Database Exception – yii\db\Exception

                $this->pdoStatement->closeCursor();
            }
 
            Yii::endProfile($token, 'yii\db\Command::query');
        } catch (\Exception $e) {
            Yii::endProfile($token, 'yii\db\Command::query');
            throw $this->db->getSchema()->convertException($e, $rawSql);
        }
 
        if (isset($cache, $cacheKey, $info)) {
            $cache->set($cacheKey, [$result], $info[1], $info[2]);
            Yii::trace('Saved query result in cache', 'yii\db\Command::query');
        }

     * @return array|boolean the first row (in terms of an array) of the query result. False is returned if the query
     * results in nothing.
     * @throws Exception execution failed
     */
    public function queryOne($fetchMode = null)
    {
        return $this->queryInternal('fetch', $fetchMode);
    }
 
    /**
     * Executes the SQL statement and returns the value of the first column in the first row of data.
     * This method is best used when only a single value is needed for a query.
     * @return string|null|boolean the value of the first column in the first row of the query result.

     * If this parameter is not given, the `db` application component will be used.
     * @return array|boolean the first row (in terms of an array) of the query result. False is returned if the query
     * results in nothing.
     */
    public function one($db = null)
    {
        return $this->createCommand($db)->queryOne();
    }
 
    /**
     * Returns the query result as a scalar value.
     * The value returned will be the first column in the first row of the query results.
     * @param Connection $db the database connection used to generate the SQL statement.

     * @return ActiveRecord|array|null a single row of query result. Depending on the setting of [[asArray]],
     * the query result may be either an array or an ActiveRecord object. Null will be returned
     * if the query results in nothing.
     */
    public function one($db = null)
    {
        $row = parent::one($db);
        if ($row !== false) {
            $models = $this->populate([$row]);
            return reset($models) ?: null;
        } else {
            return null;
        }

            if (!isset($component)) {
                $component = Yii::createObject($class);
            }
 
            if ($component instanceof BootstrapInterface) {
                Yii::trace("Bootstrap with " . get_class($component) . '::bootstrap()', __METHOD__);
                $component->bootstrap($this);
            } else {
                Yii::trace("Bootstrap with " . get_class($component), __METHOD__);
            }
        }
    }
 

    protected function bootstrap()
    {
        $request = $this->getRequest();
        Yii::setAlias('@webroot', dirname($request->getScriptFile()));
        Yii::setAlias('@web', $request->getBaseUrl());
 
        parent::bootstrap();
    }
 
    /**
     * Handles the specified request.
     * @param Request $request the request to be handled
     * @return Response the resulting response

    /**
     * @inheritdoc
     */
    public function init()
    {
        $this->state = self::STATE_INIT;
        $this->bootstrap();
    }
 
    /**
     * Initializes extensions and executes bootstrap components.
     * This method is called by [[init()]] after the application has been fully configured.
     * If you override this method, make sure you also call the parent implementation.

     */
    public function __construct($config = [])
    {
        if (!empty($config)) {
            Yii::configure($this, $config);
        }
        $this->init();
    }
 
    /**
     * Initializes the object.
     * This method is invoked at the end of the constructor after the object is initialized with the
     * given configuration.

        $this->state = self::STATE_BEGIN;
 
        $this->preInit($config);
 
        $this->registerErrorHandler($config);
 
        Component::__construct($config);
    }
 
    /**
     * Pre-initializes the application.
     * This method is called at the beginning of the application constructor.
     * It initializes several important application properties.