PHP用PDO如何封装简单易用的DB类详解

前言

PDO扩展为PHP访问数据库定义了一个轻量级的、一致性的接口，它提供了一个数据访问抽象层，这样，无论使用什么数据库，都可以通过一致的函数执行查询和获取数据。PDO随PHP5.1发行，在PHP5.0的PECL扩展中也可以使用。

我个人理解：PDO是一个抽象类，为我们提供访问数据的接口方法，下面这篇将给大家介绍关于PHP如何利用PDO封装简单易用的DB类，下面话不多说，来一起看看详细的介绍：

使用

创建测试库和表

rush:sql;"> create database db_test; CREATE TABLE `user` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT,`name` char(11) NOT NULL,`created_at` int(10) unsigned NOT NULL,PRIMARY KEY (`uid`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `user` VALUES ('1','wang','1501109027'); INSERT INTO `user` VALUES ('2','meng','1501109026'); INSERT INTO `user` VALUES ('3','liu','1501009027'); INSERT INTO `user` VALUES ('4','yuan','1500109027');

代码测试

__setup([ 'dsn'=>'MysqL:dbname=db_test;host=localhost','username'=>'root','password'=>'******','charset'=>'utf8' ]);

$user = $db->fetch('SELECT * FROM user where id = :id',['id' => 1]);
echo $user['name'];
echo "\n";

$insertId = $db->insert('user',['name' => 'salamander','created_at' => time()]);
echo "insert user {$insertId}\n";
$users = $db->fetchAll('SELECT * FROM user');
foreach ($users as $item) {
echo "user {$item['id']} is {$item['name']} \n";
}

运行结果

DB工具类

rush:PHP;"> class DB
{
private $dsn;
private $sth;
private $dbh;
private $user;
private $charset;
private $password;

public $lastSQL = '';

public function __setup($config = array())
{
$this->dsn = $config['dsn'];
$this->user = $config['username'];
$this->password = $config['password'];
$this->charset = $config['charset'];
$this->connect();
}

private function connect()
{
if(!$this->dbh){
$options = array(
\PDO::MysqL_ATTR_INIT_COMMAND => 'SET NAMES ' . $this->charset,);
$this->dbh = new \PDO($this->dsn,$this->user,$this->password,$options);
}
}

public function beginTransaction()
{
return $this->dbh->beginTransaction();
}

public function inTransaction()
{
return $this->dbh->inTransaction();
}

public function rollBack()
{
return $this->dbh->rollBack();
}

public function commit()
{
return $this->dbh->commit();
}

function watchException($execute_state)
{
if(!$execute_state){
throw new MysqLException("sql: {$this->lastsql}\n".$this->sth->errorInfo()[2],intval($this->sth->errorCode()));
}
}

public function fetchAll($sql,$parameters=[])
{
$result = [];
$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
while($result[] = $this->sth->fetch(\PDO::FETCH_ASSOC)){ }
array_pop($result);
return $result;
}

public function fetchColumnAll($sql,$parameters=[],$position=0)
{
$result = [];
$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
while($result[] = $this->sth->fetch(\PDO::FETCH_COLUMN,$position)){ }
array_pop($result);
return $result;
}

public function exists($sql,$parameters=[])
{
$this->lastsql = $sql;
$data = $this->fetch($sql,$parameters);
return !empty($data);
}

public function query($sql,$parameters=[])
{
$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
return $this->sth->rowCount();
}

public function fetch($sql,$type=\PDO::FETCH_ASSOC)
{
$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
return $this->sth->fetch($type);
}

public function fetchColumn($sql,$position=0)
{
$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
return $this->sth->fetch(\PDO::FETCH_COLUMN,$position);
}

public function update($table,$condition=[])
{
$table = $this->format_table_name($table);
$sql = "UPDATE $table SET ";
$fields = [];
$pdo_parameters = [];
foreach ( $parameters as $field=>$value){
$fields[] = ''.$field.'=:field_'.$field;
$pdo_parameters['field_'.$field] = $value;
}
$sql .= implode(',',$fields);
$fields = [];
$where = '';
if(is_string($condition)) {
$where = $condition;
} else if(is_array($condition)) {
foreach($condition as $field=>$value){
$parameters[$field] = $value;
$fields[] = ''.$field.'=:condition_'.$field;
$pdo_parameters['condition_'.$field] = $value;
}
$where = implode(' AND ',$fields);
}
if(!empty($where)) {
$sql .= ' WHERE '.$where;
}
return $this->query($sql,$pdo_parameters);
}

public function insert($table,$parameters=[])
{
$table = $this->format_table_name($table);
$sql = "INSERT INTO $table";
$fields = [];
$placeholder = [];
foreach ( $parameters as $field=>$value){
$placeholder[] = ':'.$field;
$fields[] = ''.$field.'';
}
$sql .= '('.implode(",",$fields).') VALUES ('.implode(",$placeholder).')';

$this->lastsql = $sql;
$this->sth = $this->dbh->prepare($sql);
$this->watchException($this->sth->execute($parameters));
$id = $this->dbh->lastInsertId();
if(empty($id)) {
return $this->sth->rowCount();
} else {
return $id;
}
}

public function errorInfo()
{
return $this->sth->errorInfo();
}

protected function format_table_name($table)
{
$parts = explode(".",$table,2);

if(count($parts) > 1) {
$table = $parts[0].".{$parts[1]}";
} else {
$table = "$table";
}
return $table;
}

function errorCode()
{
return $this->sth->errorCode();
}
}

class MysqLException extends \Exception { }

框架中使用建议

在框架中使用DB类,用单例模式或者用依赖容器来管理较好。

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对编程之家的支持