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

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

require __dir__ . '/db.php';
$db = new db();
$db->__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

<?php
/**
 * user: salamander
 * date: 2016/9/2
 * time: 9:16
 */

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, $parameters=[], $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, $parameters=[], $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, $parameters=[], $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，谢谢大家对的支持