SQL：将单行分成2行或3行

Question

我正在寻找将行分成2行或3行。这可能吗？
我有一个表，显示行情如下：

表名：行情

ID | NAME | BusCost | TaxiCost | TrainCost 
------------------------------------------- 
01 | Steve | NULL | 25  | NULL 
02 | Barry | 15  | 30  | NULL 
03 | Bob | 150  | 400  | 300 

但我想说明这样的行情：

ID | Name | Cost 
------------------ 
01 | Steve | 25 
02 | Barry | 15 
02 | Barry | 30 
03 | Bob | 30 
03 | Bob | 100 
03 | Bob | 70 

我猜我我将需要使用某种UNION来做到这一点，但我很茫然。我对SQL相对比较陌生，并且希望任何人都能指向正确的方向。

我来（不是很紧密要么）最接近的是这样：

SELECT COST 
FROM 
(
SELECT BusCost AS COST FROM Quotes 
UNION 
SELECT TaxiCost AS COST FROM Quotes 
UNION 
SELECT TrainCost AS COST FROM Quotes 
) A 
GROUP BY COST 

SELECT id, name FROM Quotes 
UNION ALL 
SELECT COST 
FROM 
(
SELECT BusCost AS COST FROM Quotes 
UNION 
SELECT TaxiCost AS COST FROM Quotes 
UNION 
SELECT TrainCost AS COST FROM Quotes 
) A 
GROUP BY COST 

任何帮助将不胜感激。

Answer 1

SELECT * 
FROM (
     SELECT id 
     ,  Name 
     ,  BusCost as Cost 
     FROM Quotes 
     UNION ALL 
     SELECT id 
     ,  Name 
     ,  TaxiCost 
     FROM Quotes 
     UNION ALL 
     SELECT id 
     ,  Name 
     ,  TrainCost 
     FROM Quotes 
     ) AllCosts 
WHERE Cost IS NOT NULL 

的where子句删除不具有成本，例如当TaxiCost是空行。使用union all而不是union：后者删除重复的行。