Building a sales query in MS SQL Server

Before we can start visualizing our amazing data in Tableau, we must first put together the query that will provide us that amazing data. We have been asked to put together a sales dashboard that highlights sales from different marketing promotions that have been initiated since the start of AdventureWorks. This promotional data is located in the Sales.SalesReason table in the data warehouse, as seen in the following screenshot:

These results show that there are ten different possible promotions that could have resulted in a sale. The actual sales data is in the Sales.SalesOrderHeader table but that table does not have the SalesReasonID for us to join sales to promotions. The SalesOrderHeader table has a SalesOrderID, as seen in the following script:

SELECT  
distinct [SalesOrderID] 
FROM [AdventureWorks2014].[Sales].[SalesOrderHeader] 

We will need to find a table that can tie SalesOrderID to SalesReasonID. Fortunately, we have a table...