SELECT COUNT(*) INTO @cnt FROM information_schema.columns
WHERE table_schema = DATABASE() AND table_name = 'transport_type' AND column_name = 'measure_distance';

SET @q = IF(@cnt <= 0, 
"ALTER TABLE transport_type ADD COLUMN measure_distance TINYINT(1) NULL DEFAULT NULL COMMENT 'Měřit vzdálenost' AFTER delivery_holiday",
'select \'Column exists\' status');

 PREPARE stmt from @q;
 EXECUTE stmt;
 DEALLOCATE PREPARE stmt;