer_selection);
        $env_lines          = $customer_row["Env_Lines"];
        $cust_id            = $customer_row["Cust_ID"];
        $sql_last_records   = "SELECT * FROM $system WHERE Cust_ID = $cust_id ORDER BY Time DESC LIMIT $env_lines";
        $record_selection   = mysqli_query($conn, $sql_last_records);               

        $result = mysqli_fetch_all($record_selection, MYSQLI_ASSOC);
        $states = array_column($result, "Stat");

        if($states == array_fill(0, count($states), "Run")) {
            echo "Success";
        } else 
            echo "Fail";

    }

https://gist.github.com/R2D2-05/78d81566e4bf0eafd1fa

Answer 1

您的代码的问题是 $conn 变量，该变量在函数内被视为局部变量。你应该：

function status_total($customer, $system){
        global $conn;

        $sql_customer       = "SELECT * FROM `Customer` WHERE Cust_Name = '$customer' LIMIT 0,1";
        $customer_selection = mysqli_query($conn,$sql_customer);
        $customer_row       = mysqli_fetch_assoc($customer_selection);
        $env_lines          = $customer_row["Env_Lines"];
        $cust_id            = $customer_row["Cust_ID"];
        $sql_last_records   = "SELECT * FROM $system WHERE Cust_ID = $cust_id ORDER BY Time DESC LIMIT $env_lines";
        $record_selection   = mysqli_query($conn, $sql_last_records);               

        $result = mysqli_fetch_all($record_selection, MYSQLI_ASSOC);
        $states = array_column($result, "Stat");

        if($states == array_fill(0, count($states), "Run")) {
            echo "Success";
        } else 
            echo "Fail";

    }

或者你也可以通过函数传递$conn，所以把函数的定义改成：

function status_total($conn, $customer, $system){...}

变量在函数内未定义，无法到达函数内的 MySQL $connection

Variable is undefined inside a function, cannot reach MySQL $connection inside a function

php

mysql

mysqli

function

fetchall