PHP使用PDO封装一个简单易用的DB类

摘要：使用创建测试库和表代码测试运行结果工具类安装框架中使用建议在框架中使用类用单例模式或者用依赖容器来管理较好。

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 "
";

$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

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 { }

SimpleDB

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。