PHP用PDO如何封装简单易用的DB类详解

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');

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";} 

<?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 { }