致命错误：在第 9 行的 null 上调用成员函数 fetch_assoc()

Question

不明白

<?php

$mysqli = new mysqli ('localhost', 'root', '', 'UTS');
$mysqli->query("SET NAMES 'utf-8'");
$result_set = $mysqli->query ("SELECT * FROM 'product'");
$mysqli -> close();

function printResult ($result_set) {
    while (($row = $result_set->fetch_assoc()) != false) {
        print_r ($row);
        echo "<br/>";
    }
}

Answer 1

你可以这样尝试......你必须获取那个数组然后你可以打印....

<?php
$mysqli = new mysqli ('localhost', 'root', '', 'db_name');
$mysqli->query("SET NAMES 'utf-8'");
$result_set= mysqli_query($mysqli,"SELECT * FROM products");
$row=mysqli_num_rows($result_set);
echo $row;
while($row=mysqli_fetch_array($result_set))
{            
print_r($row);
}
?>

Answer 2

1. $result_set

   在功能范围之外。您无法在函数内访问它。
2. 你选择的是字符串而不是表名

尝试以下更改：

<?php



function printResult () {
    $mysqli = new mysqli ('localhost', 'root', '', 'UTS');
    $mysqli->set_charset("utf-8"); //Better to do it this way
    $result_set = $mysqli->query ("SELECT * FROM `product`"); //Not the ` instead of '

    while (($row = $result_set->fetch_assoc()) != false) {
        print_r ($row);
        echo "<br/>";
    }
    $mysqli -> close();
}

你可以从任何地方运行这个功能。