PHP用PDO如何封装简单易用的DB类详解

只看该作者 · 发表于 2018-2-14 05:24:20

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
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，谢谢大家对脚本之家的支持


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