mysqli连接和查询 - mysqli connection and query

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

我可以用这个连接到我的数据库：

$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!

但后来我尝试将它封装在一个函数中（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，每个函数都不断地被另一个和另一个调用。。。我从来没有完全找到最初的调用是从哪里开始的，以获得函数相互调用的多米诺骨牌效应。。所以不管怎样，我试着在两点停止，只是为了测试和自学。。但它不起作用，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 :(

我最终将其从函数中删除，并使代码变得超级简单（尽管许多教程都使用OOP，但仍坚持过程化而非OOP-认为这样开始更好）：

<?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);

?>

这里有一个简单的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();

如果你抓了不止一排，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：如果出现致命错误，脚本将终止并显示错误消息。

// 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：这可以让您在一个地方处理所有错误，如果需要，还可以在出现故障时继续执行。

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";
}