Question

我得到了：

警告：mysqli_query（）要求参数1为mysqli，在第35行的/Applications/XAMPP/xamppfiles/htdocs/parkgames0.2/private/database.php中给出null

当我运行index.php。

database.php如下：

<?php
require_once("config.php");

class MySQLDatabase {
    private $connection;

    function __constuct() {
        $this->open_connection();
    }

    public function open_connection() {
        // 1. Create a database connection
        $this->connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS);
        if(!$this->connection) {
        die("Database connection failed: " . mysqli_error());
        } else {
            // 2. Select a database to use
            $db_select = mysqli_select_db($this->connection, DB_NAME);
            if(!$db_select) {
                die("Database selection failed: " . mysql_error());
            }
        }

    }

    public function close_connection() {
        // 5. Close connection (if exists)  
        if(isset($this->connection)) {
            mysqli_close($this->connection);
            unset($this->connection);
        }
    }

    public function query($sql) {
        $result = mysqli_query($this->connection, $sql);
        $this->confirm_query($result);
        return $result;
    }

    public function mysql_prep($value) {
        $magic_quotes_active = get_magic_quotes_gpc();
        $new_enough_php = function_exists( "mysql_real_escape_string" ); // i.e. PHP >= v4.3.0
        if( $new_enough_php ) { // PHP v4.3.0 or higher
            // undo any magic quote effects so mysql_real_escape_string can do the work
            if( $magic_quotes_active ) { $value = stripslashes( $value ); }
            $value = mysql_real_escape_string( $value );
        } else { // before PHP v4.3.0
            // if magic quotes aren't already on then add slashes manually
            if( !$magic_quotes_active ) { $value = addslashes( $value ); }
            // if magic quotes are active, then the slashes already exist
        }
        return $value;
    }


    private function confirm_query($result) {
    if(!$result) {
        die("Database query failed");
    }

}
}

$database = new MySQLDatabase();
?>

index.php是：

require_once("../private/database.php");

if(isset($database)) { echo "true"; } else { echo "false";}
echo "<br>";

$query = "SELECT * ";
$query .= "FROM activities ";
$query .= "WHERE id=1";
$query .= " LIMIT 1";
echo $query;
$result = $database->query($query);

$found_activity = mysqli_fetch_array($result);
echo $found_activity["name"];

config.php只包含DB_SERVER，DB_USER，DB_PASS和DB_NAME的定义

Answer 1

mysqli_connect在失败时不返回false。它总是返回一个对象。当它失败时会出错。因此，您必须检查该错误，而不是检查该对象是否存在。

    public function open_connection() {
        // 1. Create a database connection
        $this->connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS);
        if($this->connection->connect_error) {
            die("Database connection failed: " . mysqli_error());
        } else {
            // 2. Select a database to use
            $db_select = mysqli_select_db($this->connection, DB_NAME);
            if(!$db_select) {
                die("Database selection failed: " . mysql_error());
            }
        }
    }

mysqli_query期望参数1为mysqli，null给定

1 个答案: