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 "
";

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

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: {$this->lastSQL}
".$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，谢谢大家对网页设计的支持