Question

我是mysqli的新手，正在阅读以下教程：http://www.binpress.com/tutorial/using-php-with-mysql-the-right-way/17#comment1

我能够使用以下方法连接到我的数据库：

$config = parse_ini_file('../config.ini'); 
$connection = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);
if($connection === false) {
die('Connection failed [' . $db->connect_error . ']');
}
echo("hello"); //this worked!

但后来我尝试将它包装在一个函数中（如教程中所讨论的）...我看到你从另一个函数调用连接函数...在教程中，每个函数都从另一个函数调用，另一个函数调用。我从来没有发现最初的呼叫从哪里开始，以获得函数调用海誓山盟的多米诺骨牌效应..所以无论如何，我试图阻止它只是为了测试和教自己......但它没有工作，我不知道为什么：

function db_connect() {
static $connection;

if(!isset($connection)) {
$config = parse_ini_file('../config.ini'); 
$connection = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);
    }
if($connection === false) {
return mysqli_connect_error(); 
}
return $connection;
echo("hello2");
}

function db_query($query) {
$connection = db_connect();
$result = mysqli_query($connection,$query);
return $result;
echo("hello1");

}

db_query("SELECT `Q1_Q`,`Q1_AnsA` FROM `Game1_RollarCoaster`"); //this didn't work :(

Answer 1

好吧，我最终把它从函数中删除并使代码变得非常简单（尽管许多教程都使用OOP，但仍然坚持使用过程而不是OOP - 认为以这种方式开始更好）：

<?php 
$config = parse_ini_file('../config.ini'); 
$link = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);

if(mysqli_connect_errno()){  
echo mysqli_connect_error();  
}  


$query = "SELECT * FROM Game1_RollarCoaster";

$result = mysqli_query($link, $query);

while ($row = mysqli_fetch_array($result)) {

echo $row[Q1_Q] . '<-- Here is your question! ' . $row[Q1_AnsA] . '<-- Here is your answer! ';

echo '<br />';

}

mysqli_free_result($result);
mysqli_close($link);


?>

Answer 2

这是一个简单的mysqli解决方案：

$db = new mysqli('localhost','user','password','database');
$resource = $db->query('SELECT field FROM table WHERE 1');
$row = $resource->fetch_assoc();
echo "{$row['field']}";
$resource->free();
$db->close();

如果您抓取多行，我会这样做：

$db = new mysqli('localhost','user','password','database');
$resource = $db->query('SELECT field FROM table WHERE 1');
while ( $row = $resource->fetch_assoc() ) {
    echo "{$row['field']}";
}
$resource->free();
$db->close();

使用错误处理：如果发生致命错误，脚本将以错误消息终止。

// ini_set('display_errors',1); // Uncomment to show errors to the end user.
if ( $db->connect_errno ) die("Database Connection Failed: ".$db->connect_error);
$db = new mysqli('localhost','user','password','database');
$resource = $db->query('SELECT field FROM table WHERE 1');
if ( !$resource ) die('Database Error: '.$db->error);
while ( $row = $resource->fetch_assoc() ) {
    echo "{$row['field']}";
}
$resource->free();
$db->close();

使用try / catch异常处理：这使您可以在一个地方处理任何错误，并在可能出现故障时继续执行，如果需要的话。

try {
    if ( $db->connect_errno ) throw new Exception("Connection Failed: ".$db->connect_error);
    $db = new mysqli('localhost','user','password','database');
    $resource = $db->query('SELECT field FROM table WHERE 1');
    if ( !$resource ) throw new Exception($db->error);
    while ( $row = $resource->fetch_assoc() ) {
        echo "{$row['field']}";
    }
    $resource->free();
    $db->close();
} catch (Exception $e) {
    echo "DB Exception: ",$e->getMessage(),"\n";
}

mysqli连接和查询

2 个答案: