mysqli connection and query

问题:

I am new to mysqli and was going through a tutorial from: http://www.binpress.com/tutorial/using-php-with-mysql-the-right-way/17#comment1

I was able to connect to my database using this:

$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!

But then I tried wrapping it in a function (as discussed in the tutorial)... I saw that you call the connection function from another function... in the tutorial each function keeps getting called from another and another... and I never quite found where the initial call started from to get the domino effect of functions calling eachother.. so anyway, I tried to stop it at two just to test and teach myself.. but it's not working and I don't know why:

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 :(

回答1:

Well I ended up taking it out of the functions and made the code super simple (sticking with procedural instead of OOP even though a lot of tutorials use OOP - thought it was better to start this way):

<?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);


?> 

回答2:

Here's a simple mysqli solution for you:

$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();

If you're grabbing more than one row, I do it like this:

$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();

With Error Handling: If there is a fatal error the script will terminate with an error message.

// 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();

With try/catch exception handling: This lets you deal with any errors all in one place and possibly continue execution when something fails, if that's desired.

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";
}