我想创建一个包含各种通用变量和函数的类，以便在整个网站中使用。其中之一将是数据库连接。我正在尝试以下代码：
class Sys {
public $dbc = new mysqli('localhost', 'user', 'pass', 'db');
$dbc->query("SET NAMES 'utf8' COLLATE 'utf8_unicode_ci'");
}
$system = new Sys;
它在课堂的第一行给了我一个语法错误......我做错了什么？ 谢谢
【问题讨论】：
标签： php database class connect
你应该在构造函数中做这样的事情。您只能在初始声明中设置原语。创建对象时还需要大括号。
class Sys {
private $dbc;
private $someInteger = 4; // you can do this
private $someArray = array(); // and this.
public function __construct()
{
$this->dbc = new mysqli('localhost', 'user', 'pass', 'db');
$this->dbc->query("SET NAMES 'utf8' COLLATE 'utf8_unicode_ci'");
}
public function getDbc()
{
return $this->dbc;
}
}
$system = new Sys();
//$system->getDbc()->soSomethingWithMyDb();
我建议你阅读使用对象：http://php.net/manual/en/language.types.object.php
【讨论】：
您应该只声明一个公共 $dbc。
然后有一个构造函数function __construct() { ...... } 在那里你初始化它/设置它。
class Sys {
public $dbc;
function __construct() {
$this->dbc = new mysqli('localhost', 'user', 'pass', 'db');
$this->dbc->query("SET NAMES 'utf8' COLLATE 'utf8_unicode_ci'");
}
}
$system = new Sys;
【讨论】：
class Sys {
var $mysqli;
function DB($database,$server,$user,$pass) {
$this->mysqli = mysqli_connect($server, $user, $pass, $base) or die('Server connection not possible. '. mysqli_connect_error());
}
}
include("db.class.mysqli.php"); // db handler class
// Open the base (construct the object):
$db = new Sys(DB_NAME, SERVER_NAME, USER_NAME, PASSWORD);
我就是这样做的
【讨论】：
查看 php 中魔术方法 http://php.net/manual/en/language.oop5.magic.php 的使用 - 如上所述，您的类需要 __construct 方法才能工作。下面是 Peter Lavin 的书 Object Oriented PHP http://objectorientedphp.com/ 第 9 章中的示例。
class MySQLConnect {
// Data Members
private $connection;
private static $instances = 0;
// Constructor
public function __construct($hostname, $username, $password) {
if(MySQLConnect::$instances == 0) {
$this->connection = new mysqli($hostname, $username, $password);
// Check for Errors then report them
if ($this->connection->connect_error) {
die("Connect Error ($this->connection->connect_errno) $this->connection->connect_error");
}
// Set the Class variable $instances to 1
MySQLConnect::$instances = 1;
} else {
$msg = "There's another instance the MySQLConnect Class with a connect open already. Close it";
die($msg);
}
}
}
【讨论】：
试试这个：
$db = new DB;
$link = $db->connect()->getLink();
class DB {
public $connection = array();
public function __construct() {
return $this;
}
public function connect($host=null, $user=null, $pass=null, $database=null) {
$this->connection = new Connection($host, $user, $pass, $database);
$this->connection->connect();
$this->link = $this->connection->getLink();
if ($this->connection->ping()) {
if (!is_null($database)) {
if (!$this->connection->databaseConnect($database)) {
throw new\Exception('Unable to connect to the server.');
}
}
}else{
throw new \Exception('Unable to connect to the server.');
}
return $this;
}
public function getLink() {
return $this->link;
}
}
class Connection {
protected $chost='localhost';
protected $cuser='guest';
protected $cpass='password';
protected $cdatabase='PROFORDABLE';
function __construct($host=null, $user=null, $pass=null, $database=null) {
$host = !is_null($host) ? $host : $this->chost;
$user = !is_null($user) ? $user : $this->cuser;
$password = !is_null($pass) ? $pass : $this->cpass;
$database = !is_null($database) ? $database : $this->cdatabase;
$this->set('host', $host)->set('user', $user)->set('password', $password)->set('database', $database);
return $this;
}
public function connect() {
$link = mysqli_connect($this->host->getHost(), $this->user->getUser(), $this->password->getPassword());
if (!is_object($link)) {
throw new \Exception("An error has occurred while connecting to the server.");
}
$this->link = $link;
}
public function databaseConnect($database) {
if (!mysqli_select_db($this->getLink(), $database)) {
throw new \Exception("Unable to select the database.");
}
}
public function getLink() {
return $this->link;
}
public function ping() {
if (mysqli_ping($this->link)) {
return TRUE;
}
return FALSE;
}
