php - MySqLi 由于某种原因无法工作

Question

实际上，我正在尝试使用 MySqli，但它对我不起作用，即使它显示数据库已连接，但查询也不起作用，即使没有给出任何错误。我尝试使用下面的代码:

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);


    $connect = mysqli_connect("localhost",'dbu', 'password');
    if($connect){
    echo 'connected';   
    }
    else {
    echo 'Failed:'.mysqli_error();  
    }
    mysqli_select_db('dbname',$connect);

    if($query = mysqli_query("SELECT * FROM `users`")){
    $num = mysqli_num_rows($query);
    while($fetch = mysqli_fetch_array($query)){
    echo $id = $fetch['id'];
    }
    }
    else {
    echo 'error:'.mysqli_error();   
    }

Answer 1

打开错误，mysqli_* 函数中有错误。将您的代码更改为

$connect = mysqli_connect("localhost", 'dbu', 'password');
if ($connect) {
    echo 'connected';
} else {
    echo 'Failed:'.mysqli_connect_error();
}
mysqli_select_db($connect, 'dbname'); // <-------change this

if ($query = mysqli_query($connect, "SELECT * FROM `users`")) { //<---------------change this
    $num = mysqli_num_rows($query);
    while ($fetch = mysqli_fetch_array($query)) {
        echo $id = $fetch['id'];
    }
} else {
    echo 'error:'.mysqli_error($connect);
}