Sql server 2008 将2个查询合并为1个结果

我有以下两个问题：

SELECT brt.RequestTypeID, brt.RequestTypeName, brs.RequestStepName AS PreviousStep 
FROM b_Steps bs
INNER JOIN b_RequestStep brs ON bs.RequestStepID = brs.RequestStepID 
INNER JOIN b_RequestType brt ON bs.RequestTypeID = brt.RequestTypeID

第二个：

SELECT brt.RequestTypeID, brt.RequestTypeName, brs.RequestStepName AS NextStep 
FROM b_Steps bs 
INNER JOIN b_RequestStep brs ON bs.NextStepID = brs.RequestStepID 
INNER JOIN b_RequestType brt ON bs.RequestTypeID = brt.RequestTypeID

如何组合2个查询并返回如下结果：

| RequestTypeName | PreviousStep | NextStep      |
|------------------------------------------------|
| Buy good        | Login        | Add into cart |

试试这个

select a.RequestTypeName, a.PreviousStep, b.NextStep
from
(SELECT brt.RequestTypeID, brt.RequestTypeName, brs.RequestStepName AS PreviousStep 
FROM b_Steps bs 
INNER JOIN b_RequestStep brs ON bs.RequestStepID = brs.RequestStepID 
INNER JOIN b_RequestType brt ON bs.RequestTypeID = brt.RequestTypeID) as a
inner join 
(SELECT brt.RequestTypeID, brt.RequestTypeName, brs.RequestStepName AS NextStep 
FROM b_Steps bs 
INNER JOIN b_RequestStep brs ON bs.NextStepID = brs.RequestStepID 
INNER JOIN b_RequestType brt ON bs.RequestTypeID = brt.RequestTypeID) as b
on a.RequestTypeID = b.RequestTypeID

---

这很简单，但也许我错过了一些东西：

SELECT brt.RequestTypeID, brt.RequestTypeName
,      brsp.RequestStepName AS PreviousStep 
,      brsn.RequestStepName AS NextStep 
FROM b_Steps bs
INNER JOIN b_RequestType brt ON bs.RequestTypeID = brt.RequestTypeID
LEFT JOIN b_RequestStep brsp ON bs.RequestStepID = brsp.RequestStepID 
LEFT JOIN b_RequestStep brsn ON bs.NextStepID = brsn.RequestStepID 

---

我不知道您是否有没有上一个或下一个步骤，我在这两种情况下都使用了左连接

hj PK20，是复制品你想要复制品吗？阅读有关UNION和UNION ALL的更多信息

步骤中的主键是什么

？表b_步骤：RequestTypeID | RequestStepID | NextStepID（PK）正是我需要的。非常感谢你ツ