public function findForeignKeys ($table, $column = null)
		{
			$query = ( new  Query )
				->select('CONSTRAINT_NAME')
				->from('INFORMATION_SCHEMA.KEY_COLUMN_USAGE')
				->where([
					'TABLE_SCHEMA' => $this->getDbName(),
					'TABLE_NAME'   => $table
				]);
			if (!is_null($column))
				$query->andWhere([ 'COLUMN_NAME' => $column ]);

			return $query->column();
		}