Php 数据库类,OOP-连接到mysql
这是一个数据库类: DB.phpPhp 数据库类,OOP-连接到mysql,php,mysql,database,pdo,bindparam,Php,Mysql,Database,Pdo,Bindparam,这是一个数据库类: DB.php <?php class DB { public static $instance = null; private $_pdo = null, $_query = null, $_error = false, $_results = null, $_c
<?php
class DB {
public static $instance = null;
private $_pdo = null,
$_query = null,
$_error = false,
$_results = null,
$_count = 0;
private function __construct() {
try {
$this->_pdo = new PDO('mysql:host=' . Config::get('mysql/host') . ';dbname=' . Config::get('mysql/db'), Config::get('mysql/username'), Config::get('mysql/password'));
} catch(PDOExeption $e) {
die($e->getMessage());
}
}
public static function getInstance() {
// Already an instance of this? Return, if not, create.
if(!isset(self::$instance)) {
self::$instance = new DB();
}
return self::$instance;
}
public function query($sql, $params = array()) {
$this->_error = false;
if($this->_query = $this->_pdo->prepare($sql)) {
$x = 1;
if(count($params)) {
foreach($params as $param) {
$this->_query->bindValue($x, $param);
$x++;
}
}
if($this->_query->execute()) {
$this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
$this->_count = $this->_query->rowCount();
} else {
$this->_error = true;
}
}
return $this;
}
public function get($table, $where) {
return $this->action('SELECT *', $table, $where);
}
public function delete($table, $where) {
return $this->action('DELETE', $table, $where);
}
public function action($action, $table, $where = array()) {
if(count($where) === 3) {
$operators = array('=', '>', '<', '>=', '<=');
$field = $where[0];
$operator = $where[1];
$value = $where[2];
if(in_array($operator, $operators)) {
$sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?";
if(!$this->query($sql, array($value))->error()) {
return $this;
}
}
return false;
}
}
public function insert($table, $fields = array()) {
$keys = array_keys($fields);
$values = null;
$x = 1;
foreach($fields as $value) {
$values .= "?";
if($x < count($fields)) {
$values .= ', ';
}
$x++;
}
$sql = "INSERT INTO {$table} (`" . implode('`, `', $keys) . "`) VALUES ({$values})";
if(!$this->query($sql, $fields)->error()) {
return true;
}
return false;
}
public function update($table, $id, $fields = array()) {
$set = null;
$x = 1;
foreach($fields as $name => $value) {
$set .= "{$name} = ?";
if($x < count($fields)) {
$set .= ', ';
}
$x++;
}
$sql = "UPDATE users SET {$set} WHERE id = {$id}";
if(!$this->query($sql, $fields)->error()) {
return true;
}
return false;
}
public function results() {
// Return result object
return $this->_results;
}
public function first() {
return $this->_results[0];
}
public function count() {
// Return count
return $this->_count;
}
public function error() {
return $this->_error;
}
}
当我这样写的时候,分页就起作用了。但我需要一张搜索表。。。那是行不通的
$sql= DB::getInstance()->query(
"SELECT * FROM users
WHERE (category='admin')
LIMIT " . (($page* 5)-5) . ",5");
看看这个类,
query
函数的第二个参数是一个可选的参数数组,因此使用它来传递请求的参数:
$params = array(':request' => 'lolcats');
$limit = $page - 1 * 50;
$query = sprintf(
"SELECT * FROM users
WHERE concat(name, ' ',lastname, ' ', user_id)
LIKE :request
LIMIT %d,50",
$limt
);
$results = DB::getInstance()->query($query, $params);
@保罗很接近,但你还有一个问题: 检查课程的这一部分:
$x = 1;
if(count($params)) {
foreach($params as $param) {
$this->_query->bindValue($x, $param);
$x++;
}
}
它不与命名的占位符绑定,您需要更改代码:
$limit = ($page * 50)-50;
$params = array('%lolcats%', $limit);
$query =
"SELECT * FROM users
WHERE concat(name, ' ',lastname, ' ', user_id)
LIKE ?
LIMIT ?,50";
$results = DB::getInstance()->query($query, $params);
或者将类代码更改为按占位符绑定,如下所示:
#$params = array(':request' =>'%lolcats%', ':limit'=>$limit);
if(count($params)) {
foreach($params as $key=>$value) {
$this->_query->bindValue($key, $value);
}
}
当人们不熟悉OOP时,我在PHP中看到的第一件事就是在构造函数中创建一个PDO对象。将其作为参数注入构造函数,然后将其指定为
$this->pdo
。然后将特定于项目/数据库的逻辑保留在代码库之外,并保存在它所属的配置文件中。我得到以下错误:警告:PDOStatement::execute():SQLSTATE[HY093]:无效参数号:DB.php第52行中未定义参数我认为不能将limit用作绑定参数,因为它将被转义为IIRC,但是参数绑定不正确是一个好地方!
#$params = array(':request' =>'%lolcats%', ':limit'=>$limit);
if(count($params)) {
foreach($params as $key=>$value) {
$this->_query->bindValue($key, $value);
}
}