public function set($name, $param) {
if (!isset($name) || !isset($param)) return $this;
$class = __NAMESPACE__.'\\'.ucwords($name);
$this->$name = new $class($param);
return $this;
}
public function get($name) {
$getfunc = 'get'.ucwords($name);
return $this->$name->$getFunc();
}
}
class Host {
public function __construct($host) {
$this->setHost($host);
}
public function setHost($host) {
$this->host = $host;
}
public function getHost() {
return $this->host;
}
}
class User {
public function __construct($user) {
$this->setUser($user);
}
public function setUser($user) {
$this->user = $user;
}
public function getUser() {
return $this->user;
}
}
class Password {
public function __construct($password) {
$this->setPassword($password);
}
public function setPassword($password) {
$this->password = $password;
}
public function getPassword() {
return $this->password;
}
public function sha($value) {
return sha1($value);
}
}
class guestPassword extends Password {
const PASSWORD='password';
public function __construct() {
return PASSWORD;
}
}
class Database {
public function __construct($database) {
$this->setDatabase($database);
}
public function setDatabase($database) {
$this->database = $database;
}
public function getDatabase() {
return $this->database;
}
}
class Query {
}
【讨论】：
//Create mysql.php and paste following code
<?php
class MySQL {
private $set_host;
private $set_username;
private $set_password;
private $set_database;
public function __Construct($set_host, $set_username, $set_password) {
$this->host = $set_host;
$this->username = $set_username;
$this->password = $set_password;
$con = mysql_connect($this->host, $this->username, $this->password);
if (!$con) {
die("Couldn't connect to the server");
}
}
//end of __construct
//connect to database
public function Database($set_database) {
$this->database = $set_database;
mysql_query("set character_set_server='utf8'");
mysql_query("set names 'utf8'");
mysql_select_db($this->database) or die("Unable to select database");
}
//fetch data from any table
public function fetch_data($sql) {
$this->sql = $sql;
$query = mysql_query($this->sql);
$result = array();
while ($record = mysql_fetch_array($query)) {
$result[] = $record;
}
return $result;
}
//fetch all columns from any table to be used for INSERT INTO.
public function get_all_columns($table_name) {
$this->table_name = $table_name;
$sql = "SHOW COLUMNS FROM $this->table_name";
$result = mysql_query($sql);
while ($record = mysql_fetch_array($result)) {
$fields[] = $record['0'];
}
$val = '';
foreach ($fields as $value) {
$val .= $value . ',';
}
$vals = rtrim($val, ',');
return $vals;
}
//insert data to any table by $_POST or set of variables separated by ,
public function insert_data($tbl_name, $tbl_value) {
$this->tbl_name = $tbl_name;
$this->tbl_value = $tbl_value;
//use mysql_real_escape_string($tbl_value) to clean & insert data.
$this->tbl_col = $this->get_all_columns($this->tbl_name);
$sql = "INSERT INTO $this->tbl_name ($this->tbl_col) VALUES ($this->tbl_value)";
$query_result = mysql_query($sql);
}
//end of insert data
public function delete_data($del_id, $table_name) {
$this->del_id = $del_id;
$this->table_name = $table_name;
if (isset($this->del_id) && is_numeric($this->del_id) && !empty($this->del_id)) {
$sql = "DELETE FROM $this->table_name WHERE id=$this->del_id LIMIT 1";
$del_result = mysql_query($sql);
$aff_row = mysql_affected_rows();
return $aff_row;
}
}
}
// class ends here
//call class to connect to server and db as well.
$connect = new MySQL('localhost', 'root', '');
$connect->Database('db_name');
?>
//include file mysql.php and call your class object as :
//fetching data from any table use :
$variable = $connect->fetch_data("SELECT * FROM table_name");
for($i=0;$i<count($variable);$i++){
$result = $variable[$i]['col_name'];
}
//insert INTO values in any table
$result = $connect->insert_data($tbl_name, $tbl_value);
if($result)
echo 'inserted';
else{
echo 'failed';
}
//delete record from any table
$result = $connect->delete_data($del_id, $table_name)
【讨论】：
你可以用精彩的课ezSQL
【讨论】：