本文实例讲述了php实现的pdo公共类定义与用法。分享给大家供大家参考，具体如下：
db.class.php ：
<?php
class db extends pdo {
private static $_instance = null;
protected $dbname = '';
protected $dsn;
protected $dbh;
public function __construct($dbhost, $dbuser, $dbpasswd, $dbname, $dbcharset='utf8') {
try {
$this->dsn = 'mysql:host=' . $dbhost . ';dbname=' . $dbname;
$this->dbh = new pdo($this->dsn, $dbuser, $dbpasswd);
$this->dbh->setattribute(pdo::attr_emulate_prepares, false);
$this->dbh->setattribute(pdo::attr_errmode, pdo::errmode_exception);
$this->dbh->exec('set character_set_connection='.$dbcharset.';set character_set_client='.$dbcharset.';set character_set_results='.$dbcharset);
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public static function getinstance($dbhost, $dbuser, $dbpasswd, $dbname, $dbcharset='utf8') {
if (self::$_instance === null) {
self::$_instance = new self($dbhost, $dbuser, $dbpasswd, $dbname, $dbcharset);
}
return self::$_instance;
}
public function fetchall($sql, $params = array()) {
try {
$stm = $this->dbh->prepare($sql);
if ($stm && $stm->execute($params)) {
return $stm->fetchall(pdo::fetch_assoc);
}
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function fetchone($sql, $params = array()) {
try {
$result = false;
$stm = $this->dbh->prepare($sql);
if ($stm && $stm->execute($params)) {
$result = $stm->fetch(pdo::fetch_assoc);
}
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function fetchcolumn($sql, $params = array()) {
$result = '';
try {
$stm = $this->dbh->prepare($sql);
if ($stm && $stm->execute($params)) {
$result = $stm->fetchcolumn();
}
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function insert($table, $params = array(), $returnlastid = true) {
$_implode_field = '';
$fields = array_keys($params);
$_implode_field = implode(',', $fields);
$_implode_value = '';
foreach ($fields as $value) {
$_implode_value .= ':'. $value.',';
}
$_implode_value = trim($_implode_value, ',');
$sql = 'insert into ' . $table . '(' . $_implode_field . ') values ('.$_implode_value.')';
try {
$stm = $this->dbh->prepare($sql);
$result = $stm->execute($params);
if ( $returnlastid ) {
$result = $this->dbh->lastinsertid();
}
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function update($table, $params = array(), $where = null) {
$_implode_field = '';
$_implode_field_arr = array();
if ( empty($where) ) {
return false;
}
$fields = array_keys($params);
foreach ($fields as $key) {
$_implode_field_arr[] = $key . '=' . ':'.$key;
}
$_implode_field = implode(',', $_implode_field_arr);
$sql = 'update ' . $table . ' set ' . $_implode_field . ' where ' . $where;
try {
$stm = $this->dbh->prepare($sql);
$result = $stm->execute($params);
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function delete($sql, $params = array()) {
try {
$stm = $this->dbh->prepare($sql);
$result = $stm->execute($params);
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
public function exec($sql, $params = array()) {
try {
$stm = $this->dbh->prepare($sql);
$result = $stm->execute($params);
return $result;
} catch (exception $e) {
$this->outputerror($e->getmessage());
}
}
private function outputerror($strerrmsg) {
throw new exception("mysql error: " . $strerrmsg);
}
public function __destruct() {
$this->dbh = null;
}
}
实例：
<?php
require_once './db.class.php';
$pdo = db::getinstance('127.0.0.1', 'root', '111111', 'php_cms');
$sql = "select id, title1 from cms_wz where id = :id limit 1";
$parame = array('id' => 12,);
$res = $pdo->fetchone($sql, $parame);
var_dump($res);
$sql = 'select * from cms_link';
$result = $db->fetchall($sql);
print_r($result);
//查询记录数量
$sql = 'select count(*) from cms_link';
$count = $db->fetchcolumn($sql);
echo $count;
$data = array(
'siteid' => 1,
'linktype' => 1,
'name' => 'google',
'url' => 'http://www.google.com',
'listorder' => 0,
'elite' => 0,
'passed' => 1,
'addtime' => time()
);
$lastinsertid = $db->insert('cms_link', $data);
echo $lastinsertid;
//用 try
try {
$result = $pdo->insert('news', $essay);
} catch (exception $e) {
error_log($e->getmessage());
error_log($e->getmessage() . ' in ' . __file__ . ' on line ' . __line__);
savelog('url文章 : ' . $essay['link'] . ' 数据插入失败<br>');
continue;
}
$data = array(
'siteid' => 1,
'linktype' => 1,
'name' => 'google',
'url' => 'http://www.google.com',
'listorder' => 0,
'elite' => 0,
'passed' => 1,
'addtime' => time()
);
$db->insert('cms_link', $data);
$sql = 'delete from cms_link where linkid=4';
$result = $db->delete($sql);
var_dump($result);
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