gistfile1.php

    /**
     * begin transaction
     */
    public function begin()
    {
        if(count($this->transactionStack) == 0)
        {
            $this->transactionStack[0] = true;
            parent::beginTransaction();
        }
        else
        {
            $savePoint = 'savepoint_'. count($this->transactionStack);
            array_push($this->transactionStack, $savePoint);

            $this->setSavePoint($savePoint);
        }
    }

    /**
     * commit
     */
    public function commit()
    {
        if(count($this->transactionStack) > 1)
        {
            $savePoint = array_pop($this->transactionStack);
            $this->releaseSavePoint($savePoint);
        }
        else
        {
            $this->transactionStack = array();
            parent::commit();
        }
    }

    /**
     * rollback
     */
    public function rollback()
    {
        /**
         * Take care of nesting transaction blocks
         */
        if(count($this->transactionStack) > 1)
        {
            $savePoint = array_pop($this->transactionStack);
            $this->rollbackToSavePoint($savePoint);
        }
        else
        {
            $this->transactionStack = array();
            parent::rollback();
        }
    